The archive · Developer & Business Tools · Product decision · 2025–2026
Bitrig bets people build native iPhone apps by chatting on the phone itself
Ex-Apple SwiftUI creators ship a custom Swift interpreter so anyone can vibe-code, test, and deploy native iPhone apps entirely from an iPhone; YC S25.
Bitrig
What the business is
Bitrig is an iPhone app that lets users describe an app in plain language, get native SwiftUI code generated by AI, preview it through a custom Swift interpreter, then compile and ship it to TestFlight or the App Store — no Xcode or Mac required.
How it started
Kyle Macomber and Jacob Xiao created SwiftUI at Apple and led it for about a decade; Tim Donnelly co-founded Storehouse (Apple Design Award winner, acquired by Square) and rewrote the fluid animation system behind iOS. In 2025 they founded Bitrig, joined YC's S25 batch, and launched the app on the App Store in August 2025.
What happened
The Launch HN on 2025-08-27 drew 188 points and 122 comments, with commenters impressed by the on-device interpreter but wary of crashes and data handling; GIGAZINE's hands-on review showed free users getting five AI exchanges a day and paid users unlimited chat plus TestFlight distribution. YC lists the company as active with a three-person San Francisco team.
How it ended up
Still live as of September 2026: YC lists Bitrig as an active S25 company and the product remains available on the App Store; no funding round or revenue figures have been published.
Background
Bitrig is an iPhone app for vibe coding: users describe an app in plain language, AI generates native SwiftUI code, and a custom Swift interpreter lets them run and preview it on the phone — then, with a paid Apple developer account, compile and submit it to TestFlight or the App Store. The pitch is 'Lovable for iPhone apps', with no Xcode or Mac involved.
The bet was that the blocker to mobile app creation was not model quality but tooling: Xcode only runs on macOS, so nobody had ever been able to run Swift on an iPhone. Kyle Macomber and Jacob Xiao — the creators of SwiftUI at Apple — plus designer Tim Donnelly (Storehouse, Apple Design Award) built a Swift interpreter that calls real iOS frameworks, letting an AI-generated app actually execute on the device.
Traction arrived fast: the Launch HN on 2025-08-27 drew 188 points and 122 comments, GIGAZINE published a hands-on review the next day confirming the App Store release with free and paid tiers, and HNDistilled's reception analysis documented users subscribing and building small apps within hours while flagging crashes and pricing. As of September 2026 YC lists Bitrig as active with a three-person team; no funding or revenue figures have been published.
What has to be true
- The founders had uniquely deep credibility: they created SwiftUI and led it for a decade, so the 'Apple-grade' claim was earned, not marketing.
- A real on-device Swift interpreter was a defensible technical moat that wrappers around the same LLMs could not copy overnight.
- The distribution insight — build apps on the device where apps live — matched a genuinely new habit of creating from a phone.
- Launching on HN gave instant, honest feedback that shaped the product (stability, privacy, pricing) before scaling.
What can be applied
When the obvious product seems impossible — you can't compile Swift on an iPhone — the edge is building the missing artifact: a real interpreter made the category possible, not a better prompt.
Aftermath
As of 2026-09-02 Bitrig is active: YC lists the S25 startup with a three-person team in San Francisco, and the app remains available on the App Store with free and paid tiers. The company has not published funding, revenue, or download figures, and no pivot or shutdown has been announced.
Sources
- Launch HN: Bitrig (YC S25) – Build Swift apps on your iPhone
- bitrig: Vibe code, test, and deploy Swift apps. All from your iPhone.
- iPhoneでAIとチャットするだけで超絶簡単にアプリを作成できる「Bitrig」を使ってみた
- Launch HN: Bitrig (YC S25) – Build Swift apps on your iPhone
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