Underdog AI Assistant Launches in Beta With On-Device Privacy and a Transaction-Fee Business Model
Underdog’s invite-only beta runs a 27-billion-parameter Qwen3.8-27B model entirely on Macs and Windows PCs, keeping credentials and personal data on-device. The free, ad-free app plans to monetize via a small cut of Stripe transactions.
Silicon Valley developer Sigil Wen launched an invite-only beta of Underdog, an on-device AI assistant, on Monday, October 6, 2026. The app runs entirely on users’ own hardware — currently Macs and Windows PCs — with Linux, iPhone, and Android versions planned.
Wen, a Thiel Fellow, built Underdog through his startup Conway Research. Because the AI model never leaves the user’s device, personal data — including access credentials for connected email and other accounts, which Underdog encrypts — is not sent to external servers. To power the app, Wen developed a custom inference engine called Husky, which he says moves less data between a computer’s main chip and its graphics chip than comparable engines, resulting in faster performance.
Underdog currently runs a 27-billion parameter reasoning model fine-tuned from Qwen3.8-27B. Wen says the model is competitive with Claude Opus 4.6 on some benchmarks and is capable enough for everyday tasks such as shopping research and answering math questions.
The app will be free and will not carry ads. Because inference runs on users’ machines rather than Wen’s servers, he says his operating costs are low enough to forgo a subscription fee. Instead, Conway Research plans to earn revenue by taking a small percentage of payment transactions the assistant processes through Stripe’s payment rails — similar to an interchange fee. Stripe co-founder Patrick Collison is among Underdog’s angel investors.
That model could matter to users who are wary of AI assistants that, according to Wen, may collect sensitive personal, medical, or financial data to sell to advertisers or use for model training. “Why should using AI require surrendering your private information?” Wen wrote in a published manifesto.
Conway Research is backed by Andreessen Horowitz partner Chris Dixon, Khosla Ventures, Hummingbird, SV Angel, and the Anthology Fund — the partnership between Menlo Ventures and Anthropic — along with angel investors including Vercel founder Guillermo Rauch, OpenAI researcher Noam Brown, and Deedy Das.