The only scanner laser-focused on webhook signature verification.
Local. Deterministic. Zero-network. JS/TS + Python + PHP. Five minutes from npx to fix.
npx hookwarden scan ./your-appNo traffic leaves your machine. No telemetry. No SaaS sign-up required.
📖 Full documentation: docs.hookwarden.dev
Every Sunday at 22:00 UTC, this repo's CI runs hookwarden against 45 popular open-source projects — currently cal.com, documenso, formbricks, twenty, plane, unkey, typebot, papermark (full target list, combined ★190k+) — to prove the scanner works on real production code.
Latest sweep — 2026-05-28 · 21/45 projects clean (zero critical/high)
| Provider | 🚨 critical | 🟡 manual-review | Rules that fired | |
|---|---|---|---|---|
| Stripe integrations | 8 | 0 | 1 | stripe/hardcoded-secret-prefix (×2)stripe/missing-signature-verification (×4)stripe/raw-body-misuse (×2)stripe/unreachable-verification (×1) |
| GitHub integrations | 0 | 0 | 0 | — |
| Shopify integrations | 0 | 0 | 0 | — |
| Slack integrations | 7 | 0 | 0 | slack/missing-signature-verification (×7) |
| Twilio integrations | 0 | 0 | 0 | — |
| Square integrations | 0 | 0 | 0 | — |
| Engine signals (parse errors) | 0 | 0 | 67 | engine/parse-error (×67) |
These are bugs in the webhook handlers that receive provider events — flaws in the integrating projects' integration code, not in Stripe / GitHub / Shopify / Slack / Twilio / Square themselves.
Hookwarden checks 11 rule classes across 21 providers — most of the corpus handles webhooks correctly, hence the short list. The full rule catalog lives in the docs.
Per-target findings are never published before responsible disclosure — see methodology. To run the same scan against your own code:
npx hookwarden scan ./your-appEvery dollar of fraud that flows through a webhook starts with a verification bug — and verification bugs hide in plain sight.
A handler that accepts an unsigned payload, compares HMACs with ==, or skips the signature check on a ?test=true path silently routes attacker traffic into your business logic. The bug is one line in a 50K-line app, and it looks plausible — not the shape general-purpose SAST tools are tuned to flag. They were built for SQL injection and prototype pollution; webhook verification falls between their default rule packs.
hookwarden does one thing. It walks your repo, parses every webhook handler across 11 frameworks, and labels each one verified, not-verified, or manual-review — with the exact file, line, and a fix quoted from provider docs. The catalog (21 named providers — Stripe, GitHub, Shopify, Slack, Twilio, Square, Sentry, Zendesk, DocuSign, PagerDuty, Notion, Auth0, HubSpot, Intercom, Linear, Zoom, Calendly, Bitbucket, Mailchimp, Postmark, plus Standard Webhooks conformant providers like Clerk, Resend, Mux) encodes signature quirks no generic scanner has the surface area to know: Stripe's 5-minute timestamp tolerance, Slack's v0:${ts}:${body} scheme, Twilio's SHA-1 outlier.
The three-state verdict is not a hedge. manual-review is what you get when hookwarden can't prove safety or unsafety from the source alone — a handler inside a middleware chain the analyzer couldn't unroll, say. It's how the false-positive rate stays honest (<5%, measured against a 200-repo OSS corpus). A tool that reports every gray area as a bug isn't a security tool; it's noise. → How the verdict works
npx hookwarden scan . # works everywhere, no installOr install natively:
| OS | Recommended | Alternates |
|---|---|---|
| Linux | brew install Hookwarden/tap/hookwarden |
npm i -g hookwarden · pip install hookwarden · direct binary |
| macOS | brew install Hookwarden/tap/hookwarden |
npm i -g hookwarden · npx hookwarden |
| Windows | scoop bucket add hookwarden https://github.com/Hookwarden/scoop-bucket && scoop install hookwarden |
npm i -g hookwarden · pip install hookwarden |
Node 22+ is required for the npm/npx/macOS-brew paths; the standalone binaries (Linux x64/arm64, Windows x64) bundle the runtime. Direct binary downloads are intentionally unsigned (Gatekeeper / SmartScreen will warn) — prefer brew / scoop / npm / pip, which verify by SHA-256. → Install guide
hookwarden --version # check what you have| Channel | Command |
|---|---|
| brew (macOS/Linux) | brew upgrade hookwarden |
| scoop (Windows) | scoop update hookwarden |
| npm (global) | npm i -g hookwarden@latest |
| pip | pip install -U hookwarden |
| npx (no install) | npx hookwarden@latest scan . — @latest bypasses the npx cache |
| direct binary | re-download from Releases |
Rule pack versions move with the CLI (engine, rules, and CLI ship as a fixed group — 0.7.5 everywhere). Pin in CI with npx hookwarden@0.7.5 scan . if you want byte-stable verdicts across runs.
