What is the best free alternative to Firefox Smart Window?
Sider is the closest free alternative to Firefox Smart Window: same Browser Extensions & Copilots sub-category, and it is free tier + paid. ChatGPT/Claude/Gemini in a browser sidebar
Best free Firefox Smart Window alternatives
Looking for a free alternative to Firefox Smart Window? Here are 9 browser extensions & copilots worth trying — 9 with a free tier. Firefox Smart Window itself is free.
| Tool | Firefox Smart Window (you searched) | Sider | Monica | Merlin AI |
|---|---|---|---|---|
| Pricing | free | freemium | freemium | freemium |
| Best for | Built-in Firefox AI assistant that answers questions about the page and open tabs and searches browsing history in natural language | ChatGPT/Claude/Gemini in a browser sidebar | All-in-one AI copilot for the browser | Works on any website |
| Visit | Open ↗ | Open ↗ | Open ↗ | Open ↗ |
Firefox Smart Window alternatives — straight answers
Are there free Firefox Smart Window alternatives?
Yes — 9 of the 9 alternatives listed here are free or freemium: Sider, Monica, Merlin AI, MaxAI.me, Opera Browser AI (Aria). None of them are paid-only.
Is Firefox Smart Window free?
Firefox Smart Window is free. There is no paid plan attached to it in the catalog.
How were these Firefox Smart Window alternatives chosen?
They are the other tools in Browser Extensions & Copilots, then the rest of AI Chat & Assistants, ordered free tiers first and capped at 9. There is no sponsorship and no paid placement in that ordering — only the pricing tier decides.
All Firefox Smart Window alternatives
Browse Browser Extensions & Copilots →Sider
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — ChatGPT/Claude/Gemini in a browser sidebar.
- ChatGPT/Claude/Gemini in a browser sidebar
- Summarize any page, PDF or YouTube video
- Translate, rewrite and explain selections
- Works across every website
Monica
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — All-in-one AI copilot for the browser.
- All-in-one AI copilot for the browser
- Access to GPT, Claude & Gemini
- Writing, translation and search tools
- Desktop app and memo features
Merlin AI
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — Works on any website.
- Works on any website
- Summarize YouTube, articles and PDFs
- Multiple frontier models in one place
- Social-media reply generator
MaxAI.me
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — One-click rewrite, reply and summarize.
- One-click rewrite, reply and summarize
- Chat with any page or image
- Instant translation and grammar fixes
- Prompt library built in
Opera Browser AI (Aria)
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — Free, native AI assistant built into Opera's mainstream and GX browsers, no separate app needed.
- Free, native AI assistant built into Opera's mainstream and GX browsers, no separate app needed
- Powered by a mix of OpenAI GPT and Google Gemini models under the hood
- 2025-2026 upgrade added faster models, higher usage limits and access to open-source local models
Page Assist
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — Open-source (MIT) sidebar and ChatGPT-style web UI for local models via Ollama, LM Studio or Chrome's built-in Gemini Nano.
- Open-source (MIT) sidebar and ChatGPT-style web UI for local models via Ollama, LM Studio or Chrome's built-in Gemini Nano
- Chat with the current webpage without sending data to a cloud service
- Works on Chrome, Edge, Brave, Firefox, Vivaldi and Zen; about 8.2k GitHub stars
Gemini in Chrome
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — Gemini side panel that answers questions about the current tab and across tabs.
- Gemini side panel that answers questions about the current tab and across tabs
- Summarizes pages and videos, compares products
- Available on desktop and Android for US users; expanded to Canada, NZ, India and more
- Auto browse agent reserved for paid Google AI plans
Harpa AI
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — AI web automation and monitoring.
- AI web automation and monitoring
- Track prices and page changes
- Scrape and summarize sites
- Custom command workflows
Brave Leo
Browser Extensions & Copilots
✦ WhyA Firefox Smart Window alternative — Built directly into the Brave browser sidebar — no separate site, no account, no signup required for free tier.
- Built directly into the Brave browser sidebar — no separate site, no account, no signup required for free tier
- Access to Claude, Mixtral and Llama models without opening a separate chatbot site
- Conversations never stored on Brave's servers and not used for model training