An i18n middleware for the Express.js framework.

Usage no npm install needed!

<script type="module">
  import expressGettext from '';



Translation middleware for express.js using Gettext and PO files.

I couldn't find any existing middleware that used PO files as the translation source (without converting them to JSON first), so there is a simple middleware that loads PO files, and exposes a simple gettext translate method on the response and app object to allow translations to be looked up from the server and in views.


The middleware exposes some methods on the app object. They use on the application's "default" locale:

app.setLocale -> Method to set the default locale
app.getLocale || app.locals.getLocale || app.getDefaultLocale -> Methods to get the default locale
app[alias] || app.locals[alias] -> translate method (using the default locale)

Properties on the ```res`` object:

res.setLocale -> Method to set the current locale 
res.getLocale || res.locals.getLocale -> Method to get the current locale
res.getDefaultLocale -> Method to get the default (application) locale
res[alias] || res.locals[alias] -> translate method


    directory: -> The directory of PO files
    useAcceptedLanguageHeader: true
    alias -> The alias of the translate method (default 'gettext')

Locale detection

The middleware also has crude locale detection based upon the acceptedLanguageHeader, which can be toggled with the useAcceptedLanguageHeader option.


var express = require('express');
var gettext = require('../express-gettext')

var app = express();

// Configuration
app.set('port', process.env.PORT || 8080);
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');

// Gettext configuration
app.use(gettext(app, {
    directory: __dirname + '/locales',
    useAcceptedLanguageHeader: true

app.use(express.static(__dirname + '/public'));

app.get('/', function(req, res) {

    if(req.query && req.query.locale) {


app.listen(app.get('port'), function() {
    console.log("App listening on port " + app.get('port'));