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).

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")

// If use go:embed
//go:embed locale.*.toml
var LocaleFS embed.FS

bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
bundle.LoadMessageFileFS(LocaleFS, "locale.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.

The goi18n command manages message files used by the i18n package.

go install -v github.com/nicksnyder/go-i18n/v2/goi18n@latest
goi18n -help

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."

1. Create an empty message file for the language that you want to add (e.g. translate.es.toml).

2. Run goi18n merge active.en.toml translate.es.toml to populate translate.es.toml with the messages to be translated.

   # translate.es.toml
   [HelloPerson]
   hash = "sha1-5b49bfdad81fedaeefb224b0ffc2acc58b09cff5"
   other = "Hello {{.Name}}"

3. After translate.es.toml has been translated, rename it to active.es.toml.

   # active.es.toml
   [HelloPerson]
   hash = "sha1-5b49bfdad81fedaeefb224b0ffc2acc58b09cff5"
   other = "Hola {{.Name}}"

4. Load active.es.toml into your bundle.

   bundle.RegisterUnmarshalFunc("toml", toml.Unmarshal)
   bundle.LoadMessageFile("active.es.toml")

If you have added new messages to your program:

1. Run goi18n extract to update active.en.toml with the new messages.
2. Run goi18n merge active.*.toml to generate updated translate.*.toml files.
3. Translate all the messages in the translate.*.toml files.
4. Run goi18n merge active.*.toml translate.*.toml to merge the translated messages into the active message files.

• Read the documentation.
• Look at the code examples and tests.
• Look at an example application.

go-i18n is available under the MIT license. See the LICENSE file for more info.