Catch a payload — or debug the handler on localhost
webhook.site is the classic instant bin for raw requests, and its CLI can forward them onward. Mercur starts from a guest URL too, adds a no-account tunnel in one npx command, and keeps going into Endpoints with full request history.
Choose Mercur when you need the payload and a path to run your real local handler (or pull history into an IDE agent).
Choose webhook.site when you only need to glance at a raw delivery as fast as possible with zero product lock-in.
How the jobs compare
| Job | Mercur | webhook.site |
|---|---|---|
| Instant URL, no account | Guest inspector in the browser, or a CLI tunnel | Category leader for instant bins |
| Inspect in the browser | Console request log | Browser inspect |
| Forward to localhost | npx CLI, no account; Endpoint when you register | CLI forward (whcli); not the default inspect-bin path |
| Persistent free endpoint | Free registered HTTP tunnel | Permanent URLs typically paid |
| Multi-protocol | HTTP / WS / TCP (WS/TCP paid) | HTTP |
| IDE / agent inspect (MCP) | Hosted Remote MCP over OAuth (Solo / Team) | No first-party webhook-inspect MCP documented |
| Inbound email testing | Workspace mailbox on Solo / Team, forwards JSON to an endpoint | Email address per token, no account needed |
Last verified: 3 September 2026. Competitor details change — verify on each vendor’s site.
Where Mercur is stronger
- Same zero-signup start, then a clear upgrade to localhost forward via the Mercur agent
- Signing up keeps the guest URL and its request log instead of starting over
- WebSocket and TCP on paid plans
- Hosted Remote MCP and team seats on higher plans
- Mail can forward into a local handler as JSON, not just sit in a browser view
When webhook.site wins
- Maximum brand familiarity for “just show me the JSON”
- Email address and DNS hostname per token without an account
- Broader automation / custom-action surface on paid tiers
- CLI forward without adopting a Mercur Endpoint
- No agent install when all you need is a bin
Common questions
Is Mercur a webhook.site alternative?
Yes for catching and inspecting webhooks. Mercur also covers the next step — forwarding to localhost and debugging the real handler.
Can webhook.site forward to localhost?
Yes, via the official Webhook.site CLI (`whcli forward`), and vendor docs say free users can omit the API key. It is an extra install and you bring a token id from the browser, but it is not a paid-only path. Mercur’s npm CLI covers the same job with `npx @mercur_dev/cli http 3000`.
Does a Mercur guest URL forward to my laptop?
It depends which guest surface you started from. The browser webhook inspector is log-only: it records the request and answers 204, so nothing reaches your machine. The npm CLI opens a guest tunnel in proxy mode, which does forward to the port you pass — no account required.
How long does a guest URL last?
Guest endpoints are ephemeral with a 24-hour TTL and request caps documented on Pricing and FAQ. If you register from the inspector, that endpoint and its stored requests move into your new workspace and the guest lease is dropped.
Which one tests inbound email?
Both, differently. webhook.site gives every token a matching …@emailhook.site address with no account. Mercur temporary mailboxes are a paid workspace feature (Solo and Team): a receive-only @mercur-mail.com address that can forward each message to one of your HTTP endpoints as JSON and is readable over MCP.
Who can see a Mercur payload?
Workspace members, plus anyone you hand a share link to. Share links are opt-in, expire after 24 hours, and can be revoked. Treat the contents like traffic logs — they are not redacted.
Related pages
Mercur vs ngrok
Mature localhost tunnel with a CLI, Traffic Inspector, replay, and an auto-assigned free-plan domain.
Read comparison →Mercur vs Hookdeck
Webhook event gateway with ingest, filtering, replay, and CLI MCP — oriented beyond local debug.
Read comparison →Mercur vs Hooklistener
Webhook URL + inspect product aimed at no-CLI, no-signup debugging (vendor-documented).
Read comparison →Mercur vs Cloudflare Tunnel
Mature edge tunnel with your Cloudflare account and domain — not a webhook console.
Read comparison →Try Mercur on a real webhook
Get a public HTTPS URL and inspect the payload in the browser, or run npx @mercur_dev/cli http 3000 to forward it to localhost without an account. Register when you want a stable endpoint.