# Scan — no install required
npx hookwarden scan ./your-app
# Fail CI on high+ findings, machine-readable output
npx hookwarden scan ./your-app --fail-on high --format json
# Exit codes: 0 clean · 1 findings at threshold · 2 engine error · 3 config error · 4 parse coverage below floor
# Adopt on a non-greenfield repo — accept existing findings, gate only NEW ones
npx hookwarden scan ./your-app --baseline write
npx hookwarden scan ./your-app --fail-on high
# List every detected webhook handler (no rules run) — useful for audits
npx hookwarden inventory ./your-app--diff-only, --provider stripe,github (phased rollout), --include/--exclude globs, --strict-suppressions, repo-level hookwarden.config.yaml, and more: npx hookwarden --help and the CLI docs.
hookwarden doesn't just name the fix — it applies it. The fix subcommand mechanically rewrites the safety: safe subset across JS/TS, Python, and PHP (42 rules covering timing-unsafe comparisons → crypto.timingSafeEqual / hmac.compare_digest / hash_equals, and raw-body misuse). The other 188 rules are architectural and emit per-finding fix prose instead.
npx hookwarden fix ./your-app # dry-run — prints a unified diff, writes nothing
npx hookwarden fix ./your-app --write # atomic staging, re-scan, then rename into placeEvery rewrite lands in a staging dir and is re-scanned before replacing the original; the fixer never edits inside strings or comments. → hookwarden fix · Safety levels
Captured verbatim — each line is what you'll see in your terminal, not a mockup. One Express middleware bug produces three findings, because that single mistake violates three distinct invariants; fixing one (re-ordering the middleware) clears all three:
$ hookwarden scan ./your-app
× critical server.js:10:1 stripe/express-middleware-ordering not-verified
Express webhook handler for Stripe has `express.json()` registered before the webhook route. JSON
middleware consumes the request body; by the time the Stripe handler runs, the raw bytes used for
HMAC are gone and `stripe.webhooks.constructEvent` cannot reproduce the signature.
fix › register `express.json()` AFTER the webhook route, OR mount `express.raw(...)` on the path only.
docs › https://docs.stripe.com/webhooks#verify-events
refs › https://expressjs.com/en/guide/using-middleware.html
https://www.svix.com/blog/common-failure-modes-for-webhook-signatures/
× critical server.js:10:1 stripe/missing-signature-verification not-verified
Stripe webhook handler does not appear to verify the signature header before processing the event …
× critical server.js:10:1 stripe/raw-body-misuse not-verified
Stripe webhook handler reads the signature header but does not appear to receive the body as raw bytes …
────────────
Found 3 critical · 0 high · 0 medium · 0 low · 0 info · 0 manual-review — 1 webhook handler across 1 file
Scanned in 3 ms · 1 / 1 candidates parsed (100.0% coverage)
| Glyph | Severity | SARIF level | Counts toward --fail-on? |
|---|---|---|---|
× |
critical |
error |
yes |
! |
high |
error |
yes |
▲ |
medium |
warning |
yes |
· |
low |
note |
yes |
i |
info |
note |
no — informational (e.g. library-verified) |
The state column is the three-state verdict. Output is also available as byte-stable JSON and SARIF 2.1.0 (round-trips through GitHub Code Scanning, dedupes via partialFingerprints). → Output formats & JSON schema
3 languages · 11 frameworks · 21 providers · 230 rules · 100% cited. Every rule carries ≥1 external citation (CWE / RFC / Svix / Stripe spec) alongside the provider's own docs — auditors and reviewers can follow any finding back to a stable external source. JS/TS parse with Babel; Python and PHP with tree-sitter (WASM).
| Language | Frameworks |
|---|---|
| JavaScript / TypeScript | Express · Hono · Fastify · Next.js |
| Python | Flask · FastAPI · Django |
| PHP | Laravel · Symfony · Slim · vanilla single-file |
Every rule carries fix guidance quoted from the provider's canonical security docs. Full per-rule reference and coverage matrix: docs.hookwarden.dev/rules.
