The browser is where most knowledge work actually happens. Email drafts, research, documentation, code review, support tickets, social posts, all of it sits inside a tab. Pasting that work into a separate ChatGPT or Claude window costs real time, breaks the flow, and leaks context the model could have used. That is what made AI Chrome extensions interesting in the first place, and that is why so many of the standalone AI editor projects ended up shipping as Chrome extensions instead.
The eight best apps for AI Chrome extensions below were picked from real daily use. Some are free, some are subscription, all of them work in the latest Chrome and Edge builds. The list skews toward extensions that summarize, write, search, or code right inside the page rather than pop-out chat boxes you have to copy out of.
What to look for in an AI Chrome extension
A few criteria separate the useful tools from the noisy ones:
- Page context. The extension should send the current tab’s content to the model so answers are grounded in what is on screen.
- Selection actions. Right-click or hotkey to summarize, rewrite, translate, or explain a highlighted block.
- Model choice. Multi-model tools let you swap between GPT, Claude, Gemini, and open-weight backends depending on the task.
- Privacy controls. Local mode, no-log policies, and a clear list of what the extension reads from each page.
- Coding support. If you live in GitHub or your CI dashboards, an extension that reads diffs and suggests fixes earns its slot.
- Free tier limits. How many messages per day, which models, and whether the free tier is genuinely usable or just a trial.
Quick comparison
| Extension | Best for | Free plan | Starting price/mo | Standout |
|---|---|---|---|---|
| Monica AI | All-in-one chat + writing | 40 queries/day | Around $9.90 | Multi-model switcher, sidebar persists across tabs |
| Claude for Chrome | Long-context reading | Yes, with Claude account | Around $20 (Claude Pro) | Direct access to Claude Sonnet 4 inside any page |
| Perplexity Companion | Research and citations | Yes, generous | Around $20 (Pro) | Live web search with sources in the answer |
| Merlin AI | Writing and YouTube summaries | 102 queries/day | Around $14.25 | Strong summarization across video transcripts |
| HARPA AI | Web automation | Free tier with caps | Around $9 | Scripted page actions and scraping recipes |
| Sider | Sidebar chat with vision | 15 queries/day | Around $9.90 | Image upload and OCR in the side panel |
| ChatGPT for Google | Quick answers next to search | Yes | Around $8 (some features) | Compares model answers next to Google results |
| Grammarly | Editing and tone | Yes | Around $12 | The most reliable real-time grammar coach |
The extensions
1. Monica AI, the best all-rounder
Monica AI installs a sidebar that follows you between tabs, holds a single chat history, and lets you flip between GPT-4, Claude, Gemini, and a handful of open-weight models without opening a separate dashboard. Highlight text and you get summarize, translate, rephrase, explain, and reply actions right where you are. The free tier covers casual use, and the writing-heavy paid tier is one of the cheaper multi-model tools on the market.
Where it falls short: the free quota resets daily and a long research session can burn through it fast. Some advanced features require the Pro plan.
Pricing: Free with daily query cap. Pro plans start around $9.90 per month billed annually, with higher tiers for image generation and team features.
Platforms: Chrome, Edge, Firefox, Safari extensions plus iOS, Android, and a web app.
Download: Chrome Web Store, Monica.im
Bottom line: If you only install one AI extension, make it this one. The model switcher alone pays back the sidebar real estate.
2. Claude for Chrome, the long-context heavyweight
Anthropic’s official Chrome extension drops the Claude assistant into a side panel that can read the whole page, even very long ones. The 200K context window means a single PDF, research paper, or long thread fits without chunking. Highlight text to ask follow-ups, or use the slash menu for summarize, fact-check, and rewrite.
Where it falls short: free use is tied to a Claude account with a smaller daily allowance, and the extension is best with a Claude Pro subscription. There is no built-in web search.
Pricing: Free with a Claude account, Pro plan around $20 per month for higher limits and the latest models.
Platforms: Chrome, Edge, plus the Claude desktop and mobile apps.
Download: Chrome Web Store, Claude.com
Bottom line: Pick this if your day is reading long things and asking questions about them. The reasoning quality on tricky prompts is consistently the strongest in this list.
3. Perplexity Companion, the research extension
Perplexity Companion turns every page into a research surface. The sidebar runs live web searches alongside the LLM answer, cites the sources inline, and keeps a session history that you can revisit weeks later. It is the only extension here that consistently surfaces footnotes good enough to drop into a brief without rechecking every link.
Where it falls short: it pushes you into the Perplexity ecosystem for follow-ups and the citations are not always the freshest source.
Pricing: Free tier covers most casual use. Pro is around $20 per month and unlocks Claude, GPT-4, and file uploads.
Platforms: Chrome, Edge, Arc plus Perplexity desktop apps and a strong web app.
Download: Chrome Web Store, Perplexity.ai
Bottom line: Anyone whose work involves citing sources should keep this pinned. It is the cleanest path from question to footnote in a browser today.
4. Merlin AI, the YouTube summarizer
Merlin earned its slot for one feature: a transcript-aware summary panel that opens next to any YouTube video and lets you ask questions about what was said. It also handles webpage summaries, Gmail drafts, and rewrites inside Docs, but the video work is the standout.
