diff --git a/.github/workflows/pull-compliance.yml b/.github/workflows/pull-compliance.yml
index fb81622bd6945..12e84ff6f993d 100644
--- a/.github/workflows/pull-compliance.yml
+++ b/.github/workflows/pull-compliance.yml
@@ -214,6 +214,16 @@ jobs:
           GOOS: linux
           GOARCH: 386
 
+  i18n-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          check-latest: true
+      - run: make i18n-check
+
   docs:
     if: needs.files-changed.outputs.docs == 'true' || needs.files-changed.outputs.actions == 'true'
     needs: files-changed
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 52e4aefb6b729..c64d91a7ebbed 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -183,7 +183,7 @@ Here's how to run the test suite:
 ## Translation
 
 All translation work happens on [Crowdin](https://translate.gitea.com).
-The only translation that is maintained in this repository is [the English translation](https://github.com/go-gitea/gitea/blob/main/options/locale/locale_en-US.ini).
+The only translation that is maintained in this repository is [the English translation](https://github.com/go-gitea/gitea/blob/main/options/locale/locale_en-US.json).
 It is synced regularly with Crowdin. \
 Other locales on main branch **should not** be updated manually as they will be overwritten with each sync. \
 Once a language has reached a **satisfactory percentage** of translated keys (~25%), it will be synced back into this repo and included in the next released version.
diff --git a/Makefile b/Makefile
index 605461158077c..299eb1c164f97 100644
--- a/Makefile
+++ b/Makefile
@@ -887,6 +887,16 @@ lockfile-check:
 		exit 1; \
 	fi
 
+.PHONY: i18n-backport
+i18n-backport:
+	@echo "Backport translations ..."
+	$(GO) run tools/i18n/backport.go
+
+.PHONY: i18n-check
+i18n-check:
+	@echo "Checking unused translations..."
+	$(GO) run tools/i18n/check.go
+
 .PHONY: generate-gitignore
 generate-gitignore: ## update gitignore files
 	$(GO) run build/generate-gitignores.go
diff --git a/build/backport-locales.go b/build/backport-locales.go
deleted file mode 100644
index d112dd72bd56e..0000000000000
--- a/build/backport-locales.go
+++ /dev/null
@@ -1,115 +0,0 @@
-// Copyright 2023 The Gitea Authors. All rights reserved.
-// SPDX-License-Identifier: MIT
-
-//go:build ignore
-
-package main
-
-import (
-	"fmt"
-	"os"
-	"os/exec"
-	"path/filepath"
-	"strings"
-
-	"code.gitea.io/gitea/modules/container"
-	"code.gitea.io/gitea/modules/setting"
-)
-
-func main() {
-	if len(os.Args) != 2 {
-		println("usage: backport-locales <to-ref>")
-		println("eg: backport-locales release/v1.19")
-		os.Exit(1)
-	}
-
-	mustNoErr := func(err error) {
-		if err != nil {
-			panic(err)
-		}
-	}
-	collectInis := func(ref string) map[string]setting.ConfigProvider {
-		inis := map[string]setting.ConfigProvider{}
-		err := filepath.WalkDir("options/locale", func(path string, d os.DirEntry, err error) error {
-			if err != nil {
-				return err
-			}
-			if d.IsDir() || !strings.HasSuffix(d.Name(), ".ini") {
-				return nil
-			}
-			cfg, err := setting.NewConfigProviderForLocale(path)
-			mustNoErr(err)
-			inis[path] = cfg
-			fmt.Printf("collecting: %s @ %s\n", path, ref)
-			return nil
-		})
-		mustNoErr(err)
-		return inis
-	}
-
-	// collect new locales from current working directory
-	inisNew := collectInis("HEAD")
-
-	// switch to the target ref, and collect the old locales
-	cmd := exec.Command("git", "checkout", os.Args[1])
-	cmd.Stdout = os.Stdout
-	cmd.Stderr = os.Stderr
-	mustNoErr(cmd.Run())
-	inisOld := collectInis(os.Args[1])
-
-	// use old en-US as the base, and copy the new translations to the old locales
-	enUsOld := inisOld["options/locale/locale_en-US.ini"]
-	brokenWarned := make(container.Set[string])
-	for path, iniOld := range inisOld {
-		if iniOld == enUsOld {
-			continue
-		}
-		iniNew := inisNew[path]
-		if iniNew == nil {
-			continue
-		}
-		for _, secEnUS := range enUsOld.Sections() {
-			secOld := iniOld.Section(secEnUS.Name())
-			secNew := iniNew.Section(secEnUS.Name())
-			for _, keyEnUs := range secEnUS.Keys() {
-				if secNew.HasKey(keyEnUs.Name()) {
-					oldStr := secOld.Key(keyEnUs.Name()).String()
-					newStr := secNew.Key(keyEnUs.Name()).String()
-					broken := oldStr != "" && strings.Count(oldStr, "%") != strings.Count(newStr, "%")
-					broken = broken || strings.Contains(oldStr, "\n") || strings.Contains(oldStr, "\n")
-					if broken {
-						brokenWarned.Add(secOld.Name() + "." + keyEnUs.Name())
-						fmt.Println("----")
-						fmt.Printf("WARNING: skip broken locale: %s , [%s] %s\n", path, secEnUS.Name(), keyEnUs.Name())
-						fmt.Printf("\told: %s\n", strings.ReplaceAll(oldStr, "\n", "\\n"))
-						fmt.Printf("\tnew: %s\n", strings.ReplaceAll(newStr, "\n", "\\n"))
-						continue
-					}
-					secOld.Key(keyEnUs.Name()).SetValue(newStr)
-				}
-			}
-		}
-		mustNoErr(iniOld.SaveTo(path))
-	}
-
-	fmt.Println("========")
-
-	for path, iniNew := range inisNew {
-		for _, sec := range iniNew.Sections() {
-			for _, key := range sec.Keys() {
-				str := sec.Key(key.Name()).String()
-				broken := strings.Contains(str, "\n")
-				broken = broken || strings.HasPrefix(str, "`") != strings.HasSuffix(str, "`")
-				broken = broken || strings.HasPrefix(str, "\"`")
-				broken = broken || strings.HasPrefix(str, "`\"")
-				broken = broken || strings.Count(str, `"`)%2 == 1
-				broken = broken || strings.Count(str, "`")%2 == 1
-				if broken && !brokenWarned.Contains(sec.Name()+"."+key.Name()) {
-					fmt.Printf("WARNING: found broken locale: %s , [%s] %s\n", path, sec.Name(), key.Name())
-					fmt.Printf("\tstr: %s\n", strings.ReplaceAll(str, "\n", "\\n"))
-					fmt.Println("----")
-				}
-			}
-		}
-	}
-}
diff --git a/go.mod b/go.mod
index 26a2b818efcea..d0d43b7aa13c5 100644
--- a/go.mod
+++ b/go.mod
@@ -38,6 +38,7 @@ require (
 	github.com/caddyserver/certmagic v0.24.0
 	github.com/charmbracelet/git-lfs-transfer v0.1.1-0.20251013092601-6327009efd21
 	github.com/chi-middleware/proxy v1.1.1
+	github.com/deckarep/golang-set/v2 v2.8.0
 	github.com/dimiro1/reply v0.0.0-20200315094148-d0136a4c9e21
 	github.com/dsnet/compress v0.0.2-0.20230904184137-39efe44ab707
 	github.com/dustin/go-humanize v1.0.1
diff --git a/go.sum b/go.sum
index 7490b3923c489..e8c74623986c4 100644
--- a/go.sum
+++ b/go.sum
@@ -256,6 +256,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc h1:U9qPSI2PIWSS1
 github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davidmz/go-pageant v1.0.2 h1:bPblRCh5jGU+Uptpz6LgMZGD5hJoOt7otgT454WvHn0=
 github.com/davidmz/go-pageant v1.0.2/go.mod h1:P2EDDnMqIwG5Rrp05dTRITj9z2zpGcD9efWSkTNKLIE=
+github.com/deckarep/golang-set/v2 v2.8.0 h1:swm0rlPCmdWn9mESxKOjWk8hXSqoxOp+ZlfuyaAdFlQ=
+github.com/deckarep/golang-set/v2 v2.8.0/go.mod h1:VAky9rY/yGXJOLEDv3OMci+7wtDpOF4IN+y82NBOac4=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/rVNCu3HqELle0jiPLLBs70cWOduZpkS1E78=
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
 github.com/dimiro1/reply v0.0.0-20200315094148-d0136a4c9e21 h1:PdsjTl0Cg+ZJgOx/CFV5NNgO1ThTreqdgKYiDCMHJwA=
diff --git a/models/actions/runner.go b/models/actions/runner.go
index 84398b143b8cf..5e08c94d121d3 100644
--- a/models/actions/runner.go
+++ b/models/actions/runner.go
@@ -115,6 +115,7 @@ func (r *ActionRunner) StatusName() string {
 }
 
