SHARE vs USGS Earthquake Hazards Program

SHARE (now internally rebranded "trove", version 26.0.0 as of this check) is the Center for Open Science's free aggregator of metadata about research and scholarly activity, pulling in tens of millions of records from sources like CrossRef and OSF and re-indexing them for keyless search. Its v2 API exposes an Elasticsearch-backed search endpoint plus RSS and Atom feeds, all reachable with no registration.

The USGS Earthquake Hazards Program's FDSNWS Event Web Service is a keyless REST API for querying the agency's global earthquake catalog by region, time window, magnitude, or depth, returning real-time and historical seismic event data. Requests default to QuakeML XML but can also return GeoJSON, CSV, or KML via a format parameter, and the whole service is free and unauthenticated, run directly by the federal government.