diff --git a/cvt.go b/cvt.go
new file mode 100644
index 0000000..4e55ad7
--- /dev/null
+++ b/cvt.go
@@ -0,0 +1,14 @@
+package cvt
+
+// Bool convert an interface to a bool type, with default value
+func Bool(v interface{}, def ...bool) bool {
+	if v, err := BoolE(v); err == nil {
+		return v
+	}
+
+	if len(def) > 0 {
+		return def[0]
+	}
+
+	return false
+}
diff --git a/cvt_test.go b/cvt_test.go
new file mode 100644
index 0000000..55028ef
--- /dev/null
+++ b/cvt_test.go
@@ -0,0 +1,113 @@
+package cvt_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/shockerli/cvt"
+)
+
+func TestBool_HasDefault(t *testing.T) {
+	tests := []struct {
+		input  interface{}
+		def    bool
+		expect bool
+	}{
+		// supported value, def is not used, def != expect
+		{0, true, false},
+		{float64(0.00), true, false},
+		{int(0.00), true, false},
+		{int64(0.00), true, false},
+		{uint(0.00), true, false},
+		{uint64(0.00), true, false},
+		{uint8(0.00), true, false},
+		{nil, true, false},
+		{"false", true, false},
+		{"FALSE", true, false},
+		{"False", true, false},
+		{"f", true, false},
+		{"F", true, false},
+		{false, true, false},
+		{"off", true, false},
+		{"Off", true, false},
+		{[]byte("Off"), true, false},
+		{aliasTypeInt_0, true, false},
+		{&aliasTypeInt_0, true, false},
+		{aliasTypeString_0, true, false},
+		{&aliasTypeString_0, true, false},
+		{aliasTypeString_off, true, false},
+		{&aliasTypeString_off, true, false},
+
+		{[]int{}, true, false},
+		{[]string{}, true, false},
+		{[...]string{}, true, false},
+		{map[int]int{}, true, false},
+		{map[string]string{}, true, false},
+
+		{"true", false, true},
+		{"TRUE", false, true},
+		{"True", false, true},
+		{"t", false, true},
+		{"T", false, true},
+		{1, false, true},
+		{true, false, true},
+		{-1, false, true},
+		{"on", false, true},
+		{"On", false, true},
+		{0.01, false, true},
+		{aliasTypeInt_1, false, true},
+		{&aliasTypeInt_1, false, true},
+		{aliasTypeString_1, false, true},
+		{&aliasTypeString_1, false, true},
+		{aliasTypeString_on, false, true},
+		{&aliasTypeString_on, false, true},
+
+		{[]int{1, 2, 3}, false, true},
+		{[]string{"a", "b", "c"}, false, true},
+		{[...]string{"a", "b", "c"}, false, true},
+		{map[int]int{1: 111, 2: 222}, false, true},
+		{map[string]string{"a": "aaa"}, false, true},
+
+		// unsupported value, def == expect
+		{"hello", true, true},
+		{"hello", false, false},
+		{testing.T{}, true, true},
+		{testing.T{}, false, false},
+		{&testing.T{}, true, true},
+		{&testing.T{}, false, false},
+	}
+
+	for i, tt := range tests {
+		msg := fmt.Sprintf("i = %d, input[%+v], def[%+v], expect[%+v]", i, tt.input, tt.def, tt.expect)
+
+		v := cvt.Bool(tt.input, tt.def)
+		assert.Equal(t, tt.expect, v, msg)
+	}
+}
+
+func TestBool_BaseLine(t *testing.T) {
+	tests := []struct {
+		input  interface{}
+		expect bool
+	}{
+		{testing.T{}, false},
+		{&testing.T{}, false},
+		{[]int{}, false},
+		{[]int{1, 2, 3}, true},
+		{[]string{}, false},
+		{[]string{"a", "b", "c"}, true},
+		{[...]string{}, false},
+		{map[int]string{}, false},
+		{aliasTypeString_8d15_minus, true},
+		{&aliasTypeString_8d15_minus, true},
+	}
+
+	for i, tt := range tests {
+		msg := fmt.Sprintf("i = %d, input[%+v], expect[%+v]", i, tt.input, tt.expect)
+
+		v := cvt.Bool(tt.input)
