Bruno,
you find concentrated information about Pootle on the
Pootle Wikipedia site. There you find all sort of links e.g. their homepage or the code base at github. Pootle is also hosted on
Sourceforge.
As Pootle is a Web Translation tool, you need a running web server for it, the operating system doesn't depend. The web server has to be capable to generate dynamic content from Python code. It could be a local system at your LAN for home or test use, but for public services you need a sever at your preferred ISP.
You need a SQL server too, iirc there are several server supported e.g. MySQL or PostgreSQL.
Traffic and disc space depends much on the number of languages, the translation project and the usage.
For LibreCAD Pootle is installed on our librecad.org server, which is a Debian Linux server and we us a MySQL server on this machine for the database.
On our server Pootle uses about 40MB and the LibreCAD files are about 270MB. I can't say what the additional packages like Translation Tool Kit or Django Web Framework consume or how much space is used by the database.
Regards
Armin
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