---
title: "Edge Cache"
oldUrl:
  - /deploy/classic/edge-cache/
---

:::info Legacy Documentation

You are viewing legacy documentation for Deno Deploy Classic. We recommend
migrating to the new
<a href="/deploy/">Deno Deploy</a> platform.

:::

The [Web Cache API](https://developer.mozilla.org/en-US/docs/Web/API/Cache) is
supported on Deno Deploy. The cache is designed to provide microsecond-level
read latency, multi-GB/s write throughput and unbounded storage, with the
tradeoff of best-effort consistency and durability.

```ts
const cache = await caches.open("my-cache");

Deno.serve(async (req) => {
  const cached = await cache.match(req);
  if (cached) {
    return cached;
  }

  const res = new Response("cached at " + new Date().toISOString());
  await cache.put(req, res.clone());
  return res;
});
```

Cached data is stored in the same Deno Deploy Classic region that runs your
code. Usually your isolate observes read-after-write (RAW) and write-after-write
(WAW) consistency within the same region; however, in rare cases recent writes
can be lost, out-of-order or temporarily invisible.

## Expiration

By default, cached data is persisted for an indefinite period of time. While we
periodically scan and delete inactive objects, an object is usually kept in
cache for at least 30 days.

Edge Cache understands standard HTTP response headers `Expires` and
`Cache-Control`. You can use them to specify an expiration time for every cached
object, for example:

```
Expires: Thu, 22 Aug 2024 01:22:31 GMT
```

or:

```
Cache-Control: max-age=86400
```

## Limitations

- If a response is not constructed from a `Uint8Array` or `string` body, the
  `Content-Length` header needs to be manually set.
- Deletion is not yet supported.