Where it falls short: the free tier caps queries by day rather than by token, so a couple of long videos can exhaust it. The sidebar UI feels busier than Monica or Sider.
Pricing: Free tier of 102 queries per day. Paid plans start around $14.25 per month billed annually.
Platforms: Chrome, Edge, plus a web app.
Download: Chrome Web Store, GetMerlin.in
Bottom line: Worth installing alongside Monica if you watch a lot of long-form video or work in a Google Workspace heavy team.
5. HARPA AI, the automation power tool
HARPA blurs the line between extension and RPA. You can write or download scripted page actions that fill forms, monitor product pages for price changes, summarize email threads, and trigger LLM follow-ups based on what the page contains. The community library has hundreds of pre-made recipes for common SaaS workflows.
Where it falls short: the learning curve is the steepest in this list, and the UI is dense. Some scripts behave inconsistently across sites that change layouts often.
Pricing: Free tier with caps on automated actions. Paid plans start around $9 per month.
Platforms: Chrome, Edge, Brave.
Download: Chrome Web Store, HARPA.ai
Bottom line: Pick this if you want browser automation that does not require a Zapier subscription. Casual users will find the depth overwhelming.
6. Sider, the side-panel multitool
Sider sits in the same all-in-one bucket as Monica but leans harder into image work. Drop a screenshot into the panel and it will OCR the text, describe the image, or summarize a chart. Multi-model switching is included, and the free tier is one of the more usable starter quotas.
Where it falls short: the 15-query free daily cap is small if you upload images often. Some advanced models are paywalled.
Pricing: Free with a 15-query daily cap. Paid plans start around $9.90 per month billed annually.
Platforms: Chrome, Edge, Safari, Firefox plus desktop and mobile apps.
Download: Chrome Web Store, Sider.ai
Bottom line: A solid Monica alternative for anyone who works with screenshots, dashboards, or OCR on the daily.
7. ChatGPT for Google, the answer-comparison extension
This extension drops a ChatGPT answer panel next to your Google, Bing, or DuckDuckGo results, so you can compare an LLM response with the actual search index in one glance. It supports Claude, Gemini, and Llama models alongside the default OpenAI backend, and it stays out of the way when you are not searching.
Where it falls short: it does not do much outside the search pages. There is no broader page chat or selection actions, which limits how much it earns its slot.
Pricing: Free, with Premium starting around $8 per month for unlimited messages and pro models.
Platforms: Chrome, Edge, Firefox, Brave.
Download: Chrome Web Store, ChatGPT4Google.com
Bottom line: A focused tool, not a do-everything sidebar. Install it if your day is mostly research-style searching.
8. Grammarly, the editor that earned its keep
Grammarly is the oldest entrant on this list and it still beats every general-purpose AI tool at tone, clarity, and inline editing in long documents. The AI features now include rewrites, tone shifts, citation lookups, and full drafts, but the core grammar work is what keeps it on the install list.
Where it falls short: it nudges aggressively toward the paid tier, and some users find the rewrite suggestions over-formal. It also adds a small performance overhead in heavy text editors.
Pricing: Free for basic grammar. Premium starts around $12 per month billed annually.
Platforms: Chrome, Edge, Firefox, Safari plus desktop apps for Windows and macOS.
Download: Chrome Web Store, Grammarly.com
Bottom line: Keep this on for any role where written tone matters. The general-purpose LLM tools above will not replace it for editing long-form work.
How to pick the right one
- If you want a single sidebar that covers writing, research, and chat, pick Monica AI.
- If you read long PDFs and threads daily, pick Claude for Chrome.
- If your work needs cited sources, pick Perplexity Companion.
- If you summarize a lot of video, pick Merlin AI.
- If you want browser automation built in, pick HARPA AI.
- If image and screenshot OCR matters, pick Sider.
- If you mostly want better search results, pick ChatGPT for Google.
- If you write long documents and tone matters, pick Grammarly.
Most teams end up with two installed: a primary sidebar like Monica or Claude for Chrome, plus Grammarly for the editing pass. Stacking three or more usually creates conflicting hotkeys and slows the browser down.
FAQ
What is the best free AI Chrome extension?
Monica AI and Perplexity Companion are the two most generous free tiers for everyday use. Monica wins for chat and writing variety, Perplexity wins for research with citations. Try both for a week and keep whichever fits your workflow better.
Are AI Chrome extensions safe to use?
The mainstream extensions in this list ship from established companies and request the page-content permission for legitimate reasons. Still, install only from the official Chrome Web Store listing, read the privacy policy, and avoid sideloaded copies. Disable any extension that requests permissions it does not need for the features you actually use.
Can I run AI Chrome extensions on Edge or Firefox?
Most of the top extensions support Edge, and several support Firefox and Safari. Monica, Sider, Merlin, and Grammarly all have multi-browser builds. Claude for Chrome is currently Chromium-focused. Check the official site, not just the Web Store, before assuming compatibility.
Will an AI extension slow down my browser?
A single extension adds negligible overhead. Running three or four AI sidebars at once is what causes the noticeable slowdown, since each one injects scripts into every page. Pin one primary tool and one specialist, and disable the rest.
