Seafile and its desktop and mobile clients are published under the GPLv3.
The Seafile server's web end, i.e. Seahub, is published under the Apache License.
Google Group: https://groups.google.com/forum/?fromgroups#!forum/seafile
IRC: #seafile on freenode
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Find the existing issues that fit your situation if any, or create a new issue. We are using github as our issue tracer https://github.com/haiwen/seafile/issues?state=open
Join us on Google Group: https://groups.google.com/forum/?fromgroups#!forum/seafile
The source code of seafile is ISO/IEC 9899:1999 (E) (a.k.a. C99) compatible. Take a look at code standard.