Come see #devfleet on the tweetfleet slack. https://www.fuzzwork.co.uk/tweetfleet-slack-invites/ for an invite.
https://developers.eveonline.com/ contains useful resources, and is where you register new applications.
https://esi.tech.ccp.is/latest/ is the root of ESI , the EVE Swagger Interface (API)
https://eveonline-third-party-documentation.readthedocs.io/en/latest/ is crowdsourced documentation for Eve’s api
https://www.fuzzwork.co.uk/dump/ has conversions of the Eve SDE into mysql, postgres, sqlite and CSV.
https://github.com/devfleet/awesome-eve has other resources.