Sigma Browser AI Chat Review 2026
Quick verdict
Research verdict
Interesting for local-first browsing, but verify the agent and cloud path yourself
Sigma is unusual because it markets both an on-device model and browser automation in one product. Eclipse may suit offline summaries and drafts; Deep Research, image generation and agent actions have different processing and risk profiles. The Free plan is the right place to validate extension compatibility, page handling and privacy settings before paying.
What Sigma currently offers
Eclipse local AI
Sigma says Eclipse processes prompts and history on-device and can work offline. Treat this as a vendor claim until network activity and local storage are independently inspected on the current build.
AI Chat and Chat With Page
The product page lists page analysis, writing, web search, deep research and image generation. Check citations and do not assume a page summary is factually complete.
AI Agent
The agent is designed to navigate, fill fields and perform browser tasks. Use a low-risk test account first and require confirmation before submissions, payments or irreversible actions.
Browser controls
Sigma advertises an ad blocker, privacy protections and a mnemonic profile. A recovery phrase is a high-value secret: store it offline and never paste it into chat or support forms.
Privacy: local does not mean every feature is local
The Eclipse page says the local model runs without cloud processing. Sigma’s main product page also describes encrypted in-transit processing for agent tasks and says credentials or task data are not stored after execution. Those claims describe different paths. Before using legal, medical, financial or client data, confirm the selected feature, inspect its permissions and review the current privacy policy.
Which plan makes sense?
| Plan | Current price | Best use | Main caution |
|---|---|---|---|
| Free | $0 | Compatibility and privacy evaluation | Cloud and agent limits are not numerically clear for every task |
| Plus | $8 annual-equivalent / $10 monthly | Frequent writing, search and occasional agent use | “x more” limits depend on an unstated Free baseline |
| Pro | $60 annual-equivalent / $75 monthly | Heavy agent and research use after a measured trial | High price without an independent success-rate benchmark |
A reproducible test before switching browsers
- Record the exact Sigma build, OS, device, RAM and plan.
- Use five fixed tasks: offline summary, cited research, form fill, file analysis and a JavaScript-heavy site.
- Capture screen video, completion time, wrong actions, confirmations and network state.
- Repeat the same tasks in your current browser with the same extensions disabled.
- Keep recovery phrases, passwords, payment data and private client files out of the test.
A future scored verdict should publish those raw artifacts. Until then, the product is worth a controlled Free-plan trial, not a 4.5/5 evidence-backed rating.
Frequently asked questions
Is Sigma Browser free?
Yes. The official pricing page lists a $0 Free plan with limited cloud and agent features.
Is every Sigma AI feature local?
No. Sigma describes Eclipse as local/offline, while its broader chat, research, image and agent features have different processing requirements. Check the active mode.
Is Sigma faster than Chrome?
This review does not make that claim. It has no current reproducible benchmark file for Sigma and Chrome on identical hardware.
Should I pay for Plus?
Only after the Free plan completes your real tasks reliably and you can identify which limits Plus actually removes.