+		assert.Equal(t, tt.expect, v, msg)
+	}
+}
diff --git a/cvte.go b/cvte.go
new file mode 100644
index 0000000..0017f14
--- /dev/null
+++ b/cvte.go
@@ -0,0 +1,117 @@
+package cvt
+
+import (
+	"fmt"
+	"reflect"
+	"strconv"
+	"strings"
+)
+
+// BoolE convert an interface to a bool type
+func BoolE(val interface{}) (bool, error) {
+	v, rk, rv := Indirect(val)
+
+	switch vv := v.(type) {
+	case bool:
+		return vv, nil
+	case int, int8, int16, int32, int64:
+		return rv.Int() != 0, nil
+	case uint, uint8, uint16, uint32, uint64:
+		return rv.Uint() != 0, nil
+	case float32, float64:
+		return rv.Float() != 0, nil
+	case []byte:
+		return str2bool(string(vv))
+	case string:
+		return str2bool(vv)
+	case nil:
+		return false, nil
+	}
+
+	switch rk {
+	// by elem length
+	case reflect.Array, reflect.Slice, reflect.Map:
+		return rv.Len() > 0, nil
+	}
+
+	return false, err(val, "bool")
+}
+
+// returns the boolean value represented by the string
+func str2bool(str string) (bool, error) {
+	if val, err := strconv.ParseBool(str); err == nil {
+		return val, nil
+	} else if val, err := strconv.ParseFloat(str, 64); err == nil {
+		return val != 0, nil
+	}
+
+	switch strings.ToLower(strings.TrimSpace(str)) {
+	case "on":
+		return true, nil
+	case "off":
+		return false, nil
+	default:
+		return false, err(str, "bool")
+	}
+}
+
+// Indirect returns the value with base type
+func Indirect(a interface{}) (val interface{}, k reflect.Kind, v reflect.Value) {
+	if a == nil {
+		return
+	}
+
+	t := reflect.TypeOf(a)
+	v = reflect.ValueOf(a)
+	k = t.Kind()
+
+	switch t.Kind() {
+	case reflect.Ptr:
+		for v.Kind() == reflect.Ptr && !v.IsNil() {
+			v = v.Elem()
+		}
+		return Indirect(v.Interface())
+	case reflect.Bool:
+		val = v.Bool()
+	case reflect.Int:
+		val = int(v.Int())
+	case reflect.Int8:
+		val = int8(v.Int())
+	case reflect.Int16:
+		val = int16(v.Int())
+	case reflect.Int32:
+		val = int32(v.Int())
+	case reflect.Int64:
+		val = v.Int()
+	case reflect.Uint:
+		val = uint(v.Uint())
+	case reflect.Uint8:
+		val = uint8(v.Uint())
+	case reflect.Uint16:
+		val = uint16(v.Uint())
+	case reflect.Uint32:
+		val = uint32(v.Uint())
+	case reflect.Uint64:
+		val = v.Uint()
+	case reflect.Uintptr:
+		val = uintptr(v.Uint())
+	case reflect.Float32:
+		val = float32(v.Float())
+	case reflect.Float64:
+		val = v.Float()
+	case reflect.Complex64:
+		val = complex64(v.Complex())
+	case reflect.Complex128:
+		val = v.Complex()
+	case reflect.String:
+		val = v.String()
+	default:
+		val = v.Interface()
+	}
+
+	return
+}
+
+func err(val interface{}, t string) error {
+	return fmt.Errorf("unable to convert %#v of type %T to %s", val, val, t)
+}
diff --git a/cvte_test.go b/cvte_test.go
new file mode 100644
index 0000000..27daa90
--- /dev/null
+++ b/cvte_test.go
@@ -0,0 +1,121 @@
+package cvt_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/shockerli/cvt"
+)
+
+// alias type: int
+type AliasTypeInt int
+
+var (
+	aliasTypeInt_0 AliasTypeInt = 0
+	aliasTypeInt_1 AliasTypeInt = 1
+)
+
+// alias type: string
+type AliasTypeString string
+
+var (
+	aliasTypeString_0          AliasTypeString = "0"
+	aliasTypeString_1          AliasTypeString = "1"
+	aliasTypeString_8d15       AliasTypeString = "8.15"
+	aliasTypeString_8d15_minus AliasTypeString = "-8.15"
