Intercept API: Debug localhost. Share it anywhere.

Why Intercept API

Secrets redacted

Authorization and cookie headers, API keys, tokens and passwords in URLs and request bodies are replaced with [REDACTED] before your history is saved.

Works with any stack

It captures traffic at the browser's network layer, so Express, Django, Rails, Spring Boot, Next.js or FastAPI work as they are, with no code changes.

AI explains errors

Ask Gemini, OpenAI, Anthropic or a local model to explain a failing call, using your own API key. The key stays in your browser.

How Intercept API works

Three steps to full visibility into your localhost traffic.

1. Install the extension. Add the lightweight Manifest V3 extension from the Chrome Web Store. It captures your localhost traffic, and other sites only if you add them.
2. Intercept requests. HTTP requests to localhost are captured automatically, with method, URL, headers and body, and streamed to the live dashboard.
3. Share via tunnel. Start a secure tunnel with one click. Share the link and secret with teammates or testers so they can reach your local server from anywhere.

Everything you need to debug localhost APIs

A complete debugging toolkit for developers who work on localhost.

Instant replay

Re-fire a localhost request captured in the last 5 minutes with a single click. Compare responses, test idempotency and chase intermittent bugs without leaving the dashboard.

Mock rules

Match requests by URL pattern and return the status code, headers and JSON body you choose.

Tunnel sharing

Share your localhost through a secure, secret-protected tunnel link. No port forwarding, no ngrok, no configuration.

Request interception

Fetch, XHR and API calls to localhost are logged with their method, URL, headers and body.

Real-time dashboard

Live streaming with instant search, method and status filters, and JSON highlighting.

Chrome extension

A Manifest V3 extension with a built-in mini-dashboard: turn interception on or off, see the connection status, open the full dashboard.

Chrome extension capabilities

Everything the Chrome extension can do, step by step.

Getting started

Install the extension once and connect it to your account.

1. Install the extension. Add Intercept API from the Chrome Web Store. It connects to your account automatically, with no setup.
2. Sign in. Open the extension popup and sign in with your account. It links the extension to your dashboard, so there are no URLs or API keys to paste.
3. Check the connection. Click the Intercept API icon in your browser toolbar. The popup shows a green Connected status.

For hosts

You run the app on localhost and want someone else to reach it.

1. Open the tunnel panel. In the dashboard, choose Tunnel in the sidebar. This opens tunnel management.
2. Start the tunnel. Click Start tunnel. The extension opens a secure WebSocket channel and generates a unique tunnel URL and secret.
3. Share the link and secret. Copy the tunnel link and secret and send them to teammates or testers. Requests they send through it are forwarded to your localhost.

For consumers

Someone shared a tunnel link and secret with you and you want to use their app.

1. Receive the link and secret. The host sends you a tunnel link, a standard HTTP URL on the Intercept API backend, and a secret.
2. Send requests. Open the link in your browser and enter the secret, or call it from code with POST /api/tunnel/forward. Every request is forwarded to the host's localhost.
3. Get real responses. Responses come back from the host's local server in real time. You need no special software or configuration.

Frequently asked questions

How do I debug localhost API requests without Postman or DevTools?

Install the Intercept API Chrome extension and it automatically captures the HTTP requests your browser sends to localhost — method, URL, headers, and body — and streams them to a live dashboard where you can inspect, replay, and mock them.

How do I share my localhost app with a teammate?

Click Start Tunnel and Intercept API opens a secure WebSocket channel through its servers and gives you a tunnel link and a secret. Anyone you send both to can open your local app in their browser, or call it from code with POST /api/tunnel/forward. No port forwarding required.

Does Intercept API send my requests to a server?

Yes. The extension sends each captured request over an encrypted connection to the Intercept API server so your dashboard can show it. Before anything is saved to your history, secrets are replaced with [REDACTED]: Authorization and cookie headers, API keys, tokens and passwords in URLs and request bodies. Your history keeps your latest 1,000 requests and is deleted 24 hours after your last capture. A full copy (bodies up to 512 KB) is kept for 5 minutes after capture or after its last replay, so Replay can resend the exact request.

Is Intercept API free?

Yes. Intercept API is free: install the Chrome extension, create an account and start capturing requests. There's no paid plan and no credit card required.

How do I replay or mock an API response while developing?

Select a localhost request captured in the last 5 minutes and click Replay — the extension re-sends it from your browser with the same headers and body. Or create a mock rule that matches a URL pattern and returns your own status code, headers and JSON body. Neither touches your application code.

Does Intercept API work with any backend framework?

Yes. It intercepts traffic at the browser network layer using Chrome's webRequest API, so it works with any server on http://localhost or 127.0.0.1 — Express, Django, Rails, Spring Boot, Next.js, FastAPI, and more.

Ready to debug smarter?

Set up Intercept API in under a minute. It's free, and no credit card is required.

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