Observatory-style grades
Starts at 100, applies penalties then bonuses, and maps to A+ … F buckets with a LOW/MEDIUM likelihood indicator.
npm package · MIT · Node ≥ 18
header-sentinel
Fail CI when deployed URLs ship weak HTTP security headers.
Scans live URLs for HSTS, CSP, COOP, frame protection, cookies and more, then gives you a specific fix for every problem, with Nginx, Express, Vercel and Netlify hints. Mozilla HTTP Observatory-style grades from A+ to F. Zero runtime dependencies.
npm i -D header-sentinel
$ npx header-sentinel https://github.com --no-http-upgrade --no-preload-check https://github.com/ (HTTP 200) Grade B+ score 80/100 · MEDIUM risk ⚠ warn CSP style-src allows 'unsafe-inline' [csp-unsafe-inline] ...
The problem
Security headers drift. A CDN change, a new reverse proxy or a framework upgrade quietly drops HSTS or loosens your CSP, and nobody notices until an audit.
header-sentinel checks the headers your deployed site actually sends, grades them the way Mozilla HTTP Observatory does, and fails the build with a concrete fix, so regressions get caught in CI rather than in a pentest report.
Features
A fix for every finding
Each problem comes with an example header plus Nginx, Express, Vercel and Netlify hints.
HSTS & redirects
Checks max-age ≥ 1 year, includeSubDomains, preload eligibility, and HTTP→HTTPS redirect chains.
CSP lint
Flags missing CSP, unsafe-inline / unsafe-eval, overly broad wildcards and missing directives.
Baseline mode
Record accepted findings once, then only fail on new issues in PRs and nightly runs.
Sitemap scanning
Load every URL from sitemap.xml with --sitemap, repeatable.
JSON & SARIF
--json exposes score, grade and observatory tests; --sarif feeds GitHub code scanning.
Zero dependencies
Node ≥ 18, ESM and CommonJS, with generated TypeScript types.
Usage
# Ad-hoc scan
npx header-sentinel https://example.com# Record a baseline on main
npx header-sentinel https://example.com --baseline .header-baseline.json --update-baseline# Fail only on new issues
npx header-sentinel https://example.com --baseline .header-baseline.json --fail-on error# Scan a whole sitemap
npx header-sentinel --sitemap https://example.com/sitemap.xml --baseline .header-baseline.jsonCI / GitHub Action
name: Security headers
on:
deployment_status:
schedule: [{ cron: '0 6 * * 1' }]
workflow_dispatch:
permissions: { contents: read, security-events: write }
jobs:
headers:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: MrLouisWright/header-sentinel@v1
with:
urls: https://example.com https://example.com/login
fail-on: error
sarif: header-sentinel.sarif
- uses: github/codeql-action/upload-sarif@v3
if: always()
with: { sarif_file: header-sentinel.sarif }Options & flags
| Flag | Description |
|---|---|
-c, --config <file> | JSON config (default: .headerguardrc.json / .headersentinelrc.json if present) |
--fail-on <level> | error | warn | none (default: error) |
--json | Print JSON results (includes observatory score/tests) |
--sarif [file] | Print SARIF 2.1.0 (or write to file) |
--sitemap <url> | Load URLs from sitemap.xml (repeatable) |
--baseline <file> | Only fail on findings not in baseline |
--update-baseline | Write current fingerprints to --baseline |
--no-http-upgrade | Skip HTTP→HTTPS redirect analysis |
--no-preload-check | Skip HSTS preload list / eligibility lookups |
-t, --timeout <ms> | Request timeout (default: 10000) |
-H, --header "K: V" | Extra request header (repeatable) |
--no-follow-redirects | Check the first response instead of the final one |
Full reference, config file format and API in the README.
Support this project
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I build free, open-source tools that help developers ship safer websites. Every coffee helps keep them maintained, documented and free for everyone.
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