+	aliasTypeString_on         AliasTypeString = "on"
+	aliasTypeString_off        AliasTypeString = "off"
+)
+
+func TestBoolE(t *testing.T) {
+	tests := []struct {
+		input  interface{}
+		expect bool
+		isErr  bool
+	}{
+		// true/scale
+		{0, false, false},
+		{float64(0.00), false, false},
+		{int(0.00), false, false},
+		{int64(0.00), false, false},
+		{uint(0.00), false, false},
+		{uint64(0.00), false, false},
+		{uint8(0.00), false, false},
+		{nil, false, false},
+		{"false", false, false},
+		{"FALSE", false, false},
+		{"False", false, false},
+		{"f", false, false},
+		{"F", false, false},
+		{false, false, false},
+		{"off", false, false},
+		{"Off", false, false},
+		{"0", false, false},
+		{"0.00", false, false},
+		{[]byte("Off"), false, false},
+		{aliasTypeInt_0, false, false},
+		{&aliasTypeInt_0, false, false},
+		{aliasTypeString_0, false, false},
+		{&aliasTypeString_0, false, false},
+		{aliasTypeString_off, false, false},
+		{&aliasTypeString_off, false, false},
+
+		// false/slice/array/map
+		{[]int{}, false, false},
+		{[]string{}, false, false},
+		{[...]string{}, false, false},
+		{map[int]int{}, false, false},
+		{map[string]string{}, false, false},
+
+		// true/scale
+		{"true", true, false},
+		{"TRUE", true, false},
+		{"True", true, false},
+		{"t", true, false},
+		{"T", true, false},
+		{1, true, false},
+		{true, true, false},
+		{-1, true, false},
+		{"on", true, false},
+		{"On", true, false},
+		{0.01, true, false},
+		{"0.01", true, false},
+		{aliasTypeInt_1, true, false},
+		{&aliasTypeInt_1, true, false},
+		{aliasTypeString_1, true, false},
+		{&aliasTypeString_1, true, false},
+		{aliasTypeString_on, true, false},
+		{&aliasTypeString_on, true, false},
+
+		// true/slice/array/map
+		{[]int{1, 2, 3}, true, false},
+		{[]string{"a", "b", "c"}, true, false},
+		{[...]string{"a", "b", "c"}, true, false},
+		{map[int]int{1: 111, 2: 222}, true, false},
+		{map[string]string{"a": "aaa"}, true, false},
+
+		// errors
+		{"hello", false, true},
+		{testing.T{}, false, true},
+		{&testing.T{}, false, true},
+	}
+
+	for i, tt := range tests {
+		msg := fmt.Sprintf("i = %d, input[%+v], expect[%+v], isErr[%+v]", i, tt.input, tt.expect, tt.isErr)
+
+		v, err := cvt.BoolE(tt.input)
+		if tt.isErr {
+			assert.Error(t, err, msg)
+			continue
+		}
+
+		assert.NoError(t, err, msg)
+		assert.Equal(t, tt.expect, v, msg)
+
+		// Non-E test with no default value:
+		v = cvt.Bool(tt.input)
+		assert.Equal(t, tt.expect, v, msg)
+	}
+}
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..e053fa2
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,10 @@
+module github.com/shockerli/cvt
+
+go 1.15
+
+require (
+	github.com/davecgh/go-spew v1.1.1
+	github.com/stretchr/objx v0.3.0 // indirect
+	github.com/stretchr/testify v1.7.0
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..246b4aa
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,17 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.3.0 h1:NGXK3lHquSN08v5vWalVI/L8XU9hdzE/G6xsrze47As=
+github.com/stretchr/objx v0.3.0/go.mod h1:qt09Ya8vawLte6SNmTgCsAVtYtaKzEcn8ATUoHMkEqE=
+github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b h1:h8qDotaEPuJATrMmW04NCwg7v22aHH28wwpauUhK9Oo=
+gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=