Satellite data sources and APIs compared

Five public places to get satellite data, side by side. Which ones make you register, which publish a real API, what the free limits actually are, and what you are allowed to redistribute. Every figure below was read off the provider’s own documentation.

CelesTrak is one of the sources this catalog is built from, so read any row that favours us with that in mind. The full upstream list is on the sources page.

Side by side

Comparison of satellite data providers
Feature	OrbitalWiki	CelesTrak	Space-Track.org	N2YO	Heavens-Above
Run by	OrbitalWiki	Dr. T.S. Kelso, CelesTrak (501(c)(3) non-profit)	U.S. Space Force, 18th Space Defense Squadron	N2YO.com	Chris Peat, Heavens-Above GmbH
Account required	No	No	Yes	Yes	No
Machine-readable API	Yes	Yes	Yes	Yes	No
Bulk download	Yes	Yes	Yes	No	No
Free limit	No key needed to read; 1,000 requests a day with a free key	No published number; a usage policy applies	Under 30 requests a minute and 300 an hour; orbital data once an hour	Per endpoint per hour: 1,000 element sets or positions, 100 pass predictions	No API to limit
Data terms	ODbL-1.0, attribution required	CelesTrak usage policy	US Government terms; element sets and the catalog may be redistributed with citation	No licence stated; free key, do not work around the caps	Website terms; no data feed offered
Per-field source shown	Yes	No	No	No	No

Provider documentation checked 2026-08-03.

One at a time

OrbitalWiki vs CelesTrakThe long-running public source for orbital element sets and the satellite catalog, run as a non-profit. No account, no key, and the files are updated continuously.OrbitalWiki vs Space-Track.orgThe U.S. Space Force catalog, and the origin of most public orbital data. Free to use, but you must register and be approved before you can query it.OrbitalWiki vs N2YOA satellite tracking site with a small free API aimed at pass predictions: where a satellite is now, and when it next flies over you.OrbitalWiki vs Heavens-AboveA long-standing astronomy and pass-prediction site for observers. Excellent sky charts, no public API and no bulk data.

Something is broken right now

Four things that stop a satellite-data pipeline, each with the explanation first and the fix second. Every claim about another service links to that service’s own documentation.

Where this catalog is weaker

OrbitalWiki is a prototype, not an operational service. It does not compute conjunctions, it is not a source of record for orbital elements, and its status field is derived from upstream codes that do not always mean what the label suggests. For anything safety related, use the primary sources.

How each field is resolved, and how confident we are in it, is written up in the methodology.

Read the API docs