Webhook.co README
The full upstream README, mirrored here for reference. Install config, tool schemas, adoption signals, and an original overview live on the Webhook.co listing page.
webhook.co
A free, permanent, signed webhook URL you can inspect and replay to localhost — from the CLI, API, dashboard, or MCP.
webhook.co captures the webhooks other services send you, so you can see exactly what arrived,
check the signature, and replay it to your local dev server without redeploying. The same operations
run from the CLI, the REST API, the web dashboard, and an MCP server.
- Receive — a stable, signed URL on a dedicated apex (
https://wbhk.my/<token>). No expiring tunnels. - Inspect — every request, headers and body, with a clear signature result.
- Replay to localhost — forward any captured event to
http://localhost:3000with one command. - Deliver — send events on to your own destinations, in order, with retries.
Want to see it work first? Open webhook.co/play — send a webhook, watch it land. No signup, nothing to install.
Open source · Apache-2.0 · private by default.
Try it in 60 seconds
Sign in, create an endpoint, forward its webhooks to your machine, and send it a test request. No
install needed — this uses npx (Node 22+):
With --forward, each captured event prints one line as it lands on your local server — the event
id, the target, the status it returned, and how long it took:
Drop --forward and wbhk listen opens a live view of what's arriving instead — one row per event,
with the provider it came from and whether its signature checked out:
--forward targets must be a full loopback URL (http://localhost:3000,
http://127.0.0.1:8080/webhooks). Replay a past event with
wbhk replay <event-id> --forward http://localhost:3000.
Prefer a permanent install? Pick one:
Full walkthrough: docs.webhook.co/quickstart.
What you get
A permanent, signed URL that captures first. Every request is written to durable storage the instant it lands — before verification or dedup run — so a bad signature, an unknown provider, or a downstream outage only changes what happens next, never whether you have the event. The ingest URL is a sealed credential you can re-read on demand and rotate in place, not a secret shown once.
Verification for 144 providers, built in. One open registry
(packages/webhooks-spec) covers Stripe, GitHub, Shopify, Slack, Twilio,
Square, PayPal, Discord, Clerk, Supabase, and many more.
Every event is sorted into one of four states — verified (a cryptographic signature checked),
authenticated (source proven by a shared secret, no payload signature), failed (a signature
was checked and rejected), or unattempted — and a failure names the likely cause instead of
stopping at "no signatures found." Signing and verification follow the
Standard Webhooks spec, for both receive and send.
That registry is also a standalone library, usable without an account — or this product:
See packages/webhooks-spec for the full API. A provider it doesn't cover
yet is usually one config row — that's a
good first issue.
Reliable outbound delivery. Forward captured events to your own destinations with strict FIFO
ordering (one Durable Object per destination), at-least-once delivery, retries on exponential backoff,
and dead-lettering once a destination exhausts its retries. Deliveries carry a fresh signature only
for events webhook.co verified or authenticated; anything it couldn't vouch for is relayed unsigned.
Optional per-endpoint deduplication collapses repeats by Standard-Webhooks id, provider event id, a
content hash, or JSON fields you choose.
Replay on demand. Re-send any captured event still within your retention window — to localhost or to a registered destination — to fix a handler or recover from an outage, without asking the provider to send it again.
Private by default, with the controls built in. Nothing is public unless you make it so. Tenant
isolation is enforced by Postgres row-level security; secrets are envelope-encrypted under a KMS;
traffic is encrypted in transit and at rest; and privileged actions land in an append-only,
hash-chained audit log with a verifier (wbhk audit verify) that proves the chain hasn't been
altered.
One capability contract, four surfaces. Every capability is defined once and bound identically to the CLI, the REST API, the web dashboard, and the MCP server. A parity gate fails the build if a surface forgets one — so the surfaces don't drift.
Built for agents
An agent can act on inbound webhooks without you writing the plumbing. The
MCP server at mcp.webhook.co is a first-class surface
(remote HTTP on Cloudflare Workers, OAuth-authorized), and triggers.wait is the primitive: an agent
registers a trigger on an endpoint and drains new events since its last cursor — at-least-once, in
capture order per endpoint, held durably while the agent is offline, with the verified payload inline
(up to 64 KiB). It is a short poll the agent drives, not a push: MCP has no native inbound trigger,
so nothing calls your agent — it calls us, and the durable log means an offline agent misses nothing.
