JASON (JSON Manager) by StefanoStem
JASON (JSON Manager) is a local-first JSON workspace that lives in your browser sidebar and is built for developers, QA, API testers, and technical users who work with JSON all day.
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About this extension
What is it
A focused side-panel tool for:
- Collecting JSON-like payloads from active pages,
- Storing and organizing snippets in tabs,
- Validating/formatting/minifying content,
- Comparing two payloads with visual diff guidance.
How you use it
Three core modes:
- Store:
- tabbed JSON workspace (edit, search, fold, format, save, download).
- Compare:
- two JSON fields side by side, run comparison, inspect line/word-level diffs, and confirm perfect matches.
- Capture:
- run scan on current tab, review results, store or compare selected captures.
Why
- Reduces context switching between devtools, editors, and scratchpads.
- Keeps JSON workflows in one persistent place.
- Improves review speed with inline compare visuals and searchable content.
UI/UX
- Local persistence with fast reopen behavior.
- Light/dark theme support.
- Real-time size/validation feedback.
- Search across workspace content and capture content.
- Scan flow includes user feedback and retry behavior for common tab-readiness timing cases.
Privacy and architecture
- No analytics, no third-party telemetry, no external data transmission.
- Data stays in browser local storage.
- Plain JS architecture with shared source + browser-specific manifests/background scripts.
- Deterministic build pipeline with manifest sync checks.
A focused side-panel tool for:
- Collecting JSON-like payloads from active pages,
- Storing and organizing snippets in tabs,
- Validating/formatting/minifying content,
- Comparing two payloads with visual diff guidance.
How you use it
Three core modes:
- Store:
- tabbed JSON workspace (edit, search, fold, format, save, download).
- Compare:
- two JSON fields side by side, run comparison, inspect line/word-level diffs, and confirm perfect matches.
- Capture:
- run scan on current tab, review results, store or compare selected captures.
Why
- Reduces context switching between devtools, editors, and scratchpads.
- Keeps JSON workflows in one persistent place.
- Improves review speed with inline compare visuals and searchable content.
UI/UX
- Local persistence with fast reopen behavior.
- Light/dark theme support.
- Real-time size/validation feedback.
- Search across workspace content and capture content.
- Scan flow includes user feedback and retry behavior for common tab-readiness timing cases.
Privacy and architecture
- No analytics, no third-party telemetry, no external data transmission.
- Data stays in browser local storage.
- Plain JS architecture with shared source + browser-specific manifests/background scripts.
- Deterministic build pipeline with manifest sync checks.
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Permissions and data
Required permissions:
- Access browser tabs
- Access your data for all websites
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 1.2.0
- Size
- 61.47 KB
- Last updated
- 6 days ago (Apr 12, 2026)
- Related Categories
- License
- MIT License
- Version History
- Add to collection
The developer of this extension asks that you help support its continued development by making a small contribution.