yes, any extension that is in the DB here is safe to use . there are only a few "official" extensions that the staff here has created/tested etc.
the rest of them have been sumbitted by others for testing by the staff. once they have been tested and validated then they are put in the DB for extensions and made available for download from here.
I am available for custom work on a donation basis. Please send me a PM with your needs.
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OK, so what's the speed of dark?