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Built by Zev and Tia in tandem

faBolus — your pump, on your wrist and your phone.

faBolus is a remote for insulin pumps: see your glucose and pump status at a glance, and deliver a bolus from your iPhone, a Garmin Venu 3S, or a Home/Lock Screen widget. It supports the Tandem t:slim X2 — the Mobi isn't supported in this version.

Build it yourself Read the safety notes

Experimental — in development

faBolus is an independent, open-source project in development for experimental use. It is not FDA-cleared; if you build and use it, you assume all responsibility. See Safety.

Start here

  • Safety

    What faBolus is, the interlocks built in, and how to use it responsibly.

    Safety notes

  • What you'll need

    The hardware, accounts, and tools — a pump, an iPhone, a Mac, and a free or paid Apple ID.

    Requirements

  • Build it yourself

    A step-by-step, no-experience-required guide: Apple account → Xcode → your iPhone and Garmin.

    Build guide

  • Customize

    The in-app Settings tab — bolus defaults, chart options, glucose alert thresholds, and more.

    Settings

What it does

  • A tabbed, modern app

    Dashboard · Bolus · Alerts · Settings. The Dashboard shows glucose with a trend and a 3 / 6 / 12 / 24-hour chart — with an optional IOB overlay and bolus bars — over a details card with everything from the pump (carb ratio, correction factor, target, max bolus, reservoir, battery, CGM, last bolus). Every reading shows its age, and anything older than 6 minutes is shown greyed — never as the current value.

  • Boluses, with guardrails

    Enter units, or enter carbs + BG and let the pump's calculator recommend a dose. Every bolus has a max-units clamp and an explicit confirmation, can be cancelled mid-delivery, and reports the actual amount delivered.

  • Garmin Venu 3S remote

    Request a bolus from your wrist. The remote never touches the pump directly — the iPhone owns the connection and confirms every request. The watch gets a glucose complication and a history screen.

    Garmin remote

  • Widgets

    Lock/Home Screen widgets for glucose and an overview, plus a Quick Bolus widget with a 1-2-3 confirm you can trigger without opening the app.

    iPhone widgets

  • Glucose via Dexcom Share

    Glucose normally comes through the pump. Dexcom Share is the one optional backup source — a cloud-polled feed that keeps a reading flowing if the pump-to-sensor link drops. Stale readings are never shown as current. Learn more.

Under the hood

faBolus is built on an open protocol core, and the Garmin watch app lives in its own repository.

Repository What it is
TandemKit The Swift protocol / auth / Bluetooth core: message framing, HMAC signing, pairing, Core Bluetooth. Every outgoing message is tested byte-for-byte against the pumpX2 cliparser oracle.
faBolus The faBolus iPhone app, iPhone widgets, and the shared phone↔remote command contract. Consumes TandemKit.
faBolusGarmin The faBolus Garmin (Connect IQ) watch remote. Pairs to the iPhone app.

Built on pumpX2 — thank you, James Woglom

faBolus stands on the shoulders of pumpX2 by James Woglom (@jwoglom). His reverse-engineering of the Tandem pump's Bluetooth protocol is the foundation of this entire project — TandemKit is a Swift port of that work, validated byte-for-byte against pumpX2's cliparser oracle. faBolus would not exist without it. The project also draws on the wider LoopKit / Loop ecosystem for parts of its visual design and documentation. See NOTICE.md for full attributions.

Independent project

faBolus is an independent, open-source project. It is not affiliated with, endorsed by, or a product of Tandem Diabetes Care or Dexcom. Tandem, t:slim X2, Mobi, and Dexcom are trademarks of their respective owners.