Live Resource Override by Sapan
Override JS, CSS, and API responses in your browser for safe debugging — without touching production.
Available on Firefox for Android™Available on Firefox for Android™
Extension Metadata
About this extension
Live Resource Override lets you intercept and modify web resources directly in your browser — no proxy tools, no production deployments, no risk.
Key Features:
- Override JavaScript, CSS, HTML, and API responses on any website
- Redirect requests to local or remote files
- Modify HTTP response headers
- Block unwanted requests
- Inject custom JavaScript and CSS into any page
- Group rules by project with enable/disable toggles
- URL matching with contains, equals, wildcard, and regex patterns
- Domain and resource type filtering
- Import/export rule configurations
- Full editor UI for managing complex rule sets
Use Cases:
- Debug production issues safely without pushing code changes
- Test JavaScript fixes before deploying to a live environment
- Mock API responses for frontend development
- Block analytics or tracking scripts during testing
- Override CSS to prototype design changes in real-time
How It Works:
Create override rules that match URLs by pattern. When a matching request is detected, Live Resource Override intercepts it and applies your modification — whether that's replacing the response body, redirecting to a different file, injecting code, or modifying headers. All changes are session-only and never touch your production environment.
Built with Manifest V3 for security and performance. All data stays local in your browser — nothing is sent to external servers.
Permissions explained:
- Storage: Save your override rules locally
- DeclarativeNetRequest: Intercept and redirect network requests
- Tabs: Detect the active tab's URL for rule matching
- Host permissions: Apply overrides on any website you choose
Key Features:
- Override JavaScript, CSS, HTML, and API responses on any website
- Redirect requests to local or remote files
- Modify HTTP response headers
- Block unwanted requests
- Inject custom JavaScript and CSS into any page
- Group rules by project with enable/disable toggles
- URL matching with contains, equals, wildcard, and regex patterns
- Domain and resource type filtering
- Import/export rule configurations
- Full editor UI for managing complex rule sets
Use Cases:
- Debug production issues safely without pushing code changes
- Test JavaScript fixes before deploying to a live environment
- Mock API responses for frontend development
- Block analytics or tracking scripts during testing
- Override CSS to prototype design changes in real-time
How It Works:
Create override rules that match URLs by pattern. When a matching request is detected, Live Resource Override intercepts it and applies your modification — whether that's replacing the response body, redirecting to a different file, injecting code, or modifying headers. All changes are session-only and never touch your production environment.
Built with Manifest V3 for security and performance. All data stays local in your browser — nothing is sent to external servers.
Permissions explained:
- Storage: Save your override rules locally
- DeclarativeNetRequest: Intercept and redirect network requests
- Tabs: Detect the active tab's URL for rule matching
- Host permissions: Apply overrides on any website you choose
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Permissions and data
Required permissions:
- Block content on any page
- Read your browsing history
- Access browser tabs
- Access your data for all websites
Optional permissions:
- Access your data for all websites
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 1.0.0
- Size
- 45.9 KB
- Last updated
- 13 days ago (Mar 30, 2026)
- Related Categories
- License
- MIT License
- Privacy Policy
- Read the privacy policy for this add-on
- Version History
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