diff --git a/src/runtime/shared/inspect.ts b/src/runtime/shared/inspect.ts
index c5eb0c9..10a9397 100644
--- a/src/runtime/shared/inspect.ts
+++ b/src/runtime/shared/inspect.ts
@@ -10,6 +10,7 @@ import RuleNoErrorResponse from './inspections/no-error-response-status'
 import RuleNoJavascript from './inspections/no-javascript'
 import RuleNoMissingHref from './inspections/no-missing-href'
 import RuleNoNonAsciiChars from './inspections/no-non-ascii-chars'
+import RuleNoUppercaseChars from './inspections/no-uppercase-chars'
 import RuleNoWhitespace from './inspections/no-whitespace'
 import RuleTrailingSlash from './inspections/trailing-slash'
 import RuleRedirects from './redirects'
@@ -25,6 +26,7 @@ export const AllInspections = [
   RuleNoDocumentRelative(),
   RuleNoJavascript(),
   RuleTrailingSlash(),
+  RuleNoUppercaseChars(),
   RuleAbsoluteSiteUrls(),
   RuleRedirects(),
   RuleDescriptiveLinkText(),
diff --git a/src/runtime/shared/inspections/no-uppercase-chars.ts b/src/runtime/shared/inspections/no-uppercase-chars.ts
new file mode 100644
index 0000000..0b829cf
--- /dev/null
+++ b/src/runtime/shared/inspections/no-uppercase-chars.ts
@@ -0,0 +1,18 @@
+import { defineRule } from './util'
+
+export default function RuleNoUppercaseChars() {
+  return defineRule({
+    id: 'no-uppercase-chars',
+    test({ report, link }) {
+      if (link.match(/[A-Z]/)) {
+        report({
+          name: 'no-uppercase-chars',
+          scope: 'warning',
+          message: 'Links should not contain uppercase characters.',
+          fix: link.toLowerCase(),
+          fixDescription: 'Convert to lowercase.',
+        })
+      }
+    },
+  })
+}
diff --git a/test/unit/rules/no-uppercase-chars.test.ts b/test/unit/rules/no-uppercase-chars.test.ts
new file mode 100644
index 0000000..7d83e18
--- /dev/null
+++ b/test/unit/rules/no-uppercase-chars.test.ts
@@ -0,0 +1,46 @@
+import type { RuleTestContext } from '../../../src/runtime/types'
+import { describe, expect, it } from 'vitest'
+import RuleNoUppercaseChars from '../../../src/runtime/shared/inspections/no-uppercase-chars'
+import { runRule } from './util'
+
+describe('rule no-uppercase-chars', () => {
+  it('works', () => {
+    expect(runRule({ link: 'https://example.com/PAGE' } as RuleTestContext, RuleNoUppercaseChars())).toMatchInlineSnapshot(`
+      {
+        "error": [],
+        "fix": "https://example.com/page",
+        "link": "https://example.com/PAGE",
+        "passes": false,
+        "textContent": undefined,
+        "warning": [
+          {
+            "fix": "https://example.com/page",
+            "fixDescription": "Convert to lowercase.",
+            "message": "Links should not contain uppercase characters.",
+            "name": "no-uppercase-chars",
+            "scope": "warning",
+          },
+        ],
+      }
+    `)
+
+    expect(runRule({ link: '/this/IS/a/TEEST' } as RuleTestContext, RuleNoUppercaseChars())).toMatchInlineSnapshot(`
+      {
+        "error": [],
+        "fix": "/this/is/a/teest",
+        "link": "/this/IS/a/TEEST",
+        "passes": false,
+        "textContent": undefined,
+        "warning": [
+          {
+            "fix": "/this/is/a/teest",
+            "fixDescription": "Convert to lowercase.",
+            "message": "Links should not contain uppercase characters.",
+            "name": "no-uppercase-chars",
+            "scope": "warning",
+          },
+        ],
+      }
+    `)
+  })
+})