diff --git a/README.md b/README.md
index a76c7db..9daf270 100644
--- a/README.md
+++ b/README.md
@@ -5,3 +5,24 @@ There is nothing stored on the server except the words.
 ## Database
 Database config option is set in the dbconfig.php file,
 example is in dbconfig_empty.php.
+This software is developped with PostgreSQL,
+I don't know if it is working with others DB management systems.
+
+## Libraries
+
+### php-i18n
+
+The internationalization is made possible by
+[Philipp Schröer (php-i18n project)](https://github.com/Philipp15b/php-i18n).
+For now it's only in french but the traduction should be easy.
+
+### Wordcloud2
+
+The display of the words cloud is done by the Wordcloud2 javascript
+code, made by
+[Timothy Guan-tin Chien](http://timdream.org/wordcloud2.js/).
+
+### Soundex_fr
+
+The words comparison is made with PHP tools and the work of
+Florent Bruneau on [the french translation of soundex](http://blog.mymind.fr/blog/2007/03/15/soundex-francais/).