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Small, fast developer tools.

Free, no sign-up. Everything runs in your browser, so your data never leaves it.

Free developer tools for APIs, webhooks and MCP servers

Toolbench is a small set of free developer tools for the unglamorous parts of API work: checking what a webhook actually sent, why its signature doesn't match, and whether an API spec is valid before anything is built on it. They run in your browser, with no account and nothing to install.

They're also made for building on top of AI agents and MCP (Model Context Protocol) servers. The webhook tester captures the real payloads that trigger an agent and checks signatures before anything reaches the model. The OpenAPI validator catches broken references, missing parameters and duplicate operationIds before a spec becomes an MCP server's tools.

Questions

Are these developer tools free?

Yes. Every tool is free with no account and no sign-up. Open a page and start using it.

Is my data sent to a server?

Mostly no. Validation, signature checks and signing run in your browser. The exceptions are the webhook inbox, which stores the requests sent to your URL for 7 days, and features that must reach another server, such as sending a test webhook or loading a spec from a URL. The privacy page has the details.

Can I use them when building MCP servers or AI agents?

Yes, that's what they're built around. Validate an OpenAPI spec before turning it into an MCP server's tools, capture the real webhook payloads that trigger an agent, and verify their signatures before anything reaches the model.

Can I suggest a tool?

Please do. Email ankursainiwork@gmail.com with the tool you wish existed.