GENERAL HOOK

WHAT IS GENERAL HOOK?

General Hook runs a real Node.js server directly in your browser using WebAssembly. No installs, no cloud accounts, no ports to forward. Click RUN and you get a live public URL in seconds — share it, test against it, paste it into webhook settings.

Use it when you need to:

Mock an API your frontend talks to before the backend is built
Test webhook integrations without deploying anything
Prototype API shapes and generate an OpenAPI spec to hand off
Replay and inspect real traffic captured from a browser session

BUILDER TAB

Define routes manually. Each route needs an HTTP method, a path, and a status code. The response body defaults to an empty object — click Edit body to set the exact JSON that endpoint will return.

Adding a route

Click + ADD and fill in the method, path (must start with /), and status
Click ADD to save it to the list
Click Edit body on any row to open the JSON editor
Click ✕ to remove a route

Tips

Status 201 is conventional for POST routes that create resources
Status 204 means no response body (the server will still send one, but clients ignore it)
You can add multiple routes to the same path with different methods

UPLOAD TAB

Got an existing spec or export? Drop it in. General Hook detects the format automatically and extracts all routes — no manual entry needed.

Format Reference

FORMAT	EXTENSIONS	NOTES
OpenAPI 3.x	.yaml, .yml, .json	Extracts first 2xx response per operation. Uses `example` fields or `x-mock-response` for bodies.
Swagger 2.0	.json, .yaml	Respects `basePath`. Extracts response examples from the `examples` key or `schema.example`.
Postman Collection	.json	Supports v2.x collections including nested folders. Uses the first saved response example for the body and status.
Insomnia Export	.json	Supports v4 exports. Extracts method and path from each request resource. Bodies default to empty.
HAR	.har, .json	Captures real browser traffic. Deduplicates by method + path (first occurrence wins). Only JSON responses are used as bodies.
routes.json	.json	A plain JSON array of `{ method, path, status, body }` objects. Simplest format for hand-crafted mocks.
Server file	.js	A raw Express server file. Runs as-is inside the pod. Must listen on port 3000.

Test files

Sample files for every format are available in /test-files/ on the dev server. Download them to test the upload flow end-to-end.

openapi3.yaml — OpenAPI 3.0.3 Petstore
swagger2.json — Swagger 2.0 Bookstore
postman.json — Postman Collection v2.1
insomnia.json — Insomnia Export v4
capture.har — HAR capture (Shop API)
routes.json — Raw routes array

GEN SPEC TAB

Build an OpenAPI 3.0 YAML specification from scratch. The preview updates live as you add endpoints and edit bodies. Use this to produce a spec you can hand off to your team, import into Postman, or feed to code generators.

Workflow

Set your API title and version at the top
Add endpoints the same way as the Builder tab — method, path, status, optional summary
Click Edit body on any endpoint to set the example response JSON
The YAML preview on the right updates immediately
Click COPY to copy the YAML to your clipboard
Click DOWNLOAD to save it as openapi.yaml

Running the spec

Clicking RUN while on the Gen Spec tab boots a mock server using the spec's routes. Equivalent to building in the Builder tab then running — just with the extra YAML output.

WEBHOOKS TAB

Boots a dedicated webhook receiver — a server that captures every incoming HTTP request and logs it to a live dashboard. No routes to configure, no JSON to write.

How to use it

Switch to the Webhooks tab and click RUN
Copy the public URL from the portal card
Paste it into the webhook settings of any service (GitHub, Stripe, Slack, etc.)
Open the URL in a browser to see the live request dashboard
Every request appears in real time — method, path, headers, body

Example: GitHub webhook

1. Go to your repo → Settings → Webhooks → Add webhook
2. Paste the General Hook URL into "Payload URL"
3. Set Content type to application/json
4. Choose which events to send
5. Click Add webhook — GitHub will send a ping immediately
6. Open the dashboard URL to see the ping payload

HOW IT WORKS

General Hook uses BrowserPod — a WebAssembly runtime that runs Node.js 22 directly in your browser tab. When you click RUN:

A Node.js environment boots inside your browser (via CheerpOS/WASM)
Your routes or server file are written into the pod's virtual filesystem
npm install runs inside the pod to fetch Express
The Express server starts on port 3000 inside the pod
BrowserPod tunnels that port to a public URL via its portal system

Nothing runs on an external server. The Node.js process lives inside your browser tab. Closing the tab stops the server.