 func (r *ActionRunner) StatusLocaleName(lang translation.Locale) string {
+	// i18n-check: actions.runners.status.*
 	return lang.TrString("actions.runners.status." + r.StatusName())
 }
 
diff --git a/models/actions/status.go b/models/actions/status.go
index 2b1d70613c71b..895fd52fb36de 100644
--- a/models/actions/status.go
+++ b/models/actions/status.go
@@ -43,6 +43,7 @@ func (s Status) String() string {
 
 // LocaleString returns the locale string name of the Status
 func (s Status) LocaleString(lang translation.Locale) string {
+	// i18n-check: actions.status.*
 	return lang.TrString("actions.status." + s.String())
 }
 
diff --git a/models/git/commit_status.go b/models/git/commit_status.go
index 2ae5937a3d8ff..6aad2af1c0896 100644
--- a/models/git/commit_status.go
+++ b/models/git/commit_status.go
@@ -210,6 +210,7 @@ func (status *CommitStatus) APIURL(ctx context.Context) string {
 
 // LocaleString returns the locale string name of the Status
 func (status *CommitStatus) LocaleString(lang translation.Locale) string {
+	// i18n-check: repo.commitstatus.*
 	return lang.TrString("repo.commitstatus." + status.State.String())
 }
 
diff --git a/models/issues/comment.go b/models/issues/comment.go
index f15618bf50088..1fc0adb126074 100644
--- a/models/issues/comment.go
+++ b/models/issues/comment.go
@@ -226,11 +226,13 @@ const (
 
 // LocaleString returns the locale string name of the role
 func (r RoleInRepo) LocaleString(lang translation.Locale) string {
+	// i18n-check: repo.issues.role.*
 	return lang.TrString("repo.issues.role." + string(r))
 }
 
 // LocaleHelper returns the locale tooltip of the role
 func (r RoleInRepo) LocaleHelper(lang translation.Locale) string {
+	// i18n-check: repo.issues.role.*_helper
 	return lang.TrString("repo.issues.role." + string(r) + "_helper")
 }
 
diff --git a/modules/auth/password/password.go b/modules/auth/password/password.go
index a1e101dd621cb..e0781cbf96f6e 100644
--- a/modules/auth/password/password.go
+++ b/modules/auth/password/password.go
@@ -128,6 +128,7 @@ func BuildComplexityError(locale translation.Locale) template.HTML {
 	buffer.WriteString("<ul>")
 	for _, c := range requiredList {
 		buffer.WriteString("<li>")
+		// i18n-check: form.password_*
 		buffer.WriteString(locale.TrString(c.TrNameOne))
 		buffer.WriteString("</li>")
 	}
diff --git a/modules/setting/config_provider.go b/modules/setting/config_provider.go
index 57dc23b17f7a5..a734f3bf8f523 100644
--- a/modules/setting/config_provider.go
+++ b/modules/setting/config_provider.go
@@ -348,23 +348,6 @@ func deprecatedSettingDB(rootCfg ConfigProvider, oldSection, oldKey string) {
 	}
 }
 
-// NewConfigProviderForLocale loads locale configuration from source and others. "string" if for a local file path, "[]byte" is for INI content
-func NewConfigProviderForLocale(source any, others ...any) (ConfigProvider, error) {
-	iniFile, err := ini.LoadSources(ini.LoadOptions{
-		IgnoreInlineComment:         true,
-		UnescapeValueCommentSymbols: true,
-		IgnoreContinuation:          true,
-	}, source, others...)
-	if err != nil {
-		return nil, fmt.Errorf("unable to load locale ini: %w", err)
-	}
-	iniFile.BlockMode = false
-	return &iniConfigProvider{
-		ini:             iniFile,
-		loadedFromEmpty: true,
-	}, nil
-}
-
 func init() {
 	ini.PrettyFormat = false
 }
diff --git a/modules/setting/config_provider_test.go b/modules/setting/config_provider_test.go
index 63121f0074094..dcbe280e824be 100644
--- a/modules/setting/config_provider_test.go
+++ b/modules/setting/config_provider_test.go
@@ -113,24 +113,6 @@ func TestNewConfigProviderFromFile(t *testing.T) {
 	assert.Equal(t, "[foo]\nk1 = a\n\n[bar]\nk1 = b\n", string(bs))
 }
 
