Poedit (formerly poEdit) is a free, open source and cross-platform gettext catalog (.po file) editor to aid in the process of language localisation. It is built for Unix+GTK or Windows with wxWidgets and licensed under the terms of the MIT license.
Here is a brief features list:
- Unlike other catalogs editors, Poedit shows data in very compact way. Entries are arranged in a list, so that you can easily navigate large catalogs and immediately get an idea about how big part of the catalog is already translated, what needs translating and which parts are only translated in a "fuzzy" way.
- Runs on Unix and Windows systems.
- Plural forms support.
- Features whitespaces highlighting.
- Fuzzy and untranslated records are highlighted and displayed at the top of the list.
- Automatic compilation of .mo files (optional).
- Automatic headers update.
- References browser lets you see where and in what context is the string used.
- You can use Poedit to scan source code for translatable strings.
- Integration with KDE and GNOME desktops. Neither of these environments is required, support for them is strictly optional.
- UTF-8 support. Poedit understands all encodings supported by operating system and works in Unicode internally.
- Support for conversion between line-ending formats (useful if you need to edit catalogs by hand under Windows).
- Translation memory automates translation of frequent phrases. Poedit can reuse translation data from all your PO, MO and RPM files.
- Search dialog for quick navigation in the catalog.
- Comments editing.
- Catalogs manager.
- Unicode support on Windows NT/2000/XP (partial Unicode support on Windows 9x). Full Unicode support under Unix with GTK+ 2.x.
- Spellchecking (GTK+ 2.x).
See also 
External links