Open5e

Open5e is both a rules website and a building block. Players can search Fifth Edition creatures, spells and rules, while developers can request the same material through a documented API. Version 2 supports broad text search, per-resource filtering, ordering, pagination and selecting only needed fields. Every item carries document information, allowing an application to restrict results to a particular SRD or compatible source. The website and server code are open source, which makes the project useful for encounter tools, reference apps and experiments that need legally reusable data.

Open does not mean complete. Product material that was never released under an applicable open license cannot appear, and third-party OGL books vary in design and editing. API version 1 is deprecated, so old integrations require review. Developers also need to preserve source and license information instead of flattening everything into an unexplained database. Open5e is an excellent foundation when provenance filters are part of the interface; it is not a substitute for content a publisher has kept outside the SRD.