ISS Location API (Open Notify) · Rate Limits

Iss Api Rate Limits

The Open Notify ISS API does not publish formal rate limit thresholds. The service is unauthenticated and free. No Retry-After, X-RateLimit-*, or RateLimit-Policy headers are documented. Best practice is to poll the location endpoint no more frequently than once every five seconds (the server-side refresh interval) and to cache responses client-side to reduce unnecessary load on the community-operated infrastructure.

Iss Api Rate Limits is the machine-readable rate-limit profile for ISS Location API (Open Notify) on the APIs.io network, conforming to the API Commons Rate Limits specification.

It captures 2 rate-limit definitions, across the free tier, measuring requests_per_second and requests_per_minute.

The profile also includes 3 backoff/retry policies defined and response codes documented for throttled, quotaExceeded, and serviceUnavailable.

Tagged areas include Space, ISS, Public API, Open Source, and Rate Limiting.

2 Limits Throttle: 429
SpaceISSPublic APIOpen SourceRate Limiting

Limits

ISS Location Polling Cadence ip
requests_per_second · second
1
The ISS position data updates approximately every five seconds on the server. Polling more frequently than once per second provides no additional precision and increases load on the shared service.
People in Space Polling Cadence ip
requests_per_minute · minute
12
Crew roster data changes rarely (crew rotations happen every few months). Polling more than a few times per hour is unnecessary for most use cases.

Policies

Fair Use
The service is community-operated and funded voluntarily. Callers should implement client-side caching, avoid tight polling loops, and be good citizens of a shared public resource.
Backoff Strategy
If the server returns a 429 or 503, implement exponential backoff before retrying. No Retry-After header is documented, so begin with a 5-second wait and double on each subsequent failure.
Caching
Cache ISS position responses for at least five seconds (the server refresh interval) and astronaut roster responses for at least one hour to minimize unnecessary traffic.