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Idle Macs, private prompts, open models.
Umbra is a marketplace for private-prompt inference on attested Apple Silicon: it puts idle Macs to work and gives developers a home for the models incumbents will not host.
Machine owners host public models on hardware they already own and earn per token; developers reach them through an API that speaks the formats they already use. The hard part is trust, so prompt privacy is a property of the system, not a policy: even an adversarial provider cannot read your prompt.
That is the name. In a total eclipse, the umbra is the innermost shadow: the region where the light source is completely hidden from view. Your prompts run inside it, and attestation is what makes the darkness provable instead of promised.
Monetize idle Apple Silicon
Turn idle Macs into an inference provider that hosts public open-weight models and earns per token, on hardware you already own.
The long-tail models incumbents will not host
Uncensored models and community fine-tunes, on an OpenAI- and Anthropic-compatible endpoint. Keep your SDK, change the base URL.
Private prompts, enforced by attestation
Prompts and outputs are never logged, written to disk, or stored, not even by the machine owner. Enforced by closing the software paths and proving the hardware with Apple attestation, not by a promise.
An experimental alpha, built in the open
Umbra is a small experimental alpha. Every hosted model is a public, open-weight model an independent provider pulls with their own Hugging Face key, run in-process behind a confidential coordinator that never sees prompt text. We ship honestly and say what is not ready rather than overstate it.