# Developer & data tools

> A network of 15 focused, deterministic tools. Every tool has a human page, a JSON API, an OpenAPI description and an MCP tool that all return the same result (inputs, result, units, assumptions, sources, timestamps).

## Machine interfaces
- Tool catalog (JSON): https://developer.usefulweb.app/api/v1/tools
- OpenAPI (all tools): https://developer.usefulweb.app/openapi.json
- MCP server (all tools + workflows): https://developer.usefulweb.app/mcp
- Pick a tool for a natural-language request: POST https://developer.usefulweb.app/api/v1/tools/prompt-to-tool-router/calculate {"request": "..."}

## Tools
- [HeaderLens](https://headerlens.usefulweb.app/): Is a website down? Multi-region status, redirects, TLS and security headers. API: POST https://developer.usefulweb.app/api/v1/tools/headerlens/calculate
- [Accessibility Snapshot](https://a11ysnapshot.usefulweb.app/): Static WCAG 2.2 snapshot of a page: findings by severity, evidence and manual checks. API: POST https://developer.usefulweb.app/api/v1/tools/a11y-snapshot/calculate
- [Browser Compatibility Checker](https://browsercompatibilitychecker.usefulweb.app/): Which browsers support a CSS property, JS API or HTML element? MDN data + Baseline status. API: POST https://developer.usefulweb.app/api/v1/tools/browser-compatibility-checker/calculate
- [CiteShape](https://citeshape.usefulweb.app/): Paste a DOI, ORCID iD, ISBN or arXiv ID: validated, resolved, and formatted as APA, BibTeX and RIS. API: POST https://developer.usefulweb.app/api/v1/tools/citeshape/calculate
- [CyberChef-lite Pipeline](https://cybercheflitepipeline.usefulweb.app/): One-click decoding recipes: JWT, base64 → gunzip → JSON, double URL decode, hex dump. API: POST https://developer.usefulweb.app/api/v1/tools/cyberchef-lite-pipeline/calculate
- [DataFresh](https://datafresh.usefulweb.app/): Is this dataset or API still fresh? Newest record, update cadence check and schema drift. API: POST https://developer.usefulweb.app/api/v1/tools/datafresh/calculate
- [FileFit](https://filefit.usefulweb.app/): Can this app open, edit or convert that file format? Verified facts with sources. API: POST https://developer.usefulweb.app/api/v1/tools/filefit/calculate
- [LocaleKit Country Format Rules](https://localekit.usefulweb.app/): Address form fields, postal-code regex, calling code and date formats for any country. API: POST https://developer.usefulweb.app/api/v1/tools/localekit/calculate
- [Network Speed Tester](https://networkspeedtester.usefulweb.app/): Measure latency, jitter, download and upload speed between your browser and our server. API: POST https://developer.usefulweb.app/api/v1/tools/network-speed-tester/calculate
- [RuleDate Deadline Calculator](https://ruledate.usefulweb.app/): Business-day and deadline maths with public holidays and a step-by-step rule trace. API: POST https://developer.usefulweb.app/api/v1/tools/ruledate/calculate
- [Safe Markdown Preview](https://safemarkdownpreview.usefulweb.app/): Render Markdown with GFM tables and footnotes to sanitised HTML and see what was removed. API: POST https://developer.usefulweb.app/api/v1/tools/safe-markdown-preview/calculate
- [TimeFair Meeting Planner](https://timefair.usefulweb.app/): Find fair meeting times across time zones, with DST-exact local times and rotation. API: POST https://developer.usefulweb.app/api/v1/tools/timefair/calculate
- [Unicode Inspector](https://unicodeinspector.usefulweb.app/): Every code point with name, script and bytes, plus hidden characters and look-alikes. API: POST https://developer.usefulweb.app/api/v1/tools/unicode-inspector/calculate
- [UnitProof Unit Calculator](https://unitproof.usefulweb.app/): Unit maths you can audit: dimension check, exact factors and a full derivation tree. API: POST https://developer.usefulweb.app/api/v1/tools/unitproof/calculate
- [Unix Permission Calculator](https://unixpermissioncalculator.usefulweb.app/): chmod calculator: octal ↔ rwx, setuid/sticky, u+x style changes, umask and ls -l. API: POST https://developer.usefulweb.app/api/v1/tools/unix-permission-calculator/calculate

## Workflows