Science & Math · head-to-head
arcsecond.io vs USGS Water Services
Arcsecond.io is the cloud API behind Arcsecond.local, a multi-user platform observatories run to manage telescopes, night logs, and data packages, but it still exposes the project's original public astronomy-lookup endpoints for object coordinates and exoplanets. Those endpoints are keyless and return live-synced records — /exoplanets/ pulls current rows from the NASA Exoplanet Archive. Paid tiers apply only to running a private observatory instance; the public data-lookup endpoints stay free.
USGS Water Services is a keyless REST API serving real-time and historical streamflow, groundwater, and water-quality readings from thousands of USGS monitoring sites across the US, in WaterML XML, JSON, or the legacy tab-delimited RDB format. The agency has announced it will decommission this API family in early 2027 in favor of its new Water Data APIs (api.waterdata.usgs.gov), with no degradation planned before August 2026 — new integrations should target the successor service.
| arcsecond.io | USGS Water Services | |
|---|---|---|
| Authentication | None | None |
| Pricing | freemium | free |
| Formats | JSON | JSON, XML, RDB |
| CORS | yes | yes |
| HTTPS | Yes | Yes |
USGS Water Services supports 3 response formats, while arcsecond.io offers fewer — pick USGS Water Services for more integration flexibility.