What each tool is

ngrok is a tunnelling service. An agent on your machine gives a local port a public URL, and its local web interface lets you inspect and replay the requests that arrive through that tunnel.
Intercept API is a Chrome extension and web dashboard for debugging the API calls your own browser makes to localhost. It also has a tunnel, so you can share your local server.

Feature comparison

Feature	Intercept API	ngrok
Public URL for a local server	Yes: HTTP, protected by a tunnel secret; started from the dashboard or the extension	Yes: HTTP, TCP and TLS endpoints
Captures the requests your browser sends to localhost	Yes, automatically	No: only traffic that arrives through the tunnel
Inspect requests	Yes: method, URL, headers and body in a live dashboard	Yes: tunnel traffic in the agent's web interface
Replay a request	Yes: localhost requests captured in the last 5 minutes	Yes: tunnel requests, from the web interface
Mock API responses	Yes: URL-pattern rules return your status code, headers and JSON body	Partly: traffic policy rules can return a fixed response for tunnel traffic
Console logs next to the traffic	Yes	No
AI explains errors and API calls in plain language	Yes, with your own Gemini, OpenAI, Anthropic or local-model key	No
Custom domains	No	Yes
Install	Chrome extension, then sign in	Command-line agent, then sign in with an authtoken
Price	Free	Free plan with limits, and paid plans

When to choose ngrok

You need to receive webhooks: a webhook provider can't enter an Intercept API tunnel secret.
You need a public URL for something other than HTTP, such as a TCP or TLS service.
You want a custom domain, or a tunnel that stays up for a long-running service.
You want features in front of your app such as traffic policies and authentication.
You don't need to see the requests your own browser makes.

When to choose Intercept API

You're building a frontend against a local API and want to see every call it makes, with headers and bodies, without opening DevTools.
You want to replay a failing request, or answer it with a mock response, without changing your code.
You want the page's console errors and an AI explanation next to the request that failed.
You sometimes need to share your local app with a teammate, without installing a command-line tool.

Using both

They do different jobs, so they work well together: ngrok for a stable public endpoint, and Intercept API to watch, replay and mock the calls your app makes while you develop.

Limits of the Intercept API tunnel

A tunnel closes after 2 hours without traffic or after 8 hours in total.
Each response through the tunnel can be up to 5 MB.
The tunnel runs through the Chrome extension, so Chrome must stay open and the extension signed in.

Sources

The ngrok details above are summarised from its public documentation and pricing page; check those for current plans and limits. Products change: if something here is out of date, email ismailabbasi118@gmail.com.