-func TestNewConfigProviderForLocale(t *testing.T) {
-	// load locale from file
-	localeFile := t.TempDir() + "/locale.ini"
-	_ = os.WriteFile(localeFile, []byte(`k1=a`), 0o644)
-	cfg, err := NewConfigProviderForLocale(localeFile)
-	assert.NoError(t, err)
-	assert.Equal(t, "a", cfg.Section("").Key("k1").String())
-
-	// load locale from bytes
-	cfg, err = NewConfigProviderForLocale([]byte("k1=foo\nk2=bar"))
-	assert.NoError(t, err)
-	assert.Equal(t, "foo", cfg.Section("").Key("k1").String())
-	cfg, err = NewConfigProviderForLocale([]byte("k1=foo\nk2=bar"), []byte("k2=xxx"))
-	assert.NoError(t, err)
-	assert.Equal(t, "foo", cfg.Section("").Key("k1").String())
-	assert.Equal(t, "xxx", cfg.Section("").Key("k2").String())
-}
-
 func TestDisableSaving(t *testing.T) {
 	testFile := t.TempDir() + "/test.ini"
 	_ = os.WriteFile(testFile, []byte("k1=a\nk2=b"), 0o644)
diff --git a/modules/templates/i18n.go b/modules/templates/i18n.go
new file mode 100644
index 0000000000000..c67d95ecb34ed
--- /dev/null
+++ b/modules/templates/i18n.go
@@ -0,0 +1,141 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package templates
+
+import (
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+	"text/template"
+	"text/template/parse"
+
+	"code.gitea.io/gitea/modules/container"
+)
+
+func isI18nFunc(name string) bool {
+	return name == "ctx.Locale.Tr" || name == "ctx.Locale.TrN" || name == "ctx.Locale.TrString"
+}
+
+var i18nCheckPattern = regexp.MustCompile(`<!--\s*i18n-check:\s*([^>]+?)\s*-->`)
+
+func extractI18nKeys(node parse.Node) container.Set[string] {
+	keys, _ := collectI18nKeys(node, "")
+	return keys
+}
+
+func collectI18nKeys(node parse.Node, override string) (container.Set[string], string) {
+	switch n := node.(type) {
+	case *parse.WithNode:
+		keys, nextOverride := collectI18nKeys(n.List, override)
+		if n.Pipe != nil {
+			var pipeKeys container.Set[string]
+			pipeKeys, nextOverride = collectI18nKeys(n.Pipe, nextOverride)
+			keys = keys.Union(pipeKeys)
+		}
+		return keys, nextOverride
+	case *parse.ListNode:
+		var keys = container.Set[string]{}
+		pending := override
+		for _, sub := range n.Nodes {
+			var subKeys container.Set[string]
+			subKeys, pending = collectI18nKeys(sub, pending)
+			keys = keys.Union(subKeys)
+		}
+		return keys, pending
+	case *parse.TemplateNode: // ignore the file inclusion
+		fmt.Printf("Visiting node: %#v\n---\n%s\n---\n", node, node.String())
+		if n.Pipe != nil {
+			return collectI18nKeys(n.Pipe, override)
+		}
+		return container.Set[string]{}, override
+	case *parse.TextNode: // detect optional override hints
+		if hint, ok := extractI18nCheckOverride(string(n.Text)); ok {
+			return container.Set[string]{}, hint
+		}
+		return container.Set[string]{}, override
+	case *parse.IfNode:
+		keys, nextOverride := collectI18nKeys(n.List, override)
+		if n.ElseList != nil {
+			var elseKeys container.Set[string]
+			elseKeys, nextOverride = collectI18nKeys(n.ElseList, nextOverride)
+			keys = keys.Union(elseKeys)
+		}
+		return keys, nextOverride
+	case *parse.RangeNode:
+		keys, nextOverride := collectI18nKeys(n.List, override)
+		if n.Pipe != nil {
+			var pipeKeys container.Set[string]
+			pipeKeys, nextOverride = collectI18nKeys(n.Pipe, nextOverride)
+			keys = keys.Union(pipeKeys)
+		}
+		return keys, nextOverride
+	case *parse.ActionNode:
+		return collectI18nKeys(n.Pipe, override)
+	case *parse.PipeNode:
+		var keys = container.Set[string]{}
+		pending := override
+		for _, cmd := range n.Cmds {
+			var subKeys container.Set[string]
+			subKeys, pending = collectI18nKeys(cmd, pending)
+			keys = keys.Union(subKeys)
+		}
+		return keys, pending
+	case *parse.CommandNode:
+		if len(n.Args) >= 2 {
+			if ident, ok := n.Args[0].(*parse.ChainNode); ok && isI18nFunc(ident.String()) {
+				var keys = container.Set[string]{}
+				if override != "" {
+					keys.Add(strings.TrimSpace(override))
+					return keys, ""
+				}
+				for _, arg := range n.Args[1:] { // sometimes it will be `ctx.Locale.Tr (print "key")`
+					if str, ok := arg.(*parse.StringNode); ok {
+						keys.Add(str.Text)
+						if (ident.String() == "ctx.Locale.TrN" && len(keys) == 2) || (ident.String() != "ctx.Locale.TrN" && len(keys) == 1) {
+							return keys, override
+						}
+					} else if p, ok := arg.(*parse.PipeNode); ok {
+						for _, cmd := range p.Cmds {
+							if cmd.Args != nil && len(cmd.Args) > 0 {
+								for _, cmdArg := range cmd.Args {
+									if str, ok := cmdArg.(*parse.StringNode); ok {
+										keys.Add(str.Text)
+										if (ident.String() == "ctx.Locale.TrN" && len(keys) == 2) || (ident.String() != "ctx.Locale.TrN" && len(keys) == 1) {
+											return keys, override
+										}
+									}
+								}
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+	return container.Set[string]{}, override
+}
+
+func extractI18nCheckOverride(text string) (string, bool) {
+	matches := i18nCheckPattern.FindAllStringSubmatch(text, -1)
+	if len(matches) == 0 {
+		return "", false
+	}
+	return strings.TrimSpace(matches[len(matches)-1][1]), true
+}
+
+func FindTemplateKeys(p string) (container.Set[string], error) {
+	bs, err := os.ReadFile(p)
+	if err != nil {
+		return nil, err
+	}
+
+	// The template parser requires the function map otherwise it will return failure
+	t, err := template.New("test").Funcs(NewFuncMap()).Parse(string(bs))
+	if err != nil {
+		return nil, err
+	}
+
+	return extractI18nKeys(t.Root), nil
+}
diff --git a/modules/templates/i18n_test.go b/modules/templates/i18n_test.go
new file mode 100644
index 0000000000000..2bb9b7fd68d1e
--- /dev/null
+++ b/modules/templates/i18n_test.go
@@ -0,0 +1,148 @@
+package templates
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_FindTemplateKeys(t *testing.T) {
+	var kases = []struct {
+		path string
+		expectedKeys []string
+	}{
+		{
+			path : "../../templates/repo/issue/view_content/comments.tmpl",
+			expectedKeys : []string{
+				"repo.issues.remove_time_estimate_at",
+				"repo.issues.closed_at",
+				"repo.issues.force_push_codes",
+				"repo.issues.review.remove_review_request",
+				"repo.issues.add_assignee_at",
+				"repo.issues.self_assign_at",
+				"repo.issues.remove_project_at",
+				"repo.issues.dependency.removed_dependency",
+				"repo.issues.change_title_at",
+				"repo.pulls.reopened_at",
+				"repo.issues.remove_ref_at",
+				"repo.pulls.auto_merge_newly_scheduled_comment",
+				"repo.issues.remove_milestone_at",
+				"repo.issues.unpin_comment",
+				"repo.issues.change_milestone_at",
+				"repo.pulls.auto_merge_canceled_schedule_comment",
+				"repo.issues.remove_label",
+				"repo.issues.move_to_column_of_project",
+				"repo.issues.add_remove_labels",
+				"repo.issues.review.remove_review_request_self",
+				"repo.issues.comment_manually_pull_merged_at",
+				"repo.issues.commented_at",
+				"repo.issues.reopened_at",
+				"repo.pulls.closed_at",
+				"repo.issues.comment_pull_merged_at",
+				"repo.issues.ref_from",
+				"repo.issues.commit_ref_at",
+				"repo.issues.add_label",
+				"repo.issues.add_labels",
+				"repo.issues.remove_labels",
+				"repo.issues.add_milestone_at",
+				"repo.issues.remove_self_assignment",
+				"repo.issues.remove_assignee_at",
+				"repo.issues.delete_branch_at",
+				"repo.issues.start_tracking_history",
+				"repo.issues.stop_tracking_history",
+				"repo.issues.add_time_history",
+				"repo.issues.cancel_tracking_history",
+				"repo.issues.due_date_added",
+				"repo.issues.due_date_modified",
+				"repo.issues.due_date_remove",
+				"repo.issues.dependency.added_dependency",
+				"repo.issues.review.approve",
+				"repo.issues.review.comment",
+				"repo.issues.review.reject",
+				"repo.issues.review.dismissed_label",
+				"repo.migrated_from",
+				"repo.issues.review.left_comment",
+				"repo.issues.no_content",
+				"repo.issues.lock_with_reason",
+				"repo.issues.lock_no_reason",
+				"repo.issues.unlock_comment",
+				"repo.pulls.change_target_branch_at",
+				"repo.issues.del_time_history",
+				"repo.issues.review.add_review_request",
+				"repo.issues.push_commit_1",
+				"repo.issues.push_commits_n",
+				"repo.issues.force_push_compare",
+				"projects.deleted.display_name",
+				"projects.type-%d.display_name",
+				"repo.issues.change_project_at",
+				"repo.issues.add_project_at",
+				"repo.issues.review.dismissed",
+				"action.review_dismissed_reason",
+				"repo.issues.change_ref_at",
+				"repo.issues.add_ref_at",
+				"repo.issues.pin_comment",
+				"repo.issues.change_time_estimate_at",
+			},
+		},
+		{
+			path: "../../templates/repo/header.tmpl",
+			expectedKeys: []string{
+				 "repo.desc.archived",
+				 "repo.desc.private",
+				 "repo.desc.internal",
+				 "repo.desc.public_access",
+				 "repo.desc.template",
+				 "repo.desc.sha256",
+				 "repo.transfer.accept_desc",
+				 "repo.transfer.no_permission_to_accept",
+				 "repo.transfer.accept",
+				 "repo.transfer.reject_desc",
+				 "repo.transfer.no_permission_to_reject",
+				 "repo.transfer.reject",
+				"rss_feed",
+				 "repo.fork_guest_user",
+				 "repo.fork_from_self",
+				"repo.fork",
+				 "repo.already_forked",
+				 "repo.fork_to_different_account",
+				 "repo.mirror_from",
+				 "repo.mirror_sync",
+				 "repo.forked_from",
+				 "repo.generated_from",
+				"repo.code",
+				"repo.issues",
+				"repo.pulls",
+				"actions.actions",
+				"packages.title",
+				"repo.projects",
+				"repo.releases",
+				"repo.wiki",
+				"repo.activity",
+				"repo.settings",
+				"repo.migration_status",
+			},
+		},
+		{
+			path: "../../templates/repo/wiki/new.tmpl",
+			expectedKeys: []string{
+				"repo.wiki.page_content",
+				 "repo.wiki.save_page",
+				 "repo.wiki.new_page",
+				 "repo.wiki.new_page_button",
+				 "repo.wiki.page_title",
+				 "repo.wiki.page_name_desc",
+				 "repo.wiki.welcome",
+				 "repo.wiki.default_commit_message",
+				"cancel",
+			},
+		},
+	}
+
+	for _, kase := range kases {
+		t.Run(kase.path, func(t *testing.T) {
+			keys, err := FindTemplateKeys(kase.path)
+			assert.NoError(t, err)
+			assert.ElementsMatch(t, kase.expectedKeys, keys.Values())
+		})
+	}
+}
diff --git a/modules/translation/i18n/i18n.go b/modules/translation/i18n/i18n.go
index fae41927dbfdb..d6f973a5bf2cf 100644
--- a/modules/translation/i18n/i18n.go
+++ b/modules/translation/i18n/i18n.go
@@ -33,6 +33,8 @@ type LocaleStore interface {
 	HasLang(langName string) bool
 	// AddLocaleByIni adds a new language to the store
 	AddLocaleByJSON(langName, langDesc string, source, moreSource []byte) error
+	// Keys returns all translation keys in the store
+	Keys() []string
 }
 
