JS Disector by dukevin
Live JavaScript inspection, replay, modifying, and request/response interception, in Firefox DevTools.
Extension Metadata
About this extension
Ever open Firefox DevTools knowing the behavior you want to understand is somewhere in the page’s JavaScript, but tracing callbacks, global variables, event handlers, and network requests is more effort than the problem deserves?
JS Disector was created after one too many mandatory online training sites with unskippable videos and client-side quizzes. The JavaScript was running right in front of me, but still felt just out of reach: I could read the source, add breakpoints, and dig through objects, but there wasn’t a convenient way to watch everything happen, change it, and try it again.
JS Disector adds a runtime-inspection panel to Firefox DevTools. It lets you:
- Watch JavaScript function calls happen in real time
- Explore calls as nested trees
- Inspect arguments, values, timing, and source locations
- Edit values and replay captured calls
- Monitor and modify global variables
- Pause network requests and responses, edit them, and continue
- Disable selected functions or network endpoints
- Search, filter, and save captured behavior
- Ask an optional AI agent to analyze the evidence
It is useful for debugging unfamiliar or badly structured applications, understanding event and data flow, experimenting with browser games, and demonstrating why websites should never trust client-side state for authorization, membership, scores, or other sensitive decisions.
Also - fully open source: https://github.com/dukevin/js-disector
JS Disector was created after one too many mandatory online training sites with unskippable videos and client-side quizzes. The JavaScript was running right in front of me, but still felt just out of reach: I could read the source, add breakpoints, and dig through objects, but there wasn’t a convenient way to watch everything happen, change it, and try it again.
JS Disector adds a runtime-inspection panel to Firefox DevTools. It lets you:
- Watch JavaScript function calls happen in real time
- Explore calls as nested trees
- Inspect arguments, values, timing, and source locations
- Edit values and replay captured calls
- Monitor and modify global variables
- Pause network requests and responses, edit them, and continue
- Disable selected functions or network endpoints
- Search, filter, and save captured behavior
- Ask an optional AI agent to analyze the evidence
It is useful for debugging unfamiliar or badly structured applications, understanding event and data flow, experimenting with browser games, and demonstrating why websites should never trust client-side state for authorization, membership, scores, or other sensitive decisions.
Also - fully open source: https://github.com/dukevin/js-disector
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Permissions and data
Required permissions:
- Extend developer tools to access your data in open tabs
- Access browser tabs
- Access browser activity during navigation
- Access your data for all websites
Required data collection, according to the developer:
- Website content
More information
- Add-on Links
- Version
- 0.2.0
- Size
- 3.2 MB
- Last updated
- 11 days ago (Jul 21, 2026)
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