September 10, 2026 · 6 min read
Frontier intelligence you can hand real work.
Most AI answers questions about work. Arche 1.0 does the work — 300 clicks across 4 apps replaced by one sentence. It runs world-class open weights inside a harness built for privacy and safety, and it scores shoulder-to-shoulder with the biggest closed models on the benchmarks that measure real doing.
Why this is a big deal
Best score on 4 agentic benchmarks — BrowseComp, SWE-Marathon, ProgramBench and τ³-Banking — against GPT-5.6 Sol, Claude Opus 5, Claude Fable 5 and Claude Opus 4.8.
A full project in one context window. Codebases, inboxes, research dossiers — Arche reads it all at once and acts on it, instead of forgetting page two.
The agent never holds your secrets. The sealed vault masks everything to sec_•••• — even from the model itself. Nothing sensitive acts without your yes.
Benchmarks: Arche 1.0 vs the frontier
Published technical results — Arche 1.0 (Kimi K3 at max reasoning effort) against current frontier models. Bold marks the best score per row. Arche takes the top spot on BrowseComp, SWE-Marathon, ProgramBench and τ³-Banking, and sits within a point or two of the leader almost everywhere else.
Source: Moonshot AI Kimi K3 technical results; competitor scores as reported in the same release (each evaluated in its own vendor harness). Arche 1.0 serves these weights through the Belna privacy-first harness.
The harness: why Arche is more than its weights
A brilliant model with no hands is just a chatbot. The Belna agentic harness is what turns intelligence into finished work — safely:
✅ Approvals by default
Sensitive actions — apps, browsing, external writes — pause for your explicit yes, or an always-allow rule you can revoke anytime under Vault → Approved.
🔒 Sealed vault
Secrets are encrypted at rest and masked everywhere: chat, traces, model context. The agent only ever sees references like sec_••••. Reveal is for your eyes alone, on your device.
🧪 Sandboxed doing
Code, browser and computer use run contained with an allowlisted network. External integrations are read-only via your own per-request token — never stored, never logged.
👁 Visible trace
Every step lands in the Trace tab. Belna never pretends to browse, run code or read email unless the trace shows it. Check the work, don't just trust it.
- Smart mode
- Deepest reasoning — research, builds, reviews
- Fast mode
- Snappy everyday answers at lower cost
Still open at the core
Arche 1.0 is built on Kimi K3 by Moonshot AI — fully open-source, open weights. Anyone can inspect the foundation we're standing on; there is no black-box base model. What Belna adds is everything around it: the agentic harness, the safety layer, the memory and vault, the Swedish-hosted product that keeps your data yours.
Openness is the point. Frontier capability shouldn't require handing your life to a closed box — and now, on the benchmarks that matter for real work, it doesn't have to.
Free starts with 20 credits. Pro $30/mo → 60 credits monthly + $50 gift card. Max $50/mo → 100 credits monthly + $100 gift card.