Create userscripts-api.md

docs/adguard-browser-extension/user-scripts-api.md

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+---
+title: User Scripts API
+sidebar_position: 8
+---
+
+:::info
+
+This article is about AdGuard Browser Extension, which safeguards only your browser. To protect your entire device, [download the AdGuard app](https://adguard.com/download.html?auto=true).
+
+:::
+
+When adding a custom filter or user rule, a notification will appear asking you to enable the Developer mode to use these features in the extension.
+
+![Notification *border](https://cdn.adtidy.org/content/Kb/ad_blocker/browser_extension/notification-allow-user-scripts.jpg)
+
+Starting with version 5.2, AdGuard Browser Extension uses the User Scripts API. Chrome requires this new API to follow best practices for user safety.
+
+## What is the User Scripts API?
+
+The User Scripts API is a tool that allows extensions to run customized JavaScript scripts on webpages. These are often used to modify or enhance websites in ways that aren’t originally provided by the website itself.
+
+With the shift to Chrome’s Manifest V3, many older methods of injecting scripts are limited or delayed. However, there is an exception for the User Scripts API.
+
+Learn more about the impacts of the MV3 policies in our [blog post](https://adguard.com/en/blog/review-issues-in-chrome-web-store.html).
+
+## How to enable the Developer mode
+
+To use custom filters and JavaScript rules in the *User Rules* tab, you must set up your browser first. This will give the extension a reliable and secure method of injecting scripts into webpages at the optimal time. Follow the instructions below depending on your Chrome version.
+
+### For Chrome versions prior to 138
+
+You must enable Developer mode for extensions. To do so, open the Chrome menu by clicking the three dots in the upper-right corner, go to *Extensions* ⭢ *Manage extensions*, and toggle the *Developer mode* switch.
+
+![Manage Extensions *border](https://cdn.adtidy.org/content/Kb/ad_blocker/browser_extension/developer-mode-enable1.jpg)
+
+### For Chrome version 138 and later
+
+You must enable the *Allow user scripts* toggle. To do so, open the Chrome menu by clicking the three dots in the upper-right corner, go to *Extensions* ⭢ *Manage extensions*, and toggle the *Allow user scripts* switch.
+
+![Manage Extensions *border](https://cdn.adtidy.org/content/Kb/ad_blocker/browser_extension/allow-user-scripts1.jpg)