Comparison

Postbin Ultra sits in the gap between "cloud request bin" and "full HTTPS proxy." It is local-first, runs entirely on your machine with no accounts, captures any HTTP method on any port, and adds a forward + replay loop on top. Here's how it stacks up against the alternatives.

#TL;DR

#Postbin Ultra vs webhook.site

Webhook.site is the canonical "give me a public URL that prints requests" SaaS. It's good when you genuinely need a public URL — Stripe sandbox, GitHub webhooks pointed at the public internet — but every captured request goes through their cloud first. That's a privacy concern for anything sensitive, a latency hit, and you have to trust them not to dump your bins. Their replay feature also requires a paid plan for most realistic uses.

Postbin Ultra is what you want when:

• The webhook source can already reach your machine (local dev with mkcert, ngrok / Cloudflare Tunnel pointed at Postbin, vendor sandboxes that POST to http://your-laptop.local)
• You're inspecting traffic from your own client code (SDK debugging, smoke-testing your own integrations against staging)
• You don't want any captured payload to leave your machine
• You want collapsible JSON, syntax highlighting, and forward + replay without paying for it

You can run both: webhook.site to receive the public-internet hits, Postbin to record + forward / replay them locally.

#Postbin Ultra vs ngrok inspect

ngrok ships an inspect UI on http://localhost:4040 that shows requests passing through your tunnel. It's good — but tightly coupled to the tunnel. Postbin works whether you're tunneling, running entirely on localhost, or accepting LAN traffic, and isn't gated on an ngrok account.

ngrok also doesn't let you change the tunnel destination per-replay. Postbin does — capture once with Forward off, then point Forward at any URL and Replay to that destination as many times as you want.

Common workflow when both are useful:

Stripe → ngrok tunnel → http://localhost:9000 (Postbin) → http://localhost:3000 (your app)

ngrok handles "make my localhost reachable from the internet"; Postbin handles "show me what's happening + let me replay."

#Postbin Ultra vs RequestBin

RequestBin (the original, now part of Pipedream) is a cloud-only request bin. It's free for inspection, paid for replay / persistence. Same trade-offs as webhook.site.

The self-hostable open-source RequestBin is unmaintained and missing modern HTTP features (HTTP/2, multipart streaming) that Postbin handles.

#Postbin Ultra vs mitmproxy

mitmproxy is a serious tool — a full HTTPS man-in-the-middle proxy with scripting, content modification, certificate generation. If you need to intercept HTTPS traffic from a system you don't control (a browser, a mobile app), install mitmproxy's CA on the device and you can rewrite anything.

Postbin Ultra is much narrower. You point a client at Postbin's HTTP capture URL, Postbin records the request, optionally forwards it. There's no certificate generation, no in-flight rewriting, no scripting. The trade-off is zero setup — install, launch, paste the URL — and a UI optimised for "I want to read this request" rather than "I want to script the protocol."

If you need full HTTPS interception, use mitmproxy. If you want to inspect requests that you control the origin of, Postbin is significantly faster to get running.

#When to pick what

#Next

• Quick start — get Postbin running and capture your first request
• Forward + replay — the proxy + replay workflow that webhook.site and RequestBin can't do