Sigma

What is Sigma?

Sigma, listed in app stores as Sigma AI Browser, is a desktop and mobile web browser that its maker positions as an AI-first agentic browser combining an AI agent, deep research and other AI tools for navigating, creating and automating on the web. It is built on the Chromium engine, which the company says it then extended with its own features.

The browser is published by SigmaBrowser OÜ, a limited liability company registered in Tallinn, Estonia. Sigma took its current shape in July 2025, when Bagoodex and Sigma announced a merger into a single product ecosystem under the Sigma Browser brand. The site menu also places Sigma inside an "Ecosystem" of Atomic-branded products, including Atomic VPN, Atomic Chat, Atomic Mail and Atomic Wallet.

Two points matter first: browsing is free but cloud AI features follow Free, Plus and Pro quotas, and the agent needs either your own API key or a local model in Private Mode.

Core features

AI agent

• Acts on websites: The agent lets you use the OpenClaw and Hermes agent options inside the browser, and it can navigate pages, click, type, read web content and help complete tasks across websites.
• Release status: The agent arrived on Windows as an "Autonomous AI Agent (Beta)" in the October 25, 2025 release, and a February 3, 2026 update listed a smarter agent framework for Windows and Mac.

AI Chat and Deep Research

• Chat modes: Sigma AI Chat bundles Text Writer, which generates, edits, rewrites and improves text, alongside Web Search, Chat With Page, image generation and TG Search, which searches Telegram posts and returns a summarized view of opinions.
• Deep Research: Deep Research works inside AI Chat; it searches across sources, reads key information and turns the results into organized answers.
• Mobile extras: The November 29, 2025 iOS and Android release added AI Chat on mobile, Deep Research mode, voice input for prompts and export of AI responses.

Eclipse and local models

• On-device LLM: Sigma runs Eclipse, a local LLM built into the browser, and the company says your data stays on your device with no cloud processing and no prompts sent to servers.
• Setup: Local AI models can be downloaded right in the browser, or you can connect your own via API key; the company puts local setup at about a minute.
• Mixing local and cloud: You can switch between local AI models and cloud models at any time, keeping everyday or sensitive tasks local and calling a cloud model when you need more reasoning power.
• Launch: Sigma announced Eclipse on January 6, 2026, describing it as a fully local, cloudless large language model architecture.

That makes Sigma a local AI browser, and its "Uncensored AI" chat mode is set up the same way, by downloading and activating a local model in settings.

Image generation

• Text to image: The image generator turns text prompts into visuals, with styles that range from realistic and cinematic to anime, comic, 3D and pixel art, and it can restyle existing images.
• Image to video: A finished image can be turned into a video; Free users get limited image-to-video generations and paid plans get higher limits, although the same FAQ also says animation availability may depend on your plan, account and app version.

Browser tools

• Ad blocking: A built-in ad blocker removes intrusive ads for a cleaner page.
• Quick Translate: You can highlight any sentence on a page and translate it into another language.
• Extensions: Browser extensions can be added and managed as in other modern browsers.
• Import and sync: AI Chat syncs across devices, and bookmarks, passwords and history can be imported from Chrome, Edge or Firefox in a couple of clicks.

Speed and memory claims

Sigma publishes its own benchmark results rather than independent ones. In vendor tests with Speedometer 3.0, run 10 times per browser on a MacBook Pro M4, Sigma reports scores 1.13x faster than Chrome, 1.17x faster than Brave and 1.30x faster than Safari. A second vendor test with 10 identical tabs open lists Sigma at 0.8 GB of RAM against 1.00 GB for Chrome.

Guide

Setting up the agent takes three steps on desktop:

1. Open Sigma and select Agent from the start page or the toolbar.
2. Choose OpenClaw or Hermes in Settings, then connect an API key or select a local model in Private Mode.
3. Ask the agent to work through website steps, review content, handle files or complete other browser tasks.

Running a research request follows the AI Chat flow:

1. Open the AI Chat panel in the browser.
2. Select Deep Research mode before typing your question.
3. Enter a topic or question and wait for the structured answer.

For private sessions on a Mac, the Private Mode toggle in the toolbar opens a private browsing window with tracker protection and ad blocking already on, and switching the toggle off returns you to normal browsing.

Sigma use cases and examples

The vendor's own examples show where each tool is meant to fit:

• Repetitive web chores: The agent is pitched for tasks from booking tickets to cleaning up an inbox, paying bills, posting on social media or updating spreadsheets.
• Structured research: Deep Research can queue sources, cluster information and produce structured insights for market analysis, academic review or a deep dive into a topic.
• Content visuals: The image generator is aimed at visuals for blog posts, social media, websites, presentations and marketing campaigns.
• Confidential documents: With a local model, you can review contracts, reports and personal files and extract key details without those files leaving your machine.

These are the company's descriptions of intended use, not measured success rates.

Who is it for

Sigma fits people who want AI tools inside the browser rather than in a separate tab or app.

• Researchers and content workers: Sigma names students, marketers, researchers, writers and founders among the people Deep Research is useful for.
• Privacy-sensitive professionals: Eclipse is presented as suited to sensitive work such as legal and corporate documents, medical data, R&D, finance and cybersecurity, where keeping prompts on the device matters.
• Web3 users: The browser can connect to decentralized apps, manage wallets and interact with blockchain networks directly.

It is a weaker fit for Linux users, since Linux packages are still listed as coming soon, for owners of Intel-based Macs, since the download page lists only an Apple Silicon build, and for anyone who wants an agent that works without either an API key or a local model.

