# Transform rules are now available in vercel\.json

**Published:** July 22, 2025 | **Authors:** Charlie Meyer

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You can now define transform rules in [`vercel.json`](https://vercel.com/docs/project-configuration) to modify HTTP request and response headers or query parameters, without changing application code.

Unlimited transform rules are available for all customers, and let you:

- Set, append, or delete request headers, response headers, and query parameters
- Use conditional logic to apply changes based on request metadata
- Match by equality, inequality, prefixes, suffixes, inclusion in string arrays, or numeric comparisons for fine-grained control

[Video: Transform Rules Playground demo video light](//videos.ctfassets.net/e5382hct74si/3jCGaudBi8lxa3vP63YFEn/2e751a6e52ef2238549d8bc6770e8613/transforms_demo.mp4)

*Explore the [ interactive transform rules playground](https://transforms-demo.vercel.app/) to see how this feature works.*

This expands the flexibility of Vercel's CDN, which already supports routing behavior like redirects and rewrites to external origins.

For example:

**vercel.json**
```json
{
  "$schema": "https://openapi.vercel.sh/vercel.json",
  "routes": [
    {
      "src": "/(.*)",
      "dest": "https://my-secure-proxied-dashboard.com/$1"
      "transforms": [
        {
          "type": "request.headers",
          "op": "set",
          "target": {
            "key": "x-using-vercel-cdn"
          },
          "args": "secret-value"
        }
      ]
    }
  ]
}
```

Refer to the [transform rules documentation](https://vercel.com/docs/project-configuration#transform-object-definition) for detailed examples.

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📚 **More updates:** [View all changelog entries](/changelog/sitemap.md) | [Blog](/blog/sitemap.md)