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HTTP Headers

Quotas and limits

See our page on API Quotas & Limits for information regarding these headers.

Unstable operations

Because we aggregate data from different sources, there are many moving parts in the API, and reproducibility is a challenge. Our default strategy is to ingest the entire datasets into Cobaltmetrics, so that we control when and how data gets updated.

Some operations, however, interact with third-party services and thus cannot be guaranteed to return the same results over time. Caching results is not always an option, as we would risk returning stale data. We refer to these operations as unstable operations.

All unstable operations are disabled by default and need to be explicitely enabled by using the X-Release HTTP header in the requests you send to the API:

  • X-Release: stable: this is the default setting, whereby unstable operations are disabled;
  • X-Release: unstable: this is the setting whereby all operations are enabled, stable operations and unstable operations alike.

The following unstable operations are currently available in the API:

  • HTTP link header interpolation, see the page on URI transmutation for more information.

Note that unstable operations are currently unavailble in the web application. They can only be enabled via API requests.