> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gladeapi.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Data Freshness and Caching

> Understand Glade API cache targets and response headers that identify cache status and source-data freshness.

Glade API caches normalized operation results. A request can therefore return cached data instead of making a new provider request. Cache hits and provider-backed results have the same response schema and each successful operation costs one unit.

## Cache targets

| Operation | Cache target |
| - | -: |
| Product details, sales estimates, seller profiles | 6 hours |
| ASIN/GTIN conversion | 30 days |
| Product variants | 12 hours |
| Stock estimates, product search, best sellers | 15 minutes |
| Product offers and deals | 5 minutes |
| Product reviews and autocomplete | 1 hour |
| Category products | 30 minutes |
| Category taxonomies and author profiles | 24 hours |

These are cache targets, not freshness guarantees. When a provider is temporarily unavailable, Glade API may serve a previously cached result rather than fail the request.

## Response headers

Use these headers to inspect the result:

| Header | Meaning |
| - | - |
| `X-Glade-Cache` | `hit`, `miss`, or `stale` |
| `X-Glade-Data-Fetched-At` | ISO 8601 upstream-result creation time, or Glade API retrieval time when the upstream value is absent |
| `X-Glade-Schema-Version` | Version of the normalized response contract |
| `X-Glade-Usage-Units` | Units charged for this HTTP exchange |

For monitoring workflows, compare `X-Glade-Data-Fetched-At` rather than assuming that every request represents a new provider fetch.

`X-Glade-Data-Fetched-At` is retrieval metadata. It is not necessarily the
time when Amazon first observed, published, or changed the underlying value.
Operations that calculate a derived value can return a separate estimation
time and explicitly state whether a source-observation timestamp is available.


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