# CID Lookup API

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Support for these endpoints is currently in progress.
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You can look up CIDs for individual slots or transactions by using our hosted service:

* **Transaction signatures**: **`https://cid.old-faithful.net/api/v1/sig-to-cid/<sig>`**
* **Blocks**: **`https://cid.old-faithful.net/api/v1/slot-to-cid/<slot>`**

If the CID is available, the API will return the CID for the block or transaction.

A HTTP 404 response indicates the transaction or slot is unavailable in Old Faithful.