Usermods

Usermods is an open-source browser extension that customizes websites by chatting with any LLM.

Usermods is an open-source browser extension that lets you customize any website by chatting with an LLM. You open the side panel on any page, describe the change you want, and the extension inspects the page, writes a userscript, tests it live, and provides Try and Save buttons. It supports Anthropic, OpenAI, OpenRouter, local models via Ollama or LM Studio, and chat subscriptions like ChatGPT and SuperGrok. The model reads a pruned DOM, takes screenshots, and runs scripts to test its work before proposing changes. You can import your Tampermonkey library, edit installed mods in chat, and export standard user.js files.

Usermods at a glance

Best for: Software engineer
Runs on: Chrome extension, Safari, macOS, iOS
Pricing: Free and open source under the MIT license.
Released: October 2026
Category: AI coding tool
Website: github.com/kballenegger/usermods

Key features

Chat that inspects the page and writes a mod
Support for multiple providers and chat subscriptions
Edit any installed mod directly in chat
Tampermonkey import and GM API compatibility
Image and screenshot support in the composer
Drafts with versions and line diffs
Dashboard for all chats and mods across sites

Use it for

Customize any website appearance or behavior by chatting with an AI
Migrate existing Tampermonkey userscript libraries
Run one-off tasks like extracting data or images from a page
Edit installed userscripts using natural language

Alternatives to Usermods

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