Platforms

Sigma's download page lists the following builds:

Android availability is inconsistent across Sigma's own pages. The download page header says Sigma is available on macOS, Windows, iOS and Android while the Android rows say coming soon. The homepage, meanwhile, invites visitors to join an Android waitlist. As captured on October 5, 2026, the Android store listing showed 3.6 stars from 194 reviews, an Everyone rating and 10K+ downloads.

Sigma AI Chat can also be used in a web app without installing the browser, where you continue with Google or Apple to create or access a profile. Inside the browser, accounts can be created by signing in with Google, Apple or a seed phrase. The App Store record names SigmaBrowser OÜ as the developer and carries an "Unrestricted Web Access" advisory.

Pricing

The plan page lists three tiers, with an annual toggle that shows a -20% price:

The Plus multipliers are relative to Free, but the plan page describes Free allowances only as "limited" without publishing the base numbers, and it shows per-month figures without an annual total.

Several Sigma pages describe pricing differently. The AI browser page calls Sigma a free AI browser with no subscriptions. The Mac page says Sigma is completely free for macOS, including the AI agent, AI chat, deep research and local AI. Both statements sit alongside the paid tiers above.

Local models are the one area with no metering: local AI in Sigma is described as completely free, with no API fees, subscriptions or usage limits, and the only real cost being disk space for the model file and some RAM while it runs.

A newsletter pop-up on the site offers 50% off the first subscription purchase with the promo code SIGMA50, which must be entered in a special field at Stripe checkout. The Terms of Use say only that applicable fees are displayed on the site or in the apps, and no refund or cancellation terms were found in the terms and privacy policy checked for this page.

Sigma alternatives

Sigma's own comparison pages set it against ChatGPT Atlas, Perplexity Comet, Chrome, Safari and Brave. Two browsers with verified current terms make useful contrasts:

Brave with Leo is closer for private chat without signing in; Opera Neon suits buyers who want hosted agents on one paid plan instead of supplying an API key.

Limitations

The main boundaries come from Sigma's own pages and terms:

• Agent needs your key or a local model: In standard browsing you need to connect an API key to use agents like OpenClaw or Hermes; only Private Mode can use local models instead.
• Local models trade off power: Sigma itself says the largest cloud models are still stronger on complex reasoning, long documents and specialized coding work.
• Local storage footprint: The Eclipse desktop project linked from the homepage downloads llama.cpp and a default model of about 3-6 GB during setup.
• Private Mode is not anonymity: Sigma states that Private Mode reduces local traces but does not make you completely anonymous, and your internet provider, employer or websites may still see some activity.
• Inconsistent model names: The local AI page names Hermes and OpenClaw as models you can run locally. The Windows page instead names Qwen and Gemma.
• Open-source wording versus terms: The homepage says the browser code is public. The Terms of Use, however, prohibit modifying, copying, reverse engineering or decompiling any portion of the Services. The repository linked from the homepage is the Sigma Eclipse LLM project, licensed under the PolyForm Noncommercial License 1.0.0, which its README summarizes as free for personal, educational and non-commercial use, with commercial licensing by contact.
• Location masking is barred: The terms ask users not to disguise their location through IP proxying or other methods, which matters for anyone planning to pair the browser with a VPN.
• Disputes go to Estonia: The agreement is governed by Estonian law, with binding arbitration at the Arbitration Court of the Estonian Chamber of Commerce and Industry in Tallinn and a waiver of class actions.
• Services can change: Sigma may modify or discontinue any portion of its services at any time, with or without prior notice.
• Third-party services: Integrated third-party services run under their own terms, and Sigma says it is not responsible for your use of them.

Privacy and data handling

Sigma's privacy statements are vendor claims, and the formal privacy policy is short:

• Encryption claims: The homepage says all user data and AI chat conversations are end-to-end encrypted, and its FAQ adds that Sigma never stores credentials or task data after execution.
• Local model data: Prompts, page content and documents processed by a local model are described as never leaving the device, not being logged and not being used for training. The privacy policy checked does not address whether cloud AI prompts are used for model training.
• Regulation: Sigma says it complies with GDPR and CCPA.
• Your rights: The privacy policy lists rights to know, access, correct, transfer, restrict processing of and delete personal data, but Sigma may decline requests where it must keep transaction records by law or for antifraud and security reasons.
• Cookies: Sigma's websites use cookies for sessions and settings and may use third-party cookies for visitor statistics and marketing measurement.
• Store declaration: In the Android store's data safety section, the developer declares no data collected and no data shared with third parties.
• Private profiles: Separate work and personal profiles are encrypted and secured by a 12-word phrase. On iPhone, private mode searches with DuckDuckGo by default.
• Children: The services are not directed to children under 13, and the terms require users to be of legal age in their country of residence.

For a private AI browser, the split matters: on-device tasks stay local, while cloud and API-key tasks rely on Sigma's encryption statements and your model provider's terms.

FAQ

Q1. Is Sigma free to use?

The browser, the Free plan and local models cost nothing; heavier cloud AI use requires the paid Plus or Pro tier.

Q2. Does the Sigma AI browser agent need my own API key?

In standard browsing, yes; in Private Mode it can use a local model instead.

Q3. Can Sigma run AI without an internet connection?

Yes, with a local model. Sigma says a downloaded local model can answer questions, summarize pages and draft text on the device, and that it keeps working offline.

Q4. Is Sigma available on Android and Linux?

Linux builds are listed as coming soon. Android is inconsistent: Sigma's download page lists Android as coming soon, while an Android store listing from SigmaBrowser OÜ is already live.

Q5. Who makes Sigma?

SigmaBrowser OÜ of Tallinn, Estonia, which is also the developer named on the iPhone and Android store listings.