Extensions and User Scripts

Use an Extension when you need a packaged browser integration with its own permissions and lifecycle. Use a User Script for page-specific automation/customization that can be expressed as script code and match rules.

• Install only from trusted sources.
• Enable/disable without deleting when testing.
• Review permissions and compatibility.
• Use the independent app/extension updater for signed compatible package updates.

• Create, edit, import or paste script code.
• Keep match rules narrow.
• Use grants only when required.
• Test in a controlled Profile before broader use.
• Keep scripts scoped to the pages and capabilities they actually need, especially when a script can access Profile or browser data.

• Disable the extension/script and reload.
• Check target URL and permissions.
• Copy exact errors/logs.
• Re-enable one component at a time.