JS Mage > Inject Custom JavaScript Into Any Website, iFrames, Import/Export

by Jovan Ralić · saasminded.dev · Developer Tools

Established publisherManifest V3 Free

View in Chrome Web Store Data as of 16 Oct 2026

Advanced custom JavaScript injector with native CSP bypass.

Users

−1 in 30 days

Rating

1.0 / 5

+1.00 in 30 days

Ratings

+1 in 30 days

Store rank

#163K

#136K among extensions

Version

1.3.1

updated 27 Jun 2026

Users

monthly, 7 months

Latest, 16 Oct 2026: 16 usersMove the mouse over the chart for any month

Ratings count

monthly, 7 months

Latest, 16 Oct 2026: 1 ratingsMove the mouse over the chart for any month

The Chrome Web Store rounds user counts down to the leading digit, so the user line moves in steps. The ratings count is exact and is the better signal of real adoption.

About JS Mage > Inject Custom JavaScript Into Any Website, iFrames, Import/Export

JS Mage is a utility for injecting custom JavaScript directly into the MAIN execution world of web pages. It natively bypasses standard extension isolation and Content Security Policy (CSP) restrictions that normally block inline script execution. This allows your injected code to interact directly with the host page's window object, native variables, and frameworks. The extension uses a draggable, resizable code editor injected into the active tab via a Shadow DOM, preventing the host page's CSS from breaking the editor's UI. Core Features ● Execution Scopes: Maintain independent scripts for specific hostnames (Local) or a single script applied across all websites (Global). ● Execution Modes: Run code manually on demand, or toggle "On Load" to automatically inject the script as soon as the DOM finishes loading. ● In-Page Editor: A floating, resizeable editor overlay with adjustable opacity. Includes a custom regex-based syntax highlighter, a built-in code formatter, and an independent undo/redo history stack. ● Theming: 13 built-in syntax highlighting themes, including standard IDE defaults (Dark+, Monokai, Dracula, Nord, One Dark). ● State & Backup: Export individual scripts as .js files, or dump/restore your entire cross-site storage database via JSON. ● Kill Switch: A master power toggle to instantly disable all script injections without losing your saved code. Controls & Shortcuts ● Click Extension Icon: Toggle the editor UI. ● Double-Click Extension Icon: Toggle master power (Enable/Disable all injections). ● Ctrl/Cmd + Shift + Space: Global shortcut to toggle the editor visibility. ● Ctrl/Cmd + Enter: Execute the current script immediately. ● Ctrl/Cmd + /: Toggle line or block comments. ● Ctrl/Cmd + Z / Shift + Z / Y: Native-style undo and redo. Note: Because scripts execute in the MAIN world context, disabling the extension's power or removing an auto-run script requires a page refresh to clear previously executed code from the browser's memory.