Questions worth answering before you start.
Including the limits, and the ones where the answer is no.
Which protocols are supported?
HTTP, WebSocket and raw TCP. HTTP and WebSocket endpoints get a subdomain; raw TCP gets a dedicated relay port. The free plan covers HTTP; WebSocket and raw TCP are part of the paid plans.
Can I try it without creating an account?
Yes. Guest mode provisions a default webhook endpoint immediately, with no account and no card: 1,000 requests per month, 50 stored requests and 2 concurrent sessions.
What does the free plan include?
After registering: one HTTP endpoint of your own, 10,000 requests per month, 100 stored requests, 5 request rewrites and 8 concurrent sessions. Each of those is enforced in code, and when a monthly limit is reached the relay answers 429 rather than dropping traffic quietly.
Can I pay for a plan today?
Yes. Open /pricing to see Free, Solo, and Team with country-localized Paddle prices. Workspace owners can subscribe via a one-page checkout overlay; the free plan stays available without paying.
Which platforms can run the agent?
The macOS desktop app runs the agent for all three protocols, as a DMG for Apple Silicon and Intel. The browser console can receive HTTP traffic in log mode without installing anything.
How is access controlled?
Console routes require an authenticated session, the agent authenticates with a token you can rotate, and any endpoint can be marked private with an IP or CIDR allow list.
Where are request logs stored, and for how long?
On Mercur infrastructure, not on your machine, for 30 days. Bodies are truncated to a 256 KB preview and headers to 32 KB. An endpoint only records logs when it runs in a log mode, so proxy-only endpoints store nothing.
What happens when my agent disconnects?
The endpoint stops serving within about 15 seconds and returns 503 until the agent reconnects. Requests that arrive during that window are not queued or replayed.
Plan details: Pricing · Guides: Docs · Start without an account: Webhook tester