Vercel Sandbox Firewall Request Proxying and Filtering Is Here
The Vercel Sandbox firewall now supports forwarding specific HTTP requests to a proxy you control. You can also use matchers to filter forwarding and credentials brokering to only the requests that need it. It’s a meaningful upgrade for developers building AI-powered applications on Vercel.
Until now, controlling outbound sandbox traffic required custom middleware or external tooling. That’s no longer the case. You can now route outbound sandbox traffic through your own proxy for logging, debugging, or transforming requests and responses. Set a forwardURL on any allowed domain, and the firewall will forward matching HTTPS requests to your server.
Vercel also built identification into the flow. Each proxied request carries additional headers so the receiving server knows exactly where the traffic originates, including the original SNI, scheme, port, and a Vercel-issued OIDC token. That token lets the proxy authenticate the request and identify the source team, project, and sandbox.
Beyond routing, precision filtering is now part of the picture. Matchers let developers filter request forwarding or credentials brokering to requests matching a specific path, method, query string, or headers. This gives fine-grained control over which requests get transformed, for example, only forwarding POST requests to a specific API path while allowing all other traffic through untouched.
Together, these features close a real gap. As AI agents make more autonomous network calls, teams need visibility and control over exactly what goes out and what comes back. Vercel Sandbox firewall’s request proxying and filtering delivers that control without adding infrastructure complexity.
