# API Bundle Size Limit

Sets the maximum Webiny API Lambda bundle size and explains build errors.

- Repository: https://github.com/webiny/webiny-js (8051 stars)
- Category: DevOps
- License: see repository
- Last updated: 2026-10-30
- Runs scripts: no, instructions only

## Install

Claude Code: `npx skills add webiny/webiny-js --skill api-bundle-size-limit -g -a claude-code -y`
Codex: `npx skills add webiny/webiny-js --skill api-bundle-size-limit -g -a codex -y`
Cursor: `npx skills add webiny/webiny-js --skill api-bundle-size-limit -g -a cursor -y`
Gemini CLI: `npx skills add webiny/webiny-js --skill api-bundle-size-limit -g -a gemini-cli -y`

## Description

Covers how to configure the maximum allowed size of the Webiny API Lambda bundle using the Infra.Api.MaxBundleSize extension in webiny.config.tsx. Use when a project's API bundle exceeds the default 4.5 MB limit or when you want to enforce a stricter limit. Handles the extension syntax, byte calculations, and interpreting the build error message.

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# API Bundle Size Limit

## TL;DR

The `Infra.Api.MaxBundleSize` extension enforces a maximum size on the built API Lambda bundle. The default limit is 4.5 MB. If the bundle exceeds the limit the build fails with a clear error; add the extension to `webiny.config.tsx` to raise (or lower) it.

## Default Behavior

By default Webiny enforces a **4.5 MB** limit on the API Lambda bundle (`handler.mjs`). If the built output exceeds this, the build fails:

```
error   Build errors:
× asset size limit: The following asset(s) exceed the recommended size limit (4.5 MiB).
× entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (4.5 MiB).
error   build failed
```

## Raising the Limit

Add `Infra.Api.MaxBundleSize` to `webiny.config.tsx` with `size` in **bytes**:

```tsx
// webiny.config.tsx
import { Infra } from "webiny/extensions";

export const Extensions = () => (
  <>
    {/* Raise the API bundle size limit to 6 MB */}
    <Infra.Api.MaxBundleSize size={6 * 1024 * 1024} />
  </>
);
```

Common byte values:

| MB  | Bytes expression                | Exact bytes       |
| --- | ------------------------------- | ----------------- |
| 4.5 | `Math.round(4.5 * 1024 * 1024)` | 4718592 (default) |
| 5   | `5 * 1024 * 1024`               | 5242880           |
| 6   | `6 * 1024 * 1024`               | 6291456           |
| 8   | `8 * 1024 * 1024`               | 8388608           |
| 10  | `10 * 1024 * 1024`              | 10485760          |

## How It Works

The extension sets the `WEBINY_INFRA_API_MAX_BUNDLE_SIZE` environment variable (in bytes) which is read by the API bundler (`@webiny/build-tools`) at build time. The `WEBINY_INFRA_` prefix ensures the variable is **not** automatically forwarded to the Lambda function's runtime environment.

## Lowering the Limit

You can also enforce a stricter limit to catch bundle regressions early:

The rest: https://github.com/webiny/webiny-js/blob/HEAD/skills/user-skills/api-bundle-size-limit/SKILL.md