go-i18n 
go-i18n is a Go package and a command that helps you translate Go programs into multiple languages.
- Supports pluralized strings for all 200+ languages in the Unicode Common Locale Data Repository (CLDR).
- Code and tests are automatically generated from CLDR data.
- Supports strings with named variables using text/template syntax.
- Supports message files of any format (e.g. JSON, TOML, YAML).
Package i18n 
The i18n package provides support for looking up messages according to a set of locale preferences.
import "github.com/nicksnyder/go-i18n/v2/i18n"
Create a Bundle to use for the lifetime of your application.
bundle := i18n.NewBundle(language.English)
Load translations into your bundle during initialization.
bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
bundle.LoadMessageFile("es.toml")
Create a Localizer to use for a set of language preferences.
func(w http.ResponseWriter, r *http.Request) {
lang := r.FormValue("lang")
accept := r.Header.Get("Accept-Language")
localizer := i18n.NewLocalizer(bundle, lang, accept)
}
Use the Localizer to lookup messages.
localizer.Localize(&i18n.LocalizeConfig{
DefaultMessage: &i18n.Message{
ID: "PersonCats",
One: "{{.Name}} has {{.Count}} cat.",
Other: "{{.Name}} has {{.Count}} cats.",
},
TemplateData: map[string]interface{}{
"Name": "Nick",
"Count": 2,
},
PluralCount: 2,
}) // Nick has 2 cats.
Command goi18n
The goi18n command manages message files used by the i18n package.
go get -u github.com/nicksnyder/go-i18n/v2/goi18n
goi18n -help
Extracting messages
Use goi18n extract to extract all i18n.Message struct literals in Go source files to a message file for translation.
# active.en.toml
[PersonCats]
description = "The number of cats a person has"
one = "{{.Name}} has {{.Count}} cat."
other = "{{.Name}} has {{.Count}} cats."
Translating a new language
-
Create an empty message file for the language that you want to add (e.g.
translate.es.toml). -
Run
goi18n merge active.en.toml translate.es.tomlto populatetranslate.es.tomlwith the mesages to be translated.# translate.es.toml [HelloPerson] hash = "sha1-5b49bfdad81fedaeefb224b0ffc2acc58b09cff5" other = "Hello {{.Name}}" -
After
translate.es.tomlhas been translated, rename it toactive.es.toml.# active.es.toml [HelloPerson] hash = "sha1-5b49bfdad81fedaeefb224b0ffc2acc58b09cff5" other = "Hola {{.Name}}" -
Load
active.es.tomlinto your bundle.bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal) bundle.LoadMessageFile("active.es.toml")
Translating new messages
If you have added new messages to your program:
- Run
goi18n extractto updateactive.en.tomlwith the new messages. - Run
goi18n merge active.*.tomlto generate updatedtranslate.*.tomlfiles. - Translate all the messages in the
translate.*.tomlfiles. - Run
goi18n merge active.*.toml translate.*.tomlto merge the translated messages into the active message files.
For more information and examples:
- Read the documentation.
- Look at the code examples and tests.
- Look at an example application.
License
go-i18n is available under the MIT license. See the LICENSE file for more info.