ngrok gets you a URL. Mercur shows you the traffic.
ngrok is the default localhost tunnel. Mercur is built for webhook debugging: guest inspect URLs, request history, manual retry, and Remote MCP for IDE agents — without fighting ngrok on every checklist row.
Choose Mercur when you need to see what a provider actually sent, retry a bad delivery, or pull request history into Cursor via Remote MCP.
Choose ngrok when you need a battle-tested CLI tunnel across platforms, broad protocol coverage, or an existing team already standardized on ngrok.
Who wins which job
| Job | Mercur | ngrok |
|---|---|---|
| Instant public URL for a webhook | Guest URL in seconds (inspect-only) | CLI tunnel after install + signup |
| See headers and body in the browser | First-class request log | Local inspector / mixed UX |
| Forward to localhost | macOS agent + Free tunnel | CLI on many platforms |
| Persistent free URL | Free registered HTTP endpoint | Free URLs typically rotate |
| IDE agent inspect (MCP) | Remote MCP on Solo / Team | Not a product focus |
| Linux / CI scripting | Not the strength today | Strong CLI + automation |
Summaries as of August 2026. Verify current limits on each vendor’s pricing page.
Where Mercur is stronger
- Guest webhook URL without creating an account first
- Request history with body preview on Mercur infrastructure
- Manual retry from the console after you fix the handler
- Remote MCP so an IDE agent can list tunnels and open payloads
- HTTP, WebSocket, and raw TCP through one macOS agent on paid plans
When ngrok wins
- Mature brand and docs that providers already mention
- CLI-first workflows on more than macOS
- Broad tunneling beyond webhook-shaped HTTP
- Enterprise trust and checklist breadth Mercur does not claim yet
Common questions
Is Mercur an ngrok alternative?
For webhook debugging and inspect-first endpoints, yes — that is the comparison this page is for. Mercur does not try to replace ngrok as a general network Swiss-army knife.
Does Mercur require a CLI?
No CLI is required to catch a payload on the guest webhook tester. Forwarding to localhost uses the macOS desktop agent after you register.
Can I keep a stable URL on the free plan?
Registered Free includes one HTTP Endpoint with a stable endpoint. Guest URLs are ephemeral (24-hour TTL) and inspect-only.
Does Mercur run on Windows or Linux?
The desktop agent is macOS today. Do not assume Windows or Linux agents exist until they are published on the product site.
Related pages
Mercur vs Hookdeck
Webhook event gateway with strong ingest, filtering, and replay — oriented beyond local debug.
Read comparison →Mercur vs webhook.site
Fastest way to catch a raw payload. Limited localhost forward on free/common workflows.
Read comparison →Mercur vs Hooklistener
Webhook URL + inspect product aimed at no-CLI, no-signup debugging.
Read comparison →Mercur vs Cloudflare Tunnel
Mature edge tunnel with your Cloudflare account/domain — weak webhook inspect UX.
Read comparison →Try Mercur on a real webhook
Get a public HTTPS URL, inspect the payload, then upgrade to a Endpoint when you are ready to hit localhost.