SigmaOS
SigmaOS is a macOS-only workspace browser that reimagines tabs as tasks — organized into workspaces, markable complete, lockable — with vertical tabs and split-screen. Tier T3 (first-party site). It’s built on WebKit (Safari-like performance/battery) but supports Chrome extensions, and ships an AI assistant, Airis, for contextual help and summarization. Free Personal tier (limited AI); Pro $20/mo, Max $30/mo unlock unlimited AI.
SigmaOS anchors the productivity current — the browser as a work-organization surface (tabs = to-dos) rather than an AI agent — but note it also bundles AI (Airis), so even the productivity pole now reaches for an assistant. Its niche is the power-user / founder workflow, the same audience browser-wars-2026 groups with Zen and the tab-management lineage.