# Secutils.dev Tools

> Free, no-signup, single-page developer and security tools. Each tool
> publishes a SKILL.md companion at <url>.md (Claude Code / Cursor
> compatible) describing how to drive it from an AI agent, including
> the URL-state wire format where applicable.

## Tools

- [Certificate Decoder](https://tools.secutils.dev/pem.md): Decode PEM X.509 certificate chains. Subject, issuer, SANs, validity, fingerprints. Auto-sorts chain order. Shareable URL state.
- [HTTP Echo / Mock Response](https://tools.secutils.dev/echo.md): Build a fully customizable mock HTTP response (status, headers, body) and serve it as a shareable URL. State in URL, no signup.
- [JWT Debugger](https://tools.secutils.dev/jwt.md): Decode, verify, and sign HMAC JSON Web Tokens (HS256, HS384, HS512). Real-time signature validation, shareable URL state, no signup.
- [Markdown to HTML](https://tools.secutils.dev/md-to-html.md): Convert Markdown to self-contained HTML or print-ready PDFs with live preview and syntax highlighting. Shareable URL state, no signup.
- [SAML Decoder](https://tools.secutils.dev/saml.md): Decode Base64 SAML responses, requests, and metadata. Pretty-printed XML or attribute table. Shareable URL state, no signup.

## Wire format

Most tools deep-link via the URL fragment using a single shared encoding
(deflate-raw + 4-byte LE u32 ulen prefix + base64url, of UTF-8 string or
JSON.stringify(state)). Each SKILL.md includes a runnable Node snippet to
produce the URL. Reference and full spec:
https://github.com/secutils-dev/secutils/blob/main/dev/tools/AGENTS.md#url-state-encoding-encodestate--decodestate

Index: https://tools.secutils.dev/