 // ResetDefaultLocales resets the current default locales
diff --git a/modules/translation/i18n/localestore.go b/modules/translation/i18n/localestore.go
index 98934e2835928..38c70421cf7dd 100644
--- a/modules/translation/i18n/localestore.go
+++ b/modules/translation/i18n/localestore.go
@@ -123,6 +123,14 @@ func (store *localeStore) Locale(lang string) (Locale, bool) {
 	return l, found
 }
 
+func (store *localeStore) Keys() []string {
+	keys := make([]string, 0, len(store.trKeyToIdxMap))
+	for k := range store.trKeyToIdxMap {
+		keys = append(keys, k)
+	}
+	return keys
+}
+
 func (store *localeStore) Close() error {
 	return nil
 }
@@ -163,6 +171,7 @@ func (l *locale) TrHTML(trKey string, trArgs ...any) template.HTML {
 			args[i] = template.HTMLEscapeString(fmt.Sprint(v))
 		}
 	}
+	// i18n-check: ignore
 	return template.HTML(l.TrString(trKey, args...))
 }
 
diff --git a/modules/translation/translation.go b/modules/translation/translation.go
index 85a67ba2af87a..93ee10acf9c78 100644
--- a/modules/translation/translation.go
+++ b/modules/translation/translation.go
@@ -241,6 +241,7 @@ func (l *locale) TrN(cnt any, key1, keyN string, args ...any) template.HTML {
 	} else if t, ok := cnt.(int64); ok {
 		c = t
 	} else {
+		// i18n-check: ignore
 		return l.Tr(keyN, args...)
 	}
 
diff --git a/modules/util/error.go b/modules/util/error.go
index 4c2566a2a33f5..647f38143015e 100644
--- a/modules/util/error.go
+++ b/modules/util/error.go
@@ -91,6 +91,7 @@ func (w *errorTranslatableWrapper) Error() string { return w.err.Error() }
 func (w *errorTranslatableWrapper) Unwrap() error { return w.err }
 
 func (w *errorTranslatableWrapper) Translate(t ErrorLocaleTranslator) template.HTML {
+	// i18n-check: ignore
 	return t.Tr(w.trKey, w.trArgs...)
 }
 
diff --git a/modules/web/middleware/binding.go b/modules/web/middleware/binding.go
index ee4eca976e367..dfaa8bca1ced4 100644
--- a/modules/web/middleware/binding.go
+++ b/modules/web/middleware/binding.go
@@ -104,8 +104,10 @@ func Validate(errs binding.Errors, data map[string]any, f Form, l translation.Lo
 
 			trName := field.Tag.Get("locale")
 			if len(trName) == 0 {
+				// i18n-check: form.*
 				trName = l.TrString("form." + field.Name)
 			} else {
+				// i18n-check: ignore
 				trName = l.TrString(trName)
 			}
 
diff --git a/options/locale/locale_en-US.json b/options/locale/locale_en-US.json
index 417698544f52c..7c85ad82f5fe4 100644
--- a/options/locale/locale_en-US.json
+++ b/options/locale/locale_en-US.json
@@ -48,21 +48,16 @@
   "webauthn_error_duplicated": "The security key is not permitted for this request. Please make sure that the key is not already registered.",
   "webauthn_error_empty": "You must set a name for this key.",
   "webauthn_error_timeout": "Timeout reached before your key could be read. Please reload this page and retry.",
-  "webauthn_reload": "Reload",
   "repository": "Repository",
   "organization": "Organization",
   "mirror": "Mirror",
   "issue_milestone": "Milestone",
   "new_repo": "New Repository",
   "new_migrate": "New Migration",
-  "new_mirror": "New Mirror",
   "new_fork": "New Repository Fork",
   "new_org": "New Organization",
-  "new_project": "New Project",
   "new_project_column": "New Column",
-  "manage_org": "Manage Organizations",
   "admin_panel": "Site Administration",
-  "account_settings": "Account Settings",
   "settings_title": "Settings",
   "your_profile": "Profile",
   "your_starred": "Starred",
@@ -253,6 +248,8 @@
   "install.repo_path_helper": "Remote Git repositories will be saved to this directory.",
   "install.lfs_path": "Git LFS Root Path",
   "install.lfs_path_helper": "Files tracked by Git LFS will be stored in this directory. Leave empty to disable.",
+  "install.invalid_lfs_path": "The Git LFS root path is invalid: %v",
+  "install.lfs_jwt_secret_failed": "Failed to generate Git LFS JWT secret: %v",
   "install.run_user": "Run As Username",
   "install.run_user_helper": "The operating system username that Gitea runs as. Note that this user must have access to the repository root path.",
   "install.domain": "Server Domain",
@@ -946,6 +943,7 @@
   "settings.visibility.limited_tooltip": "Visible only to authenticated users",
   "settings.visibility.private": "Private",
   "settings.visibility.private_tooltip": "Visible only to members of organizations you have joined",
+  "settings.adopt": "Adopt Repository",
   "repo.new_repo_helper": "A repository contains all project files, including revision history. Already hosting one elsewhere? <a href=\"%s\">Migrate repository.</a>",
   "repo.owner": "Owner",
   "repo.owner_helper": "Some organizations may not show up in the dropdown due to a maximum repository count limit.",
diff --git a/routers/web/admin/admin.go b/routers/web/admin/admin.go
index 0cd13acf6012b..efa6c67d88d94 100644
--- a/routers/web/admin/admin.go
+++ b/routers/web/admin/admin.go
@@ -180,6 +180,7 @@ func DashboardPost(ctx *context.Context) {
 			task := cron.GetTask(form.Op)
 			if task != nil {
 				go task.RunWithUser(ctx.Doer, nil)
+				// i18n-check: admin.dashboard.*
 				ctx.Flash.Success(ctx.Tr("admin.dashboard.task.started", ctx.Tr("admin.dashboard."+form.Op)))
 			} else {
 				ctx.Flash.Error(ctx.Tr("admin.dashboard.task.unknown", form.Op))
diff --git a/routers/web/repo/activity.go b/routers/web/repo/activity.go
index 4cfe879032a0d..9ed9c5126b756 100644
--- a/routers/web/repo/activity.go
+++ b/routers/web/repo/activity.go
@@ -46,6 +46,7 @@ func Activity(ctx *context.Context) {
 	ctx.Data["DateFrom"] = timeFrom
 	ctx.Data["DateUntil"] = timeUntil
 	ctx.Data["Period"] = period
+	// i18n-check: repo.activity.period.*
 	ctx.Data["PeriodText"] = ctx.Tr("repo.activity.period." + period)
 
