--- header: Compute resource limits lang: en last_updated: '2026-06-04' url: https://docs.fastly.com/products/compute-resource-limits --- This guide details Fastly resource limits for [Compute](https://docs.fastly.com/products/compute) services. These limits change based on whether you're using a free account or have purchased one of our [packaged offerings](https://www.fastly.com/package-entitlements/). These limits may be further defined on your service order. > **NOTE:** In addition to the limits described here, Compute services can also be limited by the products or platform services that you access through your application code. Check out our [network services resource limits](https://docs.fastly.com/products/network-services-resource-limits) for additional details. ## Port limits Compute services accept client connections on port 443 only. This is different from VCL services, which support client connections on port 80. > **NOTE:** If your Compute service receives a request on port 80, Fastly automatically returns a 308 Permanent Redirect response status with the `Location` header indicating the HTTPS version of the same URL in a `Location` header. ## Default limits Item | Limit | Scope -----|-------|------ Maximum compiled package size | 100MB | per service Maximum cached object size | 100MB | per object Maximum CPU time available to a single request instance | 50ms | per execution Maximum runtime for a single request instance | 2 min (60s for trial accounts) | per execution Maximum memory consumption | 1M bytes stack, 128MB heap | per execution Maximum number of dictionary lookups | 32 | per execution Maximum number of backend requests | 32 (10 for trial accounts) | per execution Maximum number of dynamic backends | 200 | per service [Vary rules](https://www.fastly.com/documentation/guides/concepts/edge-state/cache/#limitations-and-constraints) | 8 | per cache object Maximum length of a request header | 128KB | per header Maximum length of a response header | 128KB | per header Maximum length of a method name | 8192 bytes | per request Maximum length of a URL | 8192 bytes | per request An *execution* refers to a single instance of a Compute program being executed, normally in response to a client HTTP request. Separate limits also apply to the use of [log tailing](https://www.fastly.com/documentation/guides/integrations/streaming-logs/setting-up-remote-log-streaming-for-compute) with Compute services. ## Service chain limits Item | Limit | Implications -----|-------|------------- Service chains and hops | 20 hops, 6 unique services | Read our [developer information about loop detection](https://www.fastly.com/documentation/guides/concepts/service-chaining/#loop-detection) for more info. ## Edge data storage limitations When working with edge data stores, there is a limit of 100 shared resources total per account (Config Store, KV Store, Secret Store, and ACLs on Compute combined). Limits for each of our [edge data storage](https://docs.fastly.com/products/edge-data-storage) options are outlined below, but may differ if you've purchased a [package offering](https://www.fastly.com/package-entitlements/) or are using a [product or feature trial](https://www.fastly.com/documentation/guides/account-info/billing/account-types). Some limits may be raised; contact your account manager for details. ### Edge data storage naming restrictions When naming a store, whether through the [web interface](https://www.fastly.com/documentation/guides/compute/edge-data-storage/) or [API](https://www.fastly.com/documentation/reference/api/services/resources/), be aware of the following restrictions: - Store names must be unique. - Store names must begin with an ASCII alphabetical character and contain only ASCII alphanumeric and underscore characters. - Store names cannot be an empty string. ### Config Store Config Store is included with your Compute service with the following limitations: Item | Limit | Implications -----|-------------|--------------------|------------- Config stores | 5 | Paid accounts can purchase additional stores for a monthly fee. Config store entries (per store) | 500 | An error informs you that you've exceeded the limit. Config store key length | 255 characters | An error informs you that you've exceeded the limit. Config store value length | 8,000 characters | An error informs you that you've exceeded the limit. Config store write operations | 1000 writes per hour | Write limits are shared with all other Fastly API calls. Exceeding the limit will result in an API limit error. Refer to [API rate limiting](https://www.fastly.com/documentation/reference/api/#rate-limiting) for more info. ### KV Store KV Store is included with your Compute service with the following limitations: Item | Limit | Implications -----|-------------|--------------------|------------- KV stores | 5 | Paid accounts can purchase additional stores for a monthly fee. File size limit | 25 MB | This limit can be raised to as much as 100 MB upon request. Contact your account manager or sales@fastly.com for more information. Metadata storage | 2000 bytes | Must be composed of Unicode characters encoded using UTF-8. [Class A operations (writes)](https://docs.fastly.com/products/edge-data-storage#billing-1) | 250,000 per month | Paid accounts can raise this limit for an additional fee. [Class B operations (reads)](https://docs.fastly.com/products/edge-data-storage#billing-1) | 5 million per month | Paid accounts can raise this limit for an additional fee. Writes per second (per store) | 1000 | This is a soft limit for the durable store and it auto-scales as needed. Reads per second (per store) | 5000 | This is a soft limit for the durable store and it auto-scales as needed. Rate limit | 1 write per second per item | An error informs you that you've exceeded the limit. Batch requests | 100,000 items per request | Exceeding this limit will result in long execution time before eventual failure. #### Key limitations - Keys cannot start with `.well-known/acme-challenge/`, `.`, or `..`. - Key names can contain any sequence of valid Unicode characters of length 1-1024 bytes when UTF-8 encoded. The following characters can be used in key names but can't be searched in a prefix query string: `!`, `"`, `$`, `%`, `&`, `(`, `)`, `*`, `+`, `,`, `/`, `\`, `:`, `<`, `=`, `>`, `@`, `[`, `]`, `` ` ``, `{`, `}`. - Keys cannot use [Unicode characters](https://www.w3schools.com/charsets/ref_html_utf8.asp) 0 through 32, 65534, and 65535 as single-character key names. - The following characters cannot be used in key names: - `#`, `;`, `?`, `^`, and `|` - line feed (LF) characters - carriage-return (CR) characters ### Secret Store Secret Store is included with your Compute service with the following limitations: Item | Limit | Implications -----|-------------|--------------------|------------- Secrets (total across all stores) | 10 | Paid accounts can purchase additional secrets for a monthly fee. Maximum secret size | 64 KB | An error informs you that you've exceeded the limit. Rate operations | 5 reads per Compute request | An error informs you that you've exceeded the limit.