Free Developer Tools Online
139 free in-browser developer tools for API contracts, JSON, XML, JWT, security, and data formats. Validate OpenAPI, decode JWTs, scan for secrets, convert JSON to CSV. No signup.
Tool Categories
- API & Contract Testing Tools — Compare payloads, diff OpenAPI specs, validate naming conventions, and ensure contract consistency across API versions.
- API Security Analysis Tools — Detect secrets, PII, risky JWT configs, error leaks, and security header gaps in API payloads and specs.
- XML & SOAP Utilities — Diff XML documents, validate against XSD, test XPath, inspect SOAP envelopes, and detect XXE risks — all namespace-aware.
- OWASP API Security Tools — Map API specs and samples to OWASP API Top 10 categories — auth coverage, data exposure, mass assignment, and more.
- HAR Traffic Analysis Tools — Upload HAR files to detect auth drift, token placement issues, CORS misconfig, and undocumented endpoints from real traffic.
- API Scoring & Quality Tools — Aggregate static analysis results into weighted scores for API hygiene, completeness, and security posture.
- API Explainability Tools — Generate plain-English explanations for security findings and map them to OWASP categories for audit-ready reporting.
- Cross-Artifact Analysis Tools — Cross-reference HAR traffic against OpenAPI specs, or validate samples against schemas to detect contract drift.
- API Readiness Tools — Assess API readiness for automation and mocking — identify stable assertion candidates and mockability blockers.
- Data Format Converter Tools — Transform data between formats — flatten nested JSON to CSV, convert payloads, and reshape structures for analysis and export.
- Schema Converter Tools — Generate and convert schema definitions — infer XSD from XML, create JSON Schema from samples, and transform between schema formats.
- Developer Helper Utilities — Encode, decode, convert, and inspect data quickly — Base64, hashing, formatting, and other everyday developer utilities.
- Viewer & Formatter Tools — Format, validate, minify, and inspect JSON, YAML, TOML, XML, ENV, INI, and properties files directly in your browser.
- Encryption & Crypto Utilities — Encode, decode, hash, and transform data with URL encoding, percent-encoding, and other cryptographic and encoding utilities.
- HTTP & Networking Utilities — Inspect HTTP traffic, build requests, trace redirects, analyse CORS/cache/rate-limit headers, and signed webhooks.
- API Architecture Tools — Map API dependencies, endpoint hot spots, and retry safety from OpenAPI specs to inform design and review.
- GraphQL Utilities — Validate GraphQL SDL and queries, and draft REST endpoint mappings from GraphQL operations.
- Testing & QA Utilities — Generate mock responses, test cases, and replay scripts from OpenAPI specs, cURL, or HAR captures.