JSON / API Viewer Pro

Local-first JSON & API workbench: viewer, jq/JSONPath, diff, breaking-change detection, types and tests from API responses.

JSON / API Viewer Pro turns your browser into a complete JSON and API workbench. Open any JSON from a web page, file, clipboard, or the DevTools Network panel to read, query, compare, and validate your data entirely locally. READ AND INSPECT ANY DATA • Multiple views: Tree, code, raw format, tables, statistics, and graphs • Optimized for large documents with background parsing and virtualized rendering • Search keys, values, or paths using regular expressions and custom case settings • Copy paths, values, or code snippets for your scripts • Repair broken JSON with an instant preview before applying changes • Edit, rename, and delete nodes with full undo support • Open popular data exchange formats and JSONP directly • Automatically inspect dates, timestamps, UUIDs, JWTs, colors, and images QUERY AND TRANSFORM • Built-in querying with JSONPath, JMESPath, and jq support • Display results as JSON or tables; export, flatten, group, or deduplicate data • Save frequent queries and view historical runs COMPARE AND DIFFERENTIALS • Structural diffs by path: highlight added, removed, or modified values and types • Side-by-side and unified diff views with advanced 3-way comparisons • Option to ignore specific paths, key ordering, or small numerical differences API WORKFLOW & DEVTOOLS • Dedicated DevTools panel captures JSON responses from active browser tabs • Endpoint timeline lines up responses over time to compare against previous runs • Contract diffing flags breaking changes such as missing fields or altered types • Set baselines to automatically validate subsequent API responses • Track API changelogs, import session logs, replay requests, and manage OpenAPI specs • Personal data scanner helps locate and mask sensitive information in one click SCHEMAS, CODE GENERATION, AND TESTING • JSON Schema validation with direct error path mapping; generate schemas from samples • Automatically generate type definitions for popular programming languages • Convert real responses into API test suites and mock data generators • Convert JSON into structured tables, markup, or request query strings PRIVATE BY DESIGN • No user accounts, analytics, telemetry, or ads • Documents and snapshots remain on your machine • Sensitive tokens, passwords, and authorization headers are auto-redacted • Website permissions are strictly optional and requested per site only when needed BUILT FOR DAILY USE • Command palette and customizable keyboard shortcuts • Side panel integration, right-click context menu options, and multi-tab management • Dozens of visual color themes with custom CSS support • Multilingual UI support FREE AND PRO EDITIONS The free version provides essential JSON viewing, path queries, structural diffs, schema validation, and basic code generation. Upgrading to Pro unlocks large-file performance optimizations, complete API workflows, extended code generators, and unlimited history.