Best AI assistant extensions

This is OpenAI's official Chrome extension, and the natural first try if you already use ChatGPT. A side panel puts your normal ChatGPT beside the page you are reading, so you can ask about the tab in front of you. The ChatGPT desktop and web apps can also use your browser to work in your tabs, such as research on logged-in sites and data entry, without taking over your window.

OpenAI's documentation says ChatGPT asks before it uses each new website: allow once, allow for that site, allow for all sites or decline. It asks every time it wants your browser history. OpenAI says it keeps browsing data only when it becomes part of the chat, such as page text, screenshots or tool calls.

The catch is trust. The Chrome Web Store rating is a low 2.7 from about 1,100 ratings, so read recent reviews first. A consumer account may have chats used to improve OpenAI's models unless you turn off "Improve the model for everyone", and OpenAI's own docs say malicious page content can make ChatGPT copy data to the wrong place. Keep secrets out of browser tasks. We could not confirm which plans include it. It suits people already in ChatGPT who accept broad access.

Claude in Chrome is Anthropic's browser agent. A side panel lets you describe a task, and Claude reads the page, clicks, types, navigates and fills forms while you watch. Anthropic pitches it at work behind a login with no export button, such as pulling figures from vendor portals, and data entry.

Its safety guidance is the plainest of the official options. Anthropic calls prompt injection the main risk and says the risk "is not zero". It describes two classifiers that screen content and actions, a mode that asks before acting one site at a time, and an "automatically approve" mode with a separate safety check. In internal testing it reports attack success below 0.08 percent, and says that is no guarantee.

The catch is the data and the access. Claude takes screenshots of the active tab and cannot filter sensitive content out, so anything visible joins the conversation. Consumer chats may be used to improve Claude only if you allow it or a chat is flagged for safety review. Where an organisation enables HIPAA it is off by default and outside the business associate agreement. It needs a paid plan, runs only in Chrome and is in beta. Use a separate profile without sensitive accounts, as Anthropic recommends.

Page Assist is a sidebar and web interface for AI models you run yourself, and it is the only good option here for Firefox. You bring your own model, usually through Ollama, so setup takes effort and quality depends on your hardware. If you want the page and your questions to stay off other companies' servers, this is the one.

It connects to Ollama, to any OpenAI-compatible endpoint such as LM Studio or llama.cpp, and in beta to Chrome's built-in Gemini Nano. In the sidebar you can chat about the current page, add PDFs and documents, use vision models and run web search. Newer beta features include tab mentions, an MCP client and memory. The README says chat history and settings are stored locally in the browser.

The Chrome Web Store listing says the developer will not collect or use your data, and the MIT-licensed code is public, so you can check. Point it at a cloud endpoint and that traffic goes where you send it. You need a computer able to run a model. It is one developer's project, though it has about 8,000 GitHub stars. The README also carries an affiliate-tagged sponsor link to a model-routing service; we saw that in the README, not in the extension.

Sider is the most polished third-party sidebar, with by far the largest audience: about 5 million users and a 4.9 average from about 115,000 ratings on the Chrome Web Store. It comes from Vidline Inc. and puts ChatGPT, Claude, Gemini, DeepSeek, Grok and others in one panel. It is the pick if you want to compare models from several makers in one place.

Group chat is the main draw: you ask several models at once and compare their answers. It also handles page chat, PDF chat, YouTube and article summaries, translation and a right-click menu for explaining or rewriting selected text. It is kept up to date, with version 5.35.3 released on 21 October 2026.

The trade-off is that Sider sits between you and the model makers. Its privacy policy says content needed for a request is sent through Sider's servers to the AI provider behind your chosen model. We could only read excerpts of the policy, so we have not confirmed what it says about training or retention. It asks for access to all sites and the cookies permission, and it is closed source. Treat it as a convenience tool for non-sensitive pages, and use a model maker's own extension for private work.

HARPA AI is less a chat window than a toolbox for repeat web work. It comes from HARPA AI Technologies Oy of Espoo, Finland. The sidebar offers summaries and over 100 page-aware commands, monitors that watch a page for price or stock changes, data extraction to CSV or JSON, and webhook triggers for Zapier, Make and n8n.

Its privacy policy is one of the clearer ones among the third-party options. It says HARPA does not collect or store your browsing data on its servers, and that page data is processed locally and sent to a language model provider of your choice. It says page content is read only when you allow it, for example in page-aware mode (off by default) or through a scheduled monitor. It does not say whether data is used to train models.

The power comes with real access. It asks for all sites and permissions such as cookies, browsing data and notifications, scheduled commands run in the background so a mistake can repeat, and the code is closed. HARPA's own pages describe subscription and lifetime options with no trial and no refunds, so read the terms first. It suits people who want to automate and monitor pages, not casual chat.