What AI Chrome extensions actually do
An AI Chrome extension puts a language model one click away inside your browser. Instead of copying text into a separate chat tab, you get a sidebar or popup that can read the page you are on, summarise it, rewrite your draft in a text box, answer questions about a PDF or YouTube transcript, and often search the web. The best ones blend into your normal browsing so the AI is available everywhere without breaking your flow. This guide compares the most popular options on the things that actually matter: feature depth, privacy, speed, and value.
The leading extensions compared
Merlin and Monica are the broad all-in-one assistants. Both offer a sidebar chat, page and YouTube summarisation, writing help across the web, and access to multiple models (often GPT, Claude, and Gemini) on a single subscription. They are the “Swiss Army knife” choice — lots of features, occasionally at the cost of a busier interface.
Sider focuses on a clean, fast sidebar with strong page and document reading; it feels lighter and is popular with people who mainly want quick page Q&A and summaries.
Compose AI is narrower and specialises in writing — autocompletion and rewriting in email and text fields — rather than general chat. If your main need is faster typing and better drafts, it does that one job well.
Harpa AI leans toward automation and monitoring: web page actions, price/stock tracking, and workflow-style commands on top of chat and summarisation, which appeals to power users who want the browser to do things, not just answer.
How to judge them
- Feature depth. Do you want one tool for everything (Merlin, Monica), a focused writing helper (Compose AI), a clean reader (Sider), or automation (Harpa)?
- Models offered. Check whether you get GPT, Claude, and Gemini, and whether you can bring your own API key to control cost and data flow.
- Privacy and permissions. Most read every page you visit. Prefer extensions that are transparent about data handling and let you use your own key.
- Speed. A sidebar that lags ruins the convenience; the lighter, well-engineered ones feel instant.
- Value. Free tiers are usually capped; compare the monthly cost against simply using the model providers’ own apps.
Which to choose
If you want a single do-everything assistant, start with Merlin or Monica. If you mostly read and summarise pages, Sider is the cleanest. For writing specifically, Compose AI is purpose-built. For browser automation and monitoring, Harpa stands apart. Whatever you pick, install only well-reviewed extensions from established developers, read the permissions, and favour a bring-your-own-key option when you handle anything sensitive — these tools see everything you browse, so trust is part of the value.