Compute resource limits

This guide details Fastly resource limits for Compute services. These limits change based on whether or not you've purchased one of our packaged offerings or you're using a trial account.


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 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.


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

Limits marked with an asterisk (*) can be adjusted in code using the limits interface in your preferred software developer kit (SDK). Contact support to discuss raising any other limits.

Maximum compiled package size100MBper service
Maximum cached object size100MBper object
Maximum CPU time available to a single request instance50msper execution
Maximum runtime for a single request instance2 min (60s for trial accounts)per execution
Maximum memory consumption1M bytes stack, 128MB heapper execution
Maximum number of dictionary lookups16per execution
Maximum number of backend requests32 (10 for trial accounts)per execution
Vary rules8per cache object
Maximum length of a header name8192 bytes*per header
Maximum length of a header value8192 bytes*per header
Maximum length of a method name8192 bytes*per request
Maximum length of a URL8192 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 with Compute services.

Service chain limits

Service chains and hops20 hops, 6 unique servicesRead our developer information about loop detection for more info.

Edge data storage limits

Limits for each of our edge data storage options differ if you've purchased a package offering or are using a product or feature trial.

Config Store

Config Store is included with your Compute service with the following limitations.

ItemTrial limitPaid account limitImplications
Config stores15Paid accounts can purchase additional stores for a monthly fee.
Config store entries (per store)100500An error informs you that you've exceeded the limit.
Config store key length255 characters255 charactersAn error informs you that you've exceeded the limit.
Config store value length8,000 characters8,000 charactersAn error informs you that you've exceeded the limit.
Config store write operations100 writes per hour100 writes per hourWrite limits are shared with all other Fastly API calls. Exceeding the limit will result in an API limit error. Refer to API rate limiting for more info.

KV Store

KV Store is an add-on and is priced in addition to Compute services. The following limitations apply:

  • The number of KV stores you can create is limited to your account’s available resources allotment.
  • KV store names have a maximum length of 255 bytes in UTF-8 format.
  • KV stores have a rate limit of 1,000 writes per second per store, and 5,000 reads per second per store.
  • KV store items support a maximum key length of 1024 bytes in UTF-8 format.
  • KV store items have a rate limit of 1 write per second.
  • KV store item batch requests have a limit of 100,000 items per request.
  • KV stores support values submitted using any file type and have a maximum size of 25MB. This maximum can be raised to 100MB upon request. Contact your account manager or for more information.
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