On January 6, 2019, Opera banned the Tampermonkey extension from being installed through the Chrome Web Store, claiming it had been identified as malicious. This code is inserted after the extension is installed, however the manifest requires the code to be present at installation. The userscripts use code that is created by developers not at Google, and instead is created by third-party developers at places like and Greasyfork. The new manifest would ban remotely accessed code which Tampermonkey is dependent on. In January 2019, Biniok wrote in a Google Groups post that the new Chrome manifest V3 would break the extension. Tampermonkey is one of 33 extensions on the Chrome Web Store to have at least 10 million users. By 2019, Tampermonkey had over 10 million users. In 2011, Tampermonkey was ported to Android, enabling users to use userscripts on Android's internal browser. Eventually the code was re-used and published as a standalone extension for Chrome which had more features than Chrome's native script support. It first emerged as a Greasemonkey userscript that was wrapped to support Google Chrome. Tampermonkey was first created in May 2010 by Jan Biniok.

This software enables the user to add and use userscripts, which are JavaScript programs that can be used to modify web pages. Tampermonkey is a donationware userscript manager that is available as a browser extension.

Savefromnet tampermonkey is it safe