Egress-configuring capabilities (registering replay destinations and subscriptions) are deliberately kept off MCP, and localhost replay stays CLI-only — a confused-deputy and SSRF precaution, not a missing feature.
SDKs and CLI
Three official client SDKs, generated from the same OpenAPI contract as the API, plus the wbhk CLI.
Each SDK ships bearer auth, bounded retries with jitter, cursor pagination, idempotency, and secret
redaction.
| Language | Install | Import |
|---|---|---|
| TypeScript | npm install @webhook-co/sdk | import { WebhookClient } from "@webhook-co/sdk" |
| Python | pip install webhook-co | from webhook_co import WebhookClient |
| Go | go get github.com/webhook-co/webhook-go | import webhook "github.com/webhook-co/webhook-go" |
| CLI | brew install webhook-co/tap/wbhk | the wbhk command |
The TypeScript SDK runs anywhere fetch does (Node 18+, browsers, Deno, Bun, Workers). The Python
SDK needs Python 3.10+. The Go SDK needs Go 1.22+ and has zero third-party dependencies — standard
library only — and lives in its own repository,
webhook-co/webhook-go.
The REST API lives at https://api.webhook.co/v1, authenticated with a whk_ bearer key, and is
described by a machine-readable OpenAPI 3.1 document at
api.webhook.co/openapi.json — the one source that also
generates the SDKs and the docs.
Distribution is independently verifiable: npm packages are published with provenance
(npm audit signatures), and the standalone CLI binaries carry sigstore-signed SLSA build provenance
(gh attestation verify wbhk-<os>-<arch> --repo webhook-co/webhook).
Pricing
webhook.co is free to start: a permanent signed URL, inspect, and replay, with 5,000 events to
spend once — a real trial allowance that never resets. Paid plans (Pro, Scale, Enterprise) price on
a single dimension — events — with a soft cap that pauses capture rather than surprising you
with a bill. The whole receive → verify → deliver → replay pipeline, outbound delivery included, is
on every plan; plans differ by event volume and retention window. Full numbers:
webhook.co/pricing.
How it's built
webhook.co is a Turborepo + pnpm-workspaces monorepo. The core engine is TypeScript on Cloudflare
Workers; ordering and isolation come from one Durable Object per destination, with Durable Object
Alarms driving retry scheduling; metadata and dedup live in Neon Postgres via Hyperdrive; and payloads
are stored content-addressed in R2. Ingestion runs on a separate registrable apex, wbhk.my —
cookieless, no CORS, path-token routed, with a 404 for unknown tokens — deliberately isolated from
the primary application domain.
AGENTS.md is the constitution — the shared context, conventions, and non-negotiables
every contributor and coding agent follows.
Open core
The core — the delivery/ingestion engine, the CLI and replay client, the MCP server, the SDKs, and
the Standard-Webhooks signing implementation — is Apache-2.0. Proprietary features live behind the
ee/ fence and are excluded from self-host builds; open-core code never imports from ee/.
Open source exists here for transparency and trust; an open, shared webhook interop standard — not a
restrictive license — is the point.
If this is useful to you, a ⭐ helps. It is the signal other developers use to decide whether a webhook tool is worth their afternoon, and it is the only one we can't write ourselves.
Contributing
Setup is pnpm install (Node 24, pinned in .nvmrc; pnpm via corepack enable). The
everyday loop:
Changes land via pull request to main behind required CI checks and a review. See
CONTRIBUTING.md for the full setup, the check gate, and the merge model. Issues
and discussions are welcome, and everyone taking part is held to the
Code of Conduct.
Looking for somewhere to start? The
good first issue
label is where we park the small, self-contained ones.
Security
Please report vulnerabilities privately — see SECURITY.md. Don't open a public issue
for a security report.
License
Apache-2.0 for the open core. See NOTICE for attribution and the
ee/ directory for the separately-licensed proprietary components.
Docs: docs.webhook.co · Playground: webhook.co/play · Changelog: docs.webhook.co/changelog