 	canReadCode := ctx.Repo.CanRead(unit.TypeCode)
diff --git a/routers/web/repo/editor_apply_patch.go b/routers/web/repo/editor_apply_patch.go
index 357c6f3a21aa2..b9ac1a3c56861 100644
--- a/routers/web/repo/editor_apply_patch.go
+++ b/routers/web/repo/editor_apply_patch.go
@@ -41,6 +41,7 @@ func NewDiffPatchPost(ctx *context.Context) {
 		Committer:    parsed.GitCommitter,
 	})
 	if err != nil {
+		// i18n-check: ignore
 		err = util.ErrorWrapTranslatable(err, "repo.editor.fail_to_apply_patch")
 	}
 	if err != nil {
diff --git a/routers/web/repo/editor_cherry_pick.go b/routers/web/repo/editor_cherry_pick.go
index 605a35b10087f..d169d764da6e4 100644
--- a/routers/web/repo/editor_cherry_pick.go
+++ b/routers/web/repo/editor_cherry_pick.go
@@ -73,6 +73,7 @@ func CherryPickPost(ctx *context.Context) {
 			opts.Content = buf.String()
 			_, err = files.ApplyDiffPatch(ctx, ctx.Repo.Repository, ctx.Doer, opts)
 			if err != nil {
+				// i18n-check: ignore
 				err = util.ErrorWrapTranslatable(err, "repo.editor.fail_to_apply_patch")
 			}
 		}
diff --git a/routers/web/repo/editor_error.go b/routers/web/repo/editor_error.go
index e1473a34b397c..29f932cc9fc7b 100644
--- a/routers/web/repo/editor_error.go
+++ b/routers/web/repo/editor_error.go
@@ -41,42 +41,57 @@ func editorHandleFileOperationError(ctx *context_service.Context, targetBranchNa
 	if errAs := util.ErrorAsTranslatable(err); errAs != nil {
 		ctx.JSONError(errAs.Translate(ctx.Locale))
 	} else if errAs, ok := errorAs[git.ErrNotExist](err); ok {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.file_modifying_no_longer_exists", errAs.RelPath))
 	} else if errAs, ok := errorAs[git_model.ErrLFSFileLocked](err); ok {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.upload_file_is_locked", errAs.Path, errAs.UserName))
 	} else if errAs, ok := errorAs[files_service.ErrFilenameInvalid](err); ok {
 		ctx.JSONError(ctx.Tr("repo.editor.filename_is_invalid", errAs.Path))
 	} else if errAs, ok := errorAs[files_service.ErrFilePathInvalid](err); ok {
 		switch errAs.Type {
 		case git.EntryModeSymlink:
+			// i18n-check: ignore
 			ctx.JSONError(ctx.Tr("repo.editor.file_is_a_symlink", errAs.Path))
 		case git.EntryModeTree:
+			// i18n-check: ignore
 			ctx.JSONError(ctx.Tr("repo.editor.filename_is_a_directory", errAs.Path))
 		case git.EntryModeBlob:
+			// i18n-check: ignore
 			ctx.JSONError(ctx.Tr("repo.editor.directory_is_a_file", errAs.Path))
 		default:
+			// i18n-check: ignore
 			ctx.JSONError(ctx.Tr("repo.editor.filename_is_invalid", errAs.Path))
 		}
 	} else if errAs, ok := errorAs[files_service.ErrRepoFileAlreadyExists](err); ok {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.file_already_exists", errAs.Path))
 	} else if errAs, ok := errorAs[git.ErrBranchNotExist](err); ok {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.branch_does_not_exist", errAs.Name))
 	} else if errAs, ok := errorAs[git_model.ErrBranchAlreadyExists](err); ok {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.branch_already_exists", errAs.BranchName))
 	} else if files_service.IsErrCommitIDDoesNotMatch(err) {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.commit_id_not_matching"))
 	} else if files_service.IsErrCommitIDDoesNotMatch(err) || git.IsErrPushOutOfDate(err) {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("repo.editor.file_changed_while_editing", ctx.Repo.RepoLink+"/compare/"+util.PathEscapeSegments(ctx.Repo.CommitID)+"..."+util.PathEscapeSegments(targetBranchName)))
 	} else if errAs, ok := errorAs[*git.ErrPushRejected](err); ok {
 		if errAs.Message == "" {
+			// i18n-check: ignore
 			ctx.JSONError(ctx.Tr("repo.editor.push_rejected_no_message"))
 		} else {
+			// i18n-check: ignore
 			editorHandleFileOperationErrorRender(ctx, ctx.Locale.TrString("repo.editor.push_rejected"), ctx.Locale.TrString("repo.editor.push_rejected_summary"), errAs.Message)
 		}
 	} else if errors.Is(err, util.ErrNotExist) {
+		// i18n-check: ignore
 		ctx.JSONError(ctx.Tr("error.not_found"))
 	} else {
 		setting.PanicInDevOrTesting("unclear err %T: %v", err, err)
+		// i18n-check: ignore
 		editorHandleFileOperationErrorRender(ctx, ctx.Locale.TrString("repo.editor.failed_to_commit"), ctx.Locale.TrString("repo.editor.failed_to_commit_summary"), err.Error())
 	}
 }
diff --git a/routers/web/repo/migrate.go b/routers/web/repo/migrate.go
index 8f4adb2ad220f..68ed2fccec4d8 100644
--- a/routers/web/repo/migrate.go
+++ b/routers/web/repo/migrate.go
@@ -315,10 +315,11 @@ func MigrateStatus(ctx *context.Context) {
 		var translatableMessage admin_model.TranslatableMessage
 		if err := json.Unmarshal([]byte(message), &translatableMessage); err != nil {
 			translatableMessage = admin_model.TranslatableMessage{
-				Format: "migrate.migrating_failed.error",
+				Format: "repo.migrate.migrating_failed.error",
 				Args:   []any{task.Message},
 			}
 		}
+		// i18n-check: repo.migrate.migrating_failed.*
 		message = ctx.Locale.TrString(translatableMessage.Format, translatableMessage.Args...)
 	}
 
