A developer tool is the one product type with somewhere better to go than the general boards. Start with Show HN, always, and not for the link, which is nofollow: the thread is the most direct product feedback you can get for free, and what people say there should rewrite your landing page before you submit anywhere else. Then Product Hunt and Peerlist for reach, in that order if you have an audience and the other way round if you do not.
After that the list narrows to places that only take engineering work, which is the point of them. DevHunt is developer tools only and charges $49 for a launch week. DevPages holds 77 hand-picked tools and a human emails you either way, which is rarer than it should be. DevTool.io states a developers-only bar on the form itself. MCP Directory reads your public repository to build the entry, so a closed-source or hosted-only server cannot get in at all. Boilerplate Hunt takes starter kits and nothing else. Awesome Tools wants DR 30 before it will look.
Across the 12 platforms on this list, median approval time is 6 days, 10 of 12 give dofollow backlinks, 9 are free to submit. Median domain rating: 43.