DevPouch
Local developer, API and QA tools
Validate contracts, compare structured data, test GraphQL and XML, and debug browser HTTP behavior without sending pasted tool input to a processing server.
Find a tool
Search the most-used tools or jump into the full directory.
10 tools found
OpenAPI Validator
Validate OpenAPI 3.x syntax, required structure, operations, and local references.
Open toolJSONJSON Schema Validator
Validate JSON syntax separately from a JSON Schema Draft 2020-12 contract.
Open toolAPIOpenAPI Diff and Breaking Change Analyzer
Compare old and new OpenAPI 3.x contracts with conservative compatibility classifications.
Open toolQAOpenAPI Test Matrix Generator
Turn declared OpenAPI constraints into traceable QA test ideas.
Open toolHTTPHTTP Header Analyzer
Parse a raw header block and redact a documented set of common credential-bearing fields.
Open toolHTTPCORS Analyzer
Model a browser CORS scenario from request context and pasted response fields.
Open toolJSONJSON Formatter
Pretty print JSON and make nested data easier to read.
Open toolDiagramMermaid Diagram Renderer
Write Mermaid source, preview a sanitized diagram, and export SVG or PNG.
Open toolYAMLYAML Formatter
Parse and format YAML while preserving comments where the parser supports them.
Open toolQAJSON / YAML Deep Diff
Compare parsed JSON or YAML structures rather than line-oriented text.
Open toolChoose a workbench
Focused tools and practical guides for common developer and QA investigations.
Featured QA and API tools
Contract validation, compatibility analysis, test design, and browser HTTP diagnostics.
OpenAPI Validator
Validate OpenAPI 3.x syntax, required structure, operations, and local references.
Open toolJSONJSON Schema Validator
Validate JSON syntax separately from a JSON Schema Draft 2020-12 contract.
Open toolAPIOpenAPI Diff and Breaking Change Analyzer
Compare old and new OpenAPI 3.x contracts with conservative compatibility classifications.
Open toolQAOpenAPI Test Matrix Generator
Turn declared OpenAPI constraints into traceable QA test ideas.
Open toolHTTPHTTP Header Analyzer
Parse a raw header block and redact a documented set of common credential-bearing fields.
Open toolHTTPCORS Analyzer
Model a browser CORS scenario from request context and pasted response fields.
Open toolPopular structured-data tools
Format, compare, validate, and visualize JSON, YAML, and technical diagrams locally.
JSON Formatter
Pretty print JSON and make nested data easier to read.
Open toolDiagramMermaid Diagram Renderer
Write Mermaid source, preview a sanitized diagram, and export SVG or PNG.
Open toolYAMLYAML Formatter
Parse and format YAML while preserving comments where the parser supports them.
Open toolQAJSON / YAML Deep Diff
Compare parsed JSON or YAML structures rather than line-oriented text.
Open toolLearn with cornerstone guides
Detailed handbooks for API testing, OpenAPI, payload debugging, browser security, and compatibility, with documented reference checks.
Complete API Testing Guide for QA Engineers
A field guide for turning API contracts, risks, and failure evidence into maintainable exploratory and automated coverage.
OpenAPI Testing Handbook
A practical handbook for turning an OpenAPI description into review evidence and contract-derived QA work without confusing the document with the running API.
Browser Network Debugging Handbook
Trace browser API failures through HAR timing, HTTP messages, cookies, CSP, CORS, caching, and redacted evidence.
Structured Data Testing Handbook
Work through JSON, JSONPath, schema inference, NDJSON, CSV, diffs, and type generation with explicit data-loss boundaries.
GraphQL API Testing Handbook
Design GraphQL tests across syntax, operation selection, variables, fragments, errors, authorization, and runtime limits.
XML API Testing Handbook
Debug XML transport, well-formedness, namespaces, XPath selection, conversion, and schema boundaries.
Categories
Privacy-first
Tool input stays in the browser for processing. There are no backend routes for transforming user data.
No signup
Open a compact pouch of useful developer tools, paste input, copy output, and keep moving without account friction.
QA-focused and source-aware
Tools create reviewable QA evidence, while guides cite authoritative technical references and state implementation limits.
FAQ
Are these developer tools free?
Yes. The app is built as a free browser-based utility site with no account requirement.
Is tool input uploaded?
No. Interactive tools process input locally in the browser wherever possible and do not send tool input to a backend.
Can I paste secrets into tools?
Be careful with secrets in any online tool. DevPouch tools are designed for browser-local processing, but your device, browser, extensions, clipboard, and data sensitivity still matter.