Compute resource limits
Last updated 2026-06-16
This guide details Fastly resource limits for Compute services. These limits change based on whether you're using a free account or have purchased one of our packaged offerings. 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 for additional details.
Port limits
By default, Compute services only accept client connections on port 443. To learn more about allowing client connections on port 80, contact your account manager or sales@fastly.com.
NOTE
By default, 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.
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 | 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 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 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 options are outlined below, but may differ if you've purchased a package offering or are using a product or feature trial. Some limits may be raised; contact your customer success manager for details.
Edge data storage naming restrictions
When naming a store, whether through the web interface or API, 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 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 customer success 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) | 250,000 per month | Paid accounts can raise this limit for an additional fee. | |
| Class B operations (reads) | 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 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. |
