From personal experience: possibly Twitter. Having a presence there has given me several serious offers to interview, for jobs worth having (FAANG and similar).
The folks in my field (ML/applied math/scientific computing) are all on there, and moreover those reaching out to me are always technical folks rather than recruiters.
(Twitter gets a bad rap, but the academic/dev parts of it are the single best way I've found to track the Zeitgeist of fields and topics I'm interested in.)
'tech twitter' is full of junior developers, developer advocates, and students, all trying to sell e-books to each other or virtue signal their way into a dev advocate role. I only found content creator and tech influencer sales pitches.
This is definitely true, but then I also see more experienced developers and researchers tweeting about these people making fun of them and calling them on their bullshit.
I think tech Twitter quality is heavily dependent on being thoughtful of who you follow.
The folks in my field (ML/applied math/scientific computing) are all on there, and moreover those reaching out to me are always technical folks rather than recruiters.
(Twitter gets a bad rap, but the academic/dev parts of it are the single best way I've found to track the Zeitgeist of fields and topics I'm interested in.)