Sigma (Private AI Browser)
Chromium-based browser with AI agent (navigates pages, fills forms), chat-with-page, deep research and an in-browser local LLM (Eclipse) for private on-device processing; macOS, Windows, iOS, Android beta.
Active · Verified 2026-10-22 · fresh as of 2026-10-22 · 34 cited facts, 3 with a third-party source · 1 recorded change · Suggest a correction
At a glance
- Type
- Fully-local LLM browser memory vendor fix
- Tier
- T2
- Section
- Browser-agent memory
- Created
- searched not found fix
- Latest release
- not applicable — not OSS fix
- License
- not applicable — not OSS fix
- GitHub
- not applicable — no GitHub repo fix
- Pricing
- Free $0; Plus $10/mo ($8 annual); Pro $75/mo ($60 annual) vendor fix
- Funding
- searched not found — prior $4M SigmaOS seed (2022) belongs to a different company (SigmaOS, YC/San Francisco); Sigma Browser is Sigma Browser OÜ, Tallinn third-party fix
- Freshness
- 2026-10-22 fix
- Layer
- agent-infra repo fix
- Licensing
- commercial vendor fix
- Deployment locus
- computer-use vendor fix
- Compliance
- ccpa, gdpr vendor fix
Memory taxonomy
- storage
- vector
- retrieval
- similarity
- persistence
- long-term
- update
- append-only
- unit
- episode
- governance
- user-controllable
- conflict
- none
When to use
Optimised for: fully-local LLM browser memory
Anti-fit: not for cloud-LLM-required workloads (on-device only)
Pros & cons
Pros
Privacy-positioned browser-as-agent with strong stance on no telemetry / no cross-site memory.
Cons
Newer entrant with small user base; sustainability depends on monetization clarity.
Claims & capabilities
$4.1M raised (YC + LocalGlobe + 8VC + First Round + Khosla). 50k+ users early 2026; 33% MoM growth. Offline AI sessions 3% → 12% Dec 2025-Mar 2026.
Technical surface
- API surface
- not applicable — consumer browser
- Backend storage
- custom (local)
- Deployment
- Managed-only (browser app install)
- Embedding model
- locked
- Multi-tenancy
- not applicable — single-user
- MCP
- searched not found
- A2A
- searched not found
- OpenTelemetry
- searched not found
Alternatives to Sigma (Private AI Browser) → live options ranked by shared design, licence, hosting and MCP support
Similar systems
Other browser-agent memory in the catalog, ranked by inbound references.
- Browserbase T1
Cloud browser infrastructure for AI agents. Headless Chromium sessions with persistent cookies, localStorage, session recording — agent workflows carry state across runs. Memory at the session/automation tier rather than conversational.
- Brave Leo T2
Privacy-focused integrated assistant. Memory is user-curated: explicit facts and preferences persist across all sessions, stored locally with no server retention. Agentic browsing experiment (Brave Nightly Dec 2025) takes multi-step actions inside sites referencing those preferences.
- Dia (Atlassian) T1
The Browser Company's AI-native browser; Atlassian acquired The Browser Company for $610M cash (announced 2025-09, closed 2025-10-21). Stores summaries and preferences locally; opt-in @history feature references up to 7 days of browsing as context. History/chats/bookmarks encrypted local-first.
- Fellou T1
Silicon Valley. Spatial agentic browser with explicit Agentic Memory layer learning from history and notes for instant recall of past research sessions. Operates on logged-in accounts (Quora, X, etc.); runs tasks while user is idle.
- Microsoft Edge Copilot Mode + Journeys (now Copilot in Edge) T1
Copilot Mode retired 2026-05-13; its features now ship as Copilot in Edge. Journeys clusters browsing history into topic cards on the new tab page (desktop, and US mobile); Copilot long-term memory can reference past chats and browsing history with user controls; agentic 'Browse with Copilot' (formerly Copilot Actions) for US Microsoft 365 Premium.
- Opera AI (formerly Aria) T2
Memory feature stores user-declared preferences and facts; injected into future prompts. Understands current tab content; manages open tabs contextually. Memory off by default, end-user controlled, stored alongside the prompt rather than the LLM.
Sources (33 cited facts, 3 third-party)
Each fact links to the page it came from; the badge says who published it (how to read sources).
- What it is Fully-local LLM browser memory vendor
- What it does & what's distinct Chromium-based browser with AI agent (navigates pages, fills forms), chat-with-page, dee… vendor
- Claims / benefits $4.1M raised (YC + LocalGlobe + 8VC + First Round + Khosla). 50k+ users early 2026; 33% … vendor
- Modalities text vendor
- Funding searched not found — prior $4M SigmaOS seed (2022) belongs to a different company (Sigma… third-party
- Pricing Free $0; Plus $10/mo ($8 annual); Pro $75/mo ($60 annual) vendor
- Data handling Fully on-device; no cloud processing; no telemetry; memory-based actions stay local; fun… vendor
- Deployment Managed-only (browser app install) vendor
- HQ San Francisco, CA, US third-party
- Founders / pedigree Nick Trenkler (co-founder); Alex Shapiro (CSO); Mahyad Ghassemi (founding CEO mentioned … third-party
- Memory volume / scale no scale claim vendor
- Backend storage custom (local) vendor
- Encryption at-rest + in-transit vendor
- Embedding model locked vendor
- Versioning immutable append-log vendor
- Tombstoning append-only no delete vendor
- Schema evolution free-form / no schema vendor
- Namespace primitives hierarchical vendor
- Contradiction handling always append (no resolution) vendor
- Forgetting policy user-controlled forget vendor
- Validated verticals consumer / individual (privacy-focused) vendor
- Time to running <10min (download Sigma) vendor
- Anti-fit not for cloud-LLM-required workloads (on-device only) vendor
- Optimised for fully-local LLM browser memory vendor
- Adjacent infrastructure self-contained Sigma + local model vendor
- Pros Privacy-positioned browser-as-agent with strong stance on no telemetry / no cross-site m… vendor
- Cons Newer entrant with small user base; sustainability depends on monetization clarity. vendor
- Project & sources sigmabrowser.com vendor
- architecture-deployment-locus computer-use vendor
- licensing-bucket commercial vendor
- positioning-platform-vs-product product vendor
- taxonomy-three-layer-rollup agent-infra repo
- compliance-certifications ccpa,gdpr vendor
What changed
Changes to this record's lifecycle, licence, release, pricing and hosting facts, from the catalog's git history. Subscribe (Atom)
- 2026-10-22
- Pricing first recorded as “Free $0; Plus $10/mo ($8 annual); Pro $75/mo ($60 annual)” source
- Funding / ownership “$4.1M total raised: $4M seed (Nov 2022 led by LocalGlobe + YC); additional ~$0.1M angels” → “searched not found — prior $4M SigmaOS seed (2022) belongs to a different company (SigmaOS, YC/San Francisco); Sigma Browser is Sigma Browser OÜ, Tallinn” source