# .github/workflows/hookwarden.yml
name: hookwarden
on: [pull_request, push]
permissions:
contents: read
pull-requests: write
security-events: write
jobs:
scan:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
with: { fetch-depth: 0 }
- uses: Hookwarden/hookwarden-action@v1
with:
fail-on: highUploads SARIF to Code Scanning automatically; findings appear as PR annotations. Raw-CLI + SARIF-upload recipe, exit-code matrix, and diff-only PR scans: → CI integration guide.
hookwarden is specialized on purpose. The general-purpose scanners below are excellent — they're just not in this fight.
| Tool | What it does well | Webhook verification |
|---|---|---|
| semgrep | General-purpose SAST; flexible rules | Low signal — generic matching misses body-parsing order, timing-safe paths, SDK flows |
| snyk Code | Broad vuln detection (paid SaaS) | No webhook rules; doesn't model HMAC reachability |
| GitGuardian / TruffleHog | Secret-leak detection | Finds hardcoded secrets; doesn't audit whether verification is correct |
| Datadog Static Analysis | Broad SAST; good cloud signal | No webhook specialization; low-signal for this bug class |
| hookwarden | Webhook verification logic only | 230 rules (100% cited), 21 providers, three-state verdicts, <5% FP on a 200-repo corpus |
hookwarden is not a general-purpose SAST or DAST scanner — it won't find XSS, SQL injection, or memory-safety bugs, and it isn't trying to. Keep semgrep, CodeQL, or your DAST for those. Already running one? hookwarden is additive — it finds the one class of bug they weren't built to catch.
@hookwarden/mcp is a Model Context Protocol server that gives AI coding agents the scan_handler tool. Paste in any webhook handler, get back the same 3-state verdict (verified / not-verified / manual-review) the CLI would emit — fully local, deterministic, no traffic leaves the agent's machine.
npx @hookwarden/mcp init # auto-detects Claude Desktop / Cursor / Continue and writes the configThe rule pack is bundled inline, content-hashed, and version-pinned to the engine — scan_handler cross-checks both on every call and fails loudly on drift. → @hookwarden/mcp on npm
A pnpm monorepo with a strict, CI-enforced dependency boundary: the engine is pure-functional (no I/O, no filesystem, no network), so the same engine runs in the CLI, in CI, in the MCP server, and — eventually — in a browser playground without modification.
| Package | Purpose | License |
|---|---|---|
@hookwarden/engine |
Handler discovery, reachability analysis, evidence collection. Pure-functional, browser-safe. | Apache 2.0 |
@hookwarden/rules |
Provider catalog, YAML rule packs, parameterized predicate factories. | Apache 2.0 |
@hookwarden/fix |
Auto-remediation — bounded location for AST mutation (Babel traverse + generator). | Apache 2.0 |
@hookwarden/mcp |
Model Context Protocol server — scan_handler tool for AI coding agents. |
Apache 2.0 |
hookwarden |
CLI binary — reads config, drives the engine, renders text/JSON/SARIF. | Apache 2.0 |
dependency-cruiser enforces the engine's I/O boundary in every PR.
- ✅ v0.8 —
@hookwarden/mcpdeveloper preview (Model Context Protocol server exposingscan_handlerto Claude Code, Cursor, Continue, and the Anthropic Agent SDK — pasted handler code returns a 3-state verdict locally, zero-network, deterministic). → MCP server - ✅ v0.7.2 — references visible in output (text renderer gains a
refs ›block per finding; JSON envelope gainsscan.findings[].references: string[]. v0.7.1 cited every rule; v0.7.2 makes citations actually visible to scan consumers). - ✅ v0.7.1 — rule-pack polish (references backfilled on 142 grandfathered rules → 230 cited; test-path severity overrides on 219 rules → test fixtures no longer false-fire as critical/high).
- ✅ v0.7 — Rule Depth (5 new rule classes: VAS / BYP / ERS / LEAK / RPL families across 21 providers; rule pack grew 142 → 230).
- ✅ v0.6 — rule-pack expansion (15 new provider rule packs incl. Zendesk, DocuSign, PagerDuty, Bitbucket, Notion, Calendly, Zoom; Standard Webhooks spec sweep covers Clerk, Resend, Mux, Lob, etc.; CVE-2026-41432 Stripe empty-secret detector).
- ✅ v0.5 —
hookwarden fixauto-remediation (mechanical AST rewrites, safe/manual-only per rule). - ✅ v0.4 — PHP support (Laravel, Symfony, Slim, vanilla) +
--providerfilter for phased rollout.
Rule-pack PRs are the highest-value contribution — adding a provider is a catalog edit plus N rule YAMLs, no new TypeScript in most cases. See the existing 21 in packages/rules/rules/ as worked examples, and CONTRIBUTING.md.
pnpm install && pnpm -r build && pnpm -r testBug reports & feature requests: open an issue. Docs: docs.hookwarden.dev · hookwarden.dev.
To add yourself after a merged PR, comment
@all-contributors please add @<username> for <contribution>.
Apache 2.0 — see LICENSE. The CLI, engine, and rule packs are open source and will stay that way. A separate closed-source SaaS tier handles continuous monitoring, secret-leak scanning, automated rotation, and SOC 2 evidence export — hookwarden.dev.