[app4soft]

Also, «Symbian Archive»[0,1] project has a lot of mirrors of Symbian source & software.

Here is a list of active Symbian software developers* (+ links to its projects).[2]

P.S. I'm luckily archived/mirrored LCG's X-plore[3] & ProfiMail[4] apps source repos in time when it was released into Public Domain by LonelyCatGames* team (now official repos is disabled).

[0] https://mrrosset.github.io/Symbian-Archive/index.html

[1] https://github.com/mrRosset/Symbian-Archive

[2] https://github.com/mrRosset/Symbian-Archive/issues/10

[3] https://github.com/Symbian9/X-plore_free

[4] https://github.com/Symbian9/ProfiMail_free