diff --git a/routers/web/repo/pull.go b/routers/web/repo/pull.go
index cff501ad71d92..1be8b626d3ebc 100644
--- a/routers/web/repo/pull.go
+++ b/routers/web/repo/pull.go
@@ -1187,8 +1187,8 @@ func MergePullRequest(ctx *context.Context) {
 		} else if pull_service.IsErrMergeConflicts(err) {
 			conflictError := err.(pull_service.ErrMergeConflicts)
 			flashError, err := ctx.RenderToHTML(tplAlertDetails, map[string]any{
-				"Message": ctx.Tr("repo.editor.merge_conflict"),
-				"Summary": ctx.Tr("repo.editor.merge_conflict_summary"),
+				"Message": ctx.Tr("repo.pulls.merge_conflict"),
+				"Summary": ctx.Tr("repo.pulls.merge_conflict_summary"),
 				"Details": utils.SanitizeFlashErrorString(conflictError.StdErr) + "<br>" + utils.SanitizeFlashErrorString(conflictError.StdOut),
 			})
 			if err != nil {
diff --git a/routers/web/user/setting/profile.go b/routers/web/user/setting/profile.go
index 35303221fe463..01c5831d88530 100644
--- a/routers/web/user/setting/profile.go
+++ b/routers/web/user/setting/profile.go
@@ -71,7 +71,7 @@ func ProfilePost(ctx *context.Context) {
 
 	if form.Name != "" {
 		if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureChangeUsername) {
-			ctx.Flash.Error(ctx.Tr("user.form.change_username_disabled"))
+			ctx.Flash.Error(ctx.Tr("form.change_username_disabled"))
 			ctx.Redirect(setting.AppSubURL + "/user/settings")
 			return
 		}
@@ -107,7 +107,7 @@ func ProfilePost(ctx *context.Context) {
 
 	if form.FullName != "" {
 		if user_model.IsFeatureDisabledWithLoginType(ctx.Doer, setting.UserFeatureChangeFullName) {
-			ctx.Flash.Error(ctx.Tr("user.form.change_full_name_disabled"))
+			ctx.Flash.Error(ctx.Tr("form.change_full_name_disabled"))
 			ctx.Redirect(setting.AppSubURL + "/user/settings")
 			return
 		}
diff --git a/services/actions/workflow.go b/services/actions/workflow.go
index 4f72aad11244a..10461b6103200 100644
--- a/services/actions/workflow.go
+++ b/services/actions/workflow.go
@@ -48,6 +48,7 @@ func DispatchActionWorkflow(ctx reqctx.RequestContext, doer *user_model.User, re
 	if workflowID == "" {
 		return util.ErrorWrapTranslatable(
 			util.NewNotExistErrorf("workflowID is empty"),
+			// i18n-check: ignore
 			"actions.workflow.not_found", workflowID,
 		)
 	}
@@ -55,6 +56,7 @@ func DispatchActionWorkflow(ctx reqctx.RequestContext, doer *user_model.User, re
 	if ref == "" {
 		return util.ErrorWrapTranslatable(
 			util.NewNotExistErrorf("ref is empty"),
+			// i18n-check: ignore
 			"form.target_ref_not_exist", ref,
 		)
 	}
@@ -65,6 +67,7 @@ func DispatchActionWorkflow(ctx reqctx.RequestContext, doer *user_model.User, re
 	if cfg.IsWorkflowDisabled(workflowID) {
 		return util.ErrorWrapTranslatable(
 			util.NewPermissionDeniedErrorf("workflow is disabled"),
+			// i18n-check: ignore
 			"actions.workflow.disabled",
 		)
 	}
@@ -84,6 +87,7 @@ func DispatchActionWorkflow(ctx reqctx.RequestContext, doer *user_model.User, re
 	if err != nil {
 		return util.ErrorWrapTranslatable(
 			util.NewNotExistErrorf("ref %q doesn't exist", ref),
+			// i18n-check: ignore
 			"form.target_ref_not_exist", ref,
 		)
 	}
@@ -124,6 +128,7 @@ func DispatchActionWorkflow(ctx reqctx.RequestContext, doer *user_model.User, re
 	if entry == nil {
 		return util.ErrorWrapTranslatable(
 			util.NewNotExistErrorf("workflow %q doesn't exist", workflowID),
+			// i18n-check: ignore
 			"actions.workflow.not_found", workflowID,
 		)
 	}
diff --git a/services/asymkey/commit.go b/services/asymkey/commit.go
index 6286588a60827..7f183485f63f8 100644
--- a/services/asymkey/commit.go
+++ b/services/asymkey/commit.go
@@ -102,6 +102,7 @@ func parseCommitWithGPGSignature(ctx context.Context, c *git.Commit, committer *
 			return &asymkey_model.CommitVerification{
 				CommittingUser: committer,
 				Verified:       false,
+				// i18n-check: gpg.error.failed_retrieval_gpg_keys
 				Reason:         "gpg.error.failed_retrieval_gpg_keys",
 			}
 		}
diff --git a/services/context/base.go b/services/context/base.go
index 4baea95ccf9f2..4adab4e967b01 100644
--- a/services/context/base.go
+++ b/services/context/base.go
@@ -183,6 +183,7 @@ func (b *Base) ServeContent(r io.ReadSeeker, opts *ServeHeaderOptions) {
 }
 
 func (b *Base) Tr(msg string, args ...any) template.HTML {
+	// i18n-check: ignore
 	return b.Locale.Tr(msg, args...)
 }
 
diff --git a/services/cron/setting.go b/services/cron/setting.go
index 6dad88830abb5..09fac9166293b 100644
--- a/services/cron/setting.go
+++ b/services/cron/setting.go
@@ -70,6 +70,7 @@ func (b *BaseConfig) DoNoticeOnSuccess() bool {
 // Please note the `status` string will be concatenated with `admin.dashboard.cron.` and `admin.dashboard.task.` to provide locale messages. Similarly `name` will be composed with `admin.dashboard.` to provide the locale name for the task.
 func (b *BaseConfig) FormatMessage(locale translation.Locale, name, status, doer string, args ...any) string {
 	realArgs := make([]any, 0, len(args)+2)
+	// i18n-check: admin.dashboard.*
 	realArgs = append(realArgs, locale.TrString("admin.dashboard."+name))
 	if doer == "" {
 		realArgs = append(realArgs, "(Cron)")
@@ -80,7 +81,9 @@ func (b *BaseConfig) FormatMessage(locale translation.Locale, name, status, doer
 		realArgs = append(realArgs, args...)
 	}
 	if doer == "" {
+		// i18n-check: admin.dashboard.cron.*
 		return locale.TrString("admin.dashboard.cron."+status, realArgs...)
 	}
+	// i18n-check: admin.dashboard.task.*
 	return locale.TrString("admin.dashboard.task."+status, realArgs...)
 }
diff --git a/services/cron/tasks.go b/services/cron/tasks.go
index 885ab10228539..eb46c89470f9b 100644
--- a/services/cron/tasks.go
+++ b/services/cron/tasks.go
@@ -170,6 +170,7 @@ func RegisterTask(name string, config Config, fun func(context.Context, *user_mo
 	log.Debug("Registering task: %s", name)
 
