Alpaca Scalper

iOS app · Expo / React Native · 2026

Built with: Expo, React Native, TypeScript, Alpaca API, Secure Store, EAS

Alpaca Scalper is an iPhone app for scalping: quick trades that aim for small gains. It works with Alpaca paper and live accounts. It started life as a Google Apps Script web app, and I rebuilt it as a native app with big, easy-to-hit buttons.

Nothing here is investment advice.

Trade screen with buying power, a position, and an open sell order — Trade

Session chart with scalp readiness checks — Chart and readiness

What it does

One tap places a market buy, and the app follows up with limit sells priced to cover regulatory fees, so a small win isn't eaten up by costs. Before any order goes out, it checks the preset against your buying power, the current spread, and fees.

For context, there's a snapshot of the day's chart and a scalp check that looks at the spread, the day's range, fees, and volume. There's also an optional live feed that watches for flash crashes over a WebSocket. It's off by default.

Under the hood

Expo and React Native with TypeScript.
API keys are entered in the app and kept in the device's Secure Store, never in the code.
Installed with EAS Build, with over-the-air updates through EAS Update.