Cross Platform Mod API.
mod.io API is a free Games & Comics API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
We're here to enhance your game by unlocking mods or user generated content (UGC). Whether it's empowering players to create new skins, game modes, VFX, SFX or anything else, our service provides the framework for player customization and creativity within your game.
Details from docs.mod.io.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Mojang / Minecraft API
Monster Hunter World data
Free Sudoku puzzles, printable Sudoku worksheets and online play: https://sudokumax.com
Yes. The mod.io API is listed in the Games & Comics category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The mod.io API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the mod.io API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The mod.io API is served over HTTPS, so it's safe to use in production.