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

# Functions limits

> Reference for Browserbase Functions regions, timeouts, build size, parameters, storage, and language support.

## Runtime limits

| Constraint | Limit |
| - | - |
| Region | `us-west-2` |
| Invocation timeout | 60 to 900 seconds |
| Default invocation timeout | 900 seconds |
| Language | TypeScript |
| Persistent storage | None |

Browserbase closes the browser session when the invocation reaches a terminal state. Functions don't support `keepAlive`.

## Build limits

| Constraint | Limit |
| - | - |
| Build upload | 25 MB |
| Functions per build | 10 by default |
| Lockfile | Required in the Function project directory |

A build over 25 MB returns HTTP `413`.

The Functions-per-build limit can vary by project. If a build needs more than its configured limit, contact [Browserbase support](mailto:support@browserbase.com).

## Request limits

| Constraint | Limit |
| - | - |
| Serialized `params` object | 64 KB |
| `timeout` | Integer from 60 through 900 seconds |

The invoke API returns `400 Bad Request` when the serialized `params` object exceeds 64 KB.

## Filesystem behavior

Don't rely on files remaining available between invocations.

Sandbox directories such as `/tmp` aren't guaranteed to be empty or unique for each invocation. Don't write credentials, tokens, or end-user data to shared temporary paths when your workload requires isolation.

## Unsupported session settings

Functions accept most [session creation options](/reference/api/create-a-session) through `sessionConfig` and `sessionCreateParams`.

Browserbase resolves the project from the API key. Don't pass `projectId`.

You can't set these fields:

* `keepAlive`
* `region`
* `playground`
* `scheduleMode`
* `solverServices`

<CardGroup cols={2}>
  <Card title="Write a Function" icon="code" href="/platform/functions/write">
    Configure defaults and validate Function parameters.
  </Card>

  <Card title="Invoke a Function" icon="terminal" href="/platform/functions/invoke">
    Override supported session settings for one invocation.
  </Card>
</CardGroup>


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