 	i18nKey := "admin.dashboard." + name
+	// i18n-check: admin.dashboard.*
 	if value := translation.NewLocale("en-US").TrString(i18nKey); value == i18nKey {
 		return fmt.Errorf("translation is missing for task %q, please add translation for %q", name, i18nKey)
 	}
diff --git a/services/mailer/mail_workflow_run.go b/services/mailer/mail_workflow_run.go
index 37891028121c6..a1f7958926fa7 100644
--- a/services/mailer/mail_workflow_run.go
+++ b/services/mailer/mail_workflow_run.go
@@ -111,6 +111,7 @@ func composeAndSendActionsWorkflowRunStatusEmail(ctx context.Context, repo *repo
 		case actions_model.StatusCancelled:
 			runStatusTrString = "mail.repo.actions.jobs.all_cancelled"
 		}
+		// i18n-check: mail.repo.actions.jobs.*
 		subject := fmt.Sprintf("%s: %s (%s)", locale.TrString(subjectTrString), run.WorkflowID, base.ShortSha(run.CommitSHA))
 		var mailBody bytes.Buffer
 		if err := LoadedTemplates().BodyTemplates.ExecuteTemplate(&mailBody, string(tplWorkflowRun), map[string]any{
diff --git a/services/release/notes.go b/services/release/notes.go
index c9dc75af70d08..ff0823f866f50 100644
--- a/services/release/notes.go
+++ b/services/release/notes.go
@@ -40,6 +40,7 @@ func GenerateReleaseNotes(ctx context.Context, repo *repo_model.Repository, gitR
 
 	baseCommit, err := gitRepo.GetCommit(opts.PreviousTag)
 	if err != nil {
+		// i18n-check: ignore
 		return "", util.ErrorWrapTranslatable(util.ErrNotExist, "repo.release.generate_notes_tag_not_found", opts.TagName)
 	}
 
@@ -70,6 +71,7 @@ func resolveHeadCommit(gitRepo *git.Repository, tagName, tagTarget string) (*git
 
 	commit, err := gitRepo.GetCommit(ref)
 	if err != nil {
+		// i18n-check: ignore
 		return nil, util.ErrorWrapTranslatable(util.ErrNotExist, "repo.release.generate_notes_target_not_found", ref)
 	}
 	return commit, nil
diff --git a/services/repository/branch.go b/services/repository/branch.go
index a580208af6a8f..f363bb5c42ea9 100644
--- a/services/repository/branch.go
+++ b/services/repository/branch.go
@@ -822,6 +822,7 @@ func DeleteBranchAfterMerge(ctx context.Context, doer *user_model.User, prID int
 	}
 	if pr.HeadRepo == nil {
 		// Forked repository has already been deleted
+		// i18n-check: ignore
 		return util.ErrorWrapTranslatable(util.ErrNotExist, "repo.branch.deletion_failed", "(deleted-repo):"+pr.HeadBranch)
 	}
 	if err = pr.HeadRepo.LoadOwner(ctx); err != nil {
@@ -834,6 +835,7 @@ func DeleteBranchAfterMerge(ctx context.Context, doer *user_model.User, prID int
 	}
 
 	errFailedToDelete := func(err error) error {
+		// i18n-check: ignore
 		return util.ErrorWrapTranslatable(err, "repo.branch.deletion_failed", fullBranchName)
 	}
 
@@ -882,6 +884,7 @@ func DeleteBranchAfterMerge(ctx context.Context, doer *user_model.User, prID int
 		return errFailedToDelete(err)
 	}
 	if headCommitID != branchCommitID {
+		// i18n-check: ignore
 		return util.ErrorWrapTranslatable(util.ErrUnprocessableContent, "repo.branch.delete_branch_has_new_commits", fullBranchName)
 	}
 
