A Firefox alternative built on Chromium
Sigma runs on Chromium, so sites built for Chrome work as expected and Chrome Web Store extensions install in one click. Firefox uses its own Gecko engine and its own add-on store.
Your Chrome extensions and bookmarks keep working
A local AI model built in that works offline
Built-in ad blocker and phishing warnings
Used less RAM than Firefox in our 20-tab test
Why switch from Firefox to Sigma
Firefox is a solid private browser. Sigma adds the built-in AI and Chrome compatibility it doesn't have.
An AI agent in every tab
Describe a goal in plain words and the agent opens pages, clicks and fills forms for you. Check its work before payments and logins. Firefox has no built-in AI agent.
Local AI that stays on your device
Eclipse is a local AI model built into Sigma. It runs on your device and works offline. Firefox's AI sidebar opens third-party cloud chatbots like ChatGPT and Gemini.
Ads blocked, not just trackers
Firefox blocks many trackers but not ads. Sigma blocks ads by default, warns you about phishing sites and keeps Private Profiles secured by a 12-word recovery phrase.
Lighter on memory
In our 20-tab test Sigma used 6.50 GB of RAM and Firefox used 7.00 GB, about 8% more. See our RAM test.
With the same 20 tabs open, Sigma used 6.50 GB of RAM and Firefox used 7.00 GB. Median of 5 runs on an M3 Mac with 16 GB, Sigma's own test.
Sigma
6.50 GB
Firefox
7.00 GB
Private like Firefox, with ads blocked too
Firefox blocks trackers. Sigma blocks ads as well and keeps your AI prompts and profiles on your side. Learn more about Sigma Private Browser
Critical data stays local
With Eclipse your prompts and chat history stay on your device
Eclipse runs on your device and works offline, so nothing you ask is sent to a server. Firefox's chatbot sidebar sends prompts to the provider you pick.
Built-in ad blocker
Ads are blocked out of the box, no extension needed
Sigma blocks ads by default and warns you about phishing sites in real time. Firefox's Enhanced Tracking Protection blocks trackers, not ads.
Private Profiles
Encrypted and secured by a 12-word recovery phrase
Keep work, personal browsing and accounts in separate spaces. Your data is encrypted and secured by a 12-word recovery phrase built on blockchain cryptography.
AI tools built into Sigma
Firefox's sidebar opens third-party chatbots. In Sigma the AI tools live in the browser, and Eclipse runs fully on your device.
AI agent
Tasks done for you
Describe a goal in plain words. Sigma's AI agent opens pages, clicks, fills forms and finishes multi-step tasks for you. Check its work before payments and logins.
Learn more about the AI agentAI chat
Ask. Research. Create
In Sigma you can ask questions, chat with any page, run Deep Research and generate images from a prompt. All of it happens in the same window, with Quick Translate one highlight away.
Learn more about Deep ResearchEclipse
Your own offline AI
Eclipse is a local AI model built into Sigma. It runs on your device, works offline and costs nothing. Ask questions, summarize pages and write drafts while your prompts stay with you.
Learn more about EclipseIs Sigma a better browser than Firefox for you?
If one of these sounds like you, the switch pays off on day one.
You want AI without the cloud
Eclipse answers on your device, even offline. It's a good fit for drafts, notes and questions you'd rather keep to yourself.
You research a lot
Deep Research collects sources and groups the findings. Chat With Page summarizes any article without leaving it.
You rely on Chrome extensions
Sigma installs extensions from the Chrome Web Store, so the tools you use in Chrome work here too.
Replace Firefox with Sigma in three steps
1
Download Sigma
Get the free browser for macOS or Windows, or from the App Store on iPhone. It's a Firefox alternative that runs Chrome extensions.
2
Pick local AI
Choose Eclipse, the local model, when you want prompts to stay on your device. It works without an internet connection.
3
Browse with AI
Ask about any page, translate highlighted text with Quick Translate or hand a task to the agent. When you need sources compared, open Deep Research.
Sigma vs Firefox, feature by feature
What each browser gives you out of the box, checked in October 2026.
Sigma
Firefox
Local AI model built in
Offline AI chat
Built-in ad blocker
Installs Chrome Web Store extensions
AI agent built in
Private Profiles with a recovery phrase
Firefox's AI sidebar connects to third-party cloud chatbots, and Enhanced Tracking Protection blocks trackers rather than ads. Checked in October 2026.
Questions & Answers
If you have any questions,
reach out to us on X at @Sigma_Browser
reach out to us on X at @Sigma_Browser
Is Sigma a good alternative to Firefox?
Do Chrome extensions work in Sigma?
Does Sigma use less RAM than Firefox?
Does Sigma send my AI prompts to a server?
Is Sigma free?
What can I use instead of Firefox?
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Get Sigma on Android
We’ll let you know when Sigma for Android launches.
