Opinionated security defaults for authentication, input handling and HTTP hardening in web apps.
# Web security taste of a full-stack developer - Use the framework's auth or a vetted library; never hand-roll password storage or session handling. Confidence: 0.95 - Hash passwords with Argon2id or bcrypt and a sensible work factor. Confidence: 0.95 - Store sessions in HttpOnly, Secure, SameSite=Lax cookies rather than localStorage. Confidence: 0.90 - Rotate the session id on login and on privilege change. Confidence: 0.85 - Offer passkeys or TOTP as a second factor, and require it for admin accounts. Confidence: 0.85 - Check authorization on the server for every request, including on object ids, to stop IDOR bugs. Confidence: 0.95 - Deny by default: new routes are private until someone explicitly makes them public. Confidence: 0.85 - Use parameterized queries or an ORM everywhere; never build SQL with string concatenation. Confidence: 0.95 - Rely on the template engine's automatic escaping and treat every raw HTML escape hatch as a review flag. Confidence: 0.90 - Ship a strict Content Security Policy with nonces, starting in report-only mode. Confidence: 0.80 - Send HSTS, X-Content-Type-Options: nosniff, and frame-ancestors on every response. Confidence: 0.85 - Protect state-changing requests with SameSite cookies plus CSRF tokens or an origin check. Confidence: 0.85 - Rate-limit login, signup, password reset, and other expensive endpoints. Confidence: 0.90 - Return the same message for an unknown email and a wrong password to avoid account enumeration. Confidence: 0.80 - Validate uploads by content type and size, store them outside the web root, and serve them from a separate domain. Confidence: 0.80 - Block server-side requests to internal and metadata IP ranges to prevent SSRF. Confidence: 0.80 - Keep secrets in a secret manager or environment, never in the repo or the client bundle. Confidence: 0.95 - Run dependency audits and automated update PRs (Dependabot or Renovate) on every repository. Confidence: 0.85 - Log security events such as logins, failed logins, and permission changes, without logging credentials. Confidence: 0.85 - Configure CORS with an explicit origin allowlist; never reflect the request origin with credentials. Confidence: 0.90 - Use short-lived, narrowly scoped API tokens and make them revocable. Confidence: 0.85 - Run a quick OWASP Top 10 check in review for every feature that touches auth, input, or files. Confidence: 0.75
Reviews HTTP caching headers (Cache-Control, Expires, ETag, Last-Modified, Vary, Set-Cookie) for pages, assets, APIs. Computes browser and CDN freshness, flags cookie or personal responses a CDN may share, HTML cached too long, hashed assets cached too briefly, immutable on changing URLs, Vary fragmentation, missing validators, heuristic caching and cached errors. Suggests a header per resource. Includes a stdlib Python checker with --self-test.
Decodes a JWT without trusting it and lints the header and claims: alg none, remote jku/x5u keys, missing or expired exp, nbf/iat clock skew, millisecond timestamps, long lifetimes, iss/aud mismatches, sensitive data in the payload, and HMAC signature checks with a secret from an env var. Use when a login or API call fails with 401, or when reviewing token settings. Includes a stdlib Python inspector with --self-test.
Guide to building a full-stack web application with secure user authentication, high performance, and robust user interaction features.
Reviews a password policy config against NIST SP 800-63B-4, covering length minimums, no composition rules or forced expiry, blocklist checks, rate limiting, paste and Unicode support, no hints or security questions, and safe hashing parameters. Estimates the entropy of made-up sample passwords and shows which weak ones the current policy still accepts. Never asks for real passwords. Includes a stdlib Python checker with --self-test.