diff --git a/templates/admin/cron.tmpl b/templates/admin/cron.tmpl
index 4d01ce51eb6d9..20a030e2495bc 100644
--- a/templates/admin/cron.tmpl
+++ b/templates/admin/cron.tmpl
@@ -21,7 +21,7 @@
 					{{range .Entries}}
 						<tr>
 							<td><button type="submit" class="ui primary button" name="op" value="{{.Name}}" title="{{ctx.Locale.Tr "admin.dashboard.operation_run"}}">{{svg "octicon-triangle-right"}}</button></td>
-							<td>{{ctx.Locale.Tr (printf "admin.dashboard.%s" .Name)}}</td>
+							<td><!-- i18n-check: admin.dashboard.* -->{{ctx.Locale.Tr (printf "admin.dashboard.%s" .Name)}}</td>
 							<td>{{.Spec}}</td>
 							<td>{{DateUtils.FullTime .Next}}</td>
 							<td>{{if gt .Prev.Year 1}}{{DateUtils.FullTime .Prev}}{{else}}-{{end}}</td>
diff --git a/templates/repo/actions/status.tmpl b/templates/repo/actions/status.tmpl
index 1e5465a97fbd6..1854b62eebe87 100644
--- a/templates/repo/actions/status.tmpl
+++ b/templates/repo/actions/status.tmpl
@@ -4,6 +4,7 @@
 -->
 {{- $size := Iif .size .size 16 -}}
 {{- $className := Iif .className .className "" -}}
+<!-- i18n-check: actions.status.* -->
 <span data-tooltip-content="{{ctx.Locale.Tr (printf "actions.status.%s" .status)}}">
 {{if eq .status "success"}}
 	{{svg "octicon-check-circle-fill" $size (printf "text green %s" $className)}}
diff --git a/templates/repo/editor/commit_form.tmpl b/templates/repo/editor/commit_form.tmpl
index 10872f8af7452..315c6447f32d9 100644
--- a/templates/repo/editor/commit_form.tmpl
+++ b/templates/repo/editor/commit_form.tmpl
@@ -6,6 +6,7 @@
 			<span data-tooltip-content="{{ctx.Locale.Tr "repo.signing.will_sign" .CommitFormOptions.SigningKeyFormDisplay}}">{{svg "octicon-lock" 24}}</span>
 			{{ctx.Locale.Tr "repo.editor.commit_signed_changes"}}
 		{{- else}}
+			<!-- i18n-check: repo.signing.wont_sign.* -->
 			<span title="{{ctx.Locale.Tr (printf "repo.signing.wont_sign.%s" .CommitFormOptions.WontSignReason)}}">{{svg "octicon-unlock" 24}}</span>
 			{{ctx.Locale.Tr "repo.editor.commit_changes"}}
 		{{- end}}
diff --git a/templates/repo/issue/view_content/comments.tmpl b/templates/repo/issue/view_content/comments.tmpl
index 0eeb10cba7dfd..e545cb5f40600 100644
--- a/templates/repo/issue/view_content/comments.tmpl
+++ b/templates/repo/issue/view_content/comments.tmpl
@@ -561,6 +561,7 @@
 					{{if .OldProject}}
 						{{$tooltip := ctx.Locale.Tr "projects.deleted.display_name"}}
 						{{if not .OldProject.IsGhost}}
+							<!-- i18n-check: projects.type-*.display_name -->
 							{{$tooltip = ctx.Locale.Tr (printf "projects.type-%d.display_name" .OldProject.Type)}}
 						{{end}}
 						{{$oldProjectDisplayHtml = HTMLFormat `<span data-tooltip-content="%s">%s</span>` $tooltip .OldProject.Title}}
diff --git a/templates/repo/migrate/migrate.tmpl b/templates/repo/migrate/migrate.tmpl
index 79ac5cc8a1143..49025e3070b53 100644
--- a/templates/repo/migrate/migrate.tmpl
+++ b/templates/repo/migrate/migrate.tmpl
@@ -20,6 +20,7 @@
 								{{.Title}}
 							</div>
 							<div class="description tw-text-center tw-text-balance">
+								<!-- i18n-check: repo.migrate.*.description -->
 								{{ctx.Locale.Tr (printf "repo.migrate.%s.description" .Name)}}
 							</div>
 						</div>
diff --git a/templates/webhook/new.tmpl b/templates/webhook/new.tmpl
index 8ef33df25b45b..f974e9d3089f2 100644
--- a/templates/webhook/new.tmpl
+++ b/templates/webhook/new.tmpl
@@ -3,6 +3,7 @@
 	<div class="ui right type dropdown">
 		<div class="text tw-flex tw-items-center">
 			{{template "shared/webhook/icon" (dict "Size" 20 "HookType" .ctxData.HookType)}}
+			<!-- i18n-check: repo.settings.web_hook_name_* -->
 			{{ctx.Locale.Tr (print "repo.settings.web_hook_name_" .ctxData.HookType)}}
 		</div>
 		{{svg "octicon-triangle-down" 14 "dropdown icon"}}
diff --git a/tools/i18n/check.go b/tools/i18n/check.go
new file mode 100644
index 0000000000000..453d7fbbb6a4a
--- /dev/null
+++ b/tools/i18n/check.go
@@ -0,0 +1,241 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build ignore
+
+package main
+
+import (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+
+	"code.gitea.io/gitea/modules/glob"
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/templates"
+	"code.gitea.io/gitea/modules/translation/i18n"
+)
+
+func searchTranslationKeyInDirs(keys []string) ([]bool, []string, error) {
+	res := make([]bool, len(keys))
+	untranslatedKeysSum := make([]string, 0, 20)
+	for _, dir := range []string{
+		"cmd",
+		"models",
+		"modules",
+		"routers",
+		"services",
+		"templates",
+	} {
+		untranslatedKeys, err := checkTranslationKeysInDir(dir, keys, &res)
+		if err != nil {
+			return nil, nil, err
+		}
+
+		untranslatedKeysSum = append(untranslatedKeysSum, untranslatedKeys...)
+	}
+	return res, untranslatedKeysSum, nil
+}
+
+func checkTranslationKeysInDir(dir string, keys []string, res *[]bool) ([]string, error) {
+	var untranslatedSum []string
+	if err := filepath.WalkDir(dir, func(path string, d os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		switch {
+		case d.IsDir():
+			return nil
+		// check unused and untranslated keys in the file
+		case strings.HasSuffix(d.Name(), ".go") && !strings.HasSuffix(d.Name(), "_test.go"):
+			untranslatedKeys, err := checkTranslationKeysInGoFile(dir, path, keys, res)
+			if err != nil {
+				return err
+			}
+			untranslatedSum = append(untranslatedSum, untranslatedKeys...)
+		case strings.HasSuffix(d.Name(), ".tmpl"):
+			fmt.Println("----checking template file:", path)
+			untranslatedKeysInTmpl, err := checkTranslationKeysInTemplateFile(dir, path, keys, res)
+			if err != nil {
+				return err
+			}
+			untranslatedSum = append(untranslatedSum, untranslatedKeysInTmpl...)
+		}
+		return nil
+	}); err != nil {
+		return nil, err
+	}
+	return untranslatedSum, nil
+}
+
+func checkTranslationKeysInCall(path string, fset *token.FileSet, astf *ast.File, call *ast.CallExpr, arg ast.Expr, keys []string, res *[]bool) string {
+	if lit, ok := arg.(*ast.BasicLit); ok && lit.Kind == token.STRING {
+		key := strings.Trim(lit.Value, `"`)
+		idx := slices.Index(keys, key)
+		if idx == -1 {
+			return key
+		}
+		(*res)[idx] = true
+		return ""
+	}
+
+	var lastCg *ast.CommentGroup
+	for _, cg := range astf.Comments {
+		if cg.End() < call.Pos() {
+			if lastCg == nil || cg.End() > lastCg.End() {
+				lastCg = cg
+			}
+		}
+	}
+	if lastCg == nil {
+		fmt.Printf("no comment found for a dynamic translation key: %s:%d\n", path, fset.Position(call.Pos()).Line)
+		os.Exit(1)
+		return ""
+	}
+
+	transKeyMatch, ok := strings.CutPrefix(lastCg.Text(), "i18n-check:")
+	if !ok {
+		fmt.Printf("no comment found for a dynamic translation key: %s:%d\n", path, fset.Position(call.Pos()).Line)
+		os.Exit(1)
+		return ""
+	}
+	transKeyMatch = strings.TrimSpace(transKeyMatch)
+	switch transKeyMatch {
+	case "ignore": // i18n-check: ignore
+		return ""
+	default: // i18n-check: <transKeyMatch>
+		g := glob.MustCompile(transKeyMatch)
+		found := false
+		for i, key := range keys {
+			if g.Match(key) {
+				(*res)[i] = true
+				found = true
+			}
+		}
+		if !found {
+			return transKeyMatch
+		}
+	}
+	return ""
+}
+
+func checkTranslationKeysInGoFile(dir, path string, keys []string, res *[]bool) ([]string, error) {
+	if filepath.Ext(path) != ".go" || strings.HasSuffix(path, "_test.go") {
+		return nil, nil
+	}
+
+	var untranslated []string
+	fs := token.NewFileSet()
+	node, err := parser.ParseFile(fs, path, nil, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+
+	ast.Inspect(node, func(n ast.Node) bool {
+		call, ok := n.(*ast.CallExpr)
+		if !ok {
+			return true
+		}
+		if funIdent, ok := call.Fun.(*ast.SelectorExpr); ok {
+			switch funIdent.Sel.Name {
+			case "Tr", "TrString":
+				if len(call.Args) >= 1 {
+					if key := checkTranslationKeysInCall(path, fs, node, call, call.Args[0], keys, res); key != "" {
+						untranslated = append(untranslated, key)
+					}
+				}
+			case "TrN":
+				if len(call.Args) >= 3 {
+					if key := checkTranslationKeysInCall(path, fs, node, call, call.Args[1], keys, res); key != "" {
+						untranslated = append(untranslated, key)
+					}
+					if key := checkTranslationKeysInCall(path, fs, node, call, call.Args[2], keys, res); key != "" {
+						untranslated = append(untranslated, key)
+					}
+				}
+			}
+		}
+		return true
+	})
+
+	return untranslated, err
+}
+
+func checkTranslationKeysInTemplateFile(dir, path string, keys []string, res *[]bool) ([]string, error) {
+	untranslatedKeys := []string{}
+	keysFoundInTempl, err := templates.FindTemplateKeys(path)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Println("==== keys found in template:", keysFoundInTempl)
+	for _, key := range keysFoundInTempl.Values() {
+		idx := slices.Index(keys, key)
+		if idx == -1 {
+			found := false
+			for _, uk := range keys {
+				if glob.MustCompile(key).Match(uk) {
+					found = true
+					break
+				}
+			}
+			if !found {
+				untranslatedKeys = append(untranslatedKeys, key)
+			}
+		} else {
+			(*res)[idx] = true
+		}
+	}
+	return untranslatedKeys, nil
+}
+
+func main() {
+	if len(os.Args) != 1 {
+		println("usage: clean-locales")
+		os.Exit(1)
+	}
+
+	fileContent, err := os.ReadFile("options/locale/locale_en-US.json")
+	if err != nil {
+		panic(err)
+	}
+	store := i18n.NewLocaleStore()
+	if err = store.AddLocaleByJSON("English", "en-US", fileContent, nil); err != nil {
+		log.Error("Failed to read translation from en-US: %v", err)
+	}
+
+	keys := store.Keys()
+	results, untranslatedKeys, err := searchTranslationKeyInDirs(keys)
+	if err != nil {
+		panic(err)
+	}
+
+	var found bool
+	for i, result := range results {
+		if !result {
+			if !found {
+				println("unused locale keys found\n---")
+				found = true
+			}
+			println(keys[i])
+		}
+	}
+
+	if len(untranslatedKeys) > 0 {
+		found = true
+		println("\nuntranslated locale keys found\n---")
+	}
+	for _, key := range untranslatedKeys {
+		println(key)
+	}
+	println()
+
+	if found {
+		os.Exit(1) // exit with error if any unused locale key is found
+	}
+}