[!CAUTION] Not a medical device. Do not use it for treatment decisions. faBolus is experimental software under active development. It is not FDA-cleared or approved and has not been clinically validated. Do not rely on it to make or carry out any insulin-dosing, treatment, or other clinical decision. It is for software development and evaluation only: always confirm every reading and dose directly on your pump and CGM, and talk to your healthcare provider about your therapy.

faBolus

A remote-bolus and status-viewing app for the iPhone, designed to be pump-agnostic. The iPhone owns the pump's Bluetooth connection; a Garmin Venu 3S watch and the Home/Lock Screen widgets (including Quick Bolus) are thin remotes that relay confirmed commands to the phone; they never talk to the pump directly.

Today it works with one pump: the Tandem t:slim X2, via TandemKit. (Tandem's Mobi isn't supported in this build: the app declines to pair with one.) The app talks to the pump only through a backend interface, so support for other pumps can be added without forking, see ARCHITECTURE.md.

Dexcom Share (optional): glucose normally arrives through the pump. faBolus can also poll Dexcom Share as a fallback so a reading keeps flowing if the pump's own glucose goes stale. The pump stays the primary source, and a Share reading is shown marked, never as current. See Glucose (Dexcom Share).

Built by Zev and Tia in tandem.

[!WARNING] Experimental, in development. faBolus is an independent, open-source project in development for experimental use. It is not FDA-cleared; if you build or use it, you assume all responsibility. Not affiliated with, endorsed by, or a product of Tandem Diabetes Care or Dexcom.

📖 Documentation

Full docs (a no-experience-required build guide, usage, and customization) live at the documentation site:

👉 https://fabolus.org/

• Safety, read before anything else.
• Build it yourself: Apple account → Xcode → iPhone, step by step, plus the Garmin app (and a command-line build).
• Using the app · Settings & options.

💬 Feedback

Bug, confusion, or an idea, technical or not? See Send feedback, or go straight to the feedback form (or email [email protected]). faBolus is experimental and not FDA-cleared. For anything urgent about your therapy, contact your healthcare provider.

Using it alongside the official Tandem app

The pump pairs to one controller at a time, so faBolus and the official t:connect app can both be installed but only one is connected at once, and switching is a full re-pair with a new 6-digit code, not a quick toggle (the pump doesn't store two pairings, and the code can't be shared between apps). faBolus isn't a full replacement either: some pump settings can only be changed in t:connect. Pick faBolus as your everyday controller (it reconnects with no code) and pair t:connect only when you need an official-app-only setting, then re-pair faBolus. More in the FAQ and Pairing.

Layout

Packages/faBolusCore/        # in-repo SwiftPM package: the stable contracts + neutral models
                             #   (PumpBackend, PumpCapabilities, PumpAlert, RemoteCommand, GlucoseSource + GlucoseArbiter)
Packages/ShareClient/        # Dexcom Share follower, vendored from LoopKit/dexcom-share-client-swift (MIT)
ios/faBolus/                 # iOS host app, owns the pump connection; tabbed UI
ios/faBolus/Data/            # backends (TandemBackend, MockBackend) + BackendRegistry + hosts
ios/faBolus/Data/Sources/    # the Dexcom Share glucose follower + its keychain credential store
ios/faBolusWidgets/          # Lock/Home Screen widgets (incl. Quick Bolus)
Shared/                      # WidgetShared (App Group snapshot) + widget bolus intents
schema/                      # THE phone↔remote message contract, single source of truth
hosts/                       # sketches for hosting the remotes from another app (e.g. Loop)
docs/                        # the documentation site (MkDocs Material)

This is narrow main: a small, hardware-validated core. A number of surfaces an earlier build of this app had (other remotes, other CGM sources, an advisory meal-detection assistant, and more) live on experimental and their own dev/<surface> branch instead; see BRANCHES.md §1.2c for the full roster and why.

New pumps and new host apps are added in-tree behind stable interfaces, not by forking: see ARCHITECTURE.md for the two seams and CONTRIBUTING.md for step-by-step "add a pump backend" / "host the remotes" guides.

• The iOS app + widgets are targets of one Xcode project (faBolus.xcodeproj), generated from project.yml with XcodeGen. Depends on TandemKit via SPM.
• The Garmin (Connect IQ / Monkey C) remote lives in its own repo, faBolusGarmin; the iPhone-side bridge stays here and talks to it over the shared schema/.
• The widgets read a snapshot the app publishes to a shared App Group; they can't drive Bluetooth, so they show the last published value with its age (older than 6 minutes shows marked).

Build (quick reference)

Full walkthrough: docs/build. In short:

git clone --recurse-submodules https://github.com/faBolus-app/TandemKit.git
git clone https://github.com/faBolus-app/faBolus.git
cd faBolus
./scripts/generate-project.sh      # generates faBolus.xcodeproj (auto-detects the Garmin SDK)
open faBolus.xcodeproj             # set your Team under Signing & Capabilities, then Run

Requires Xcode 16+ and an Apple ID (free works; paid recommended).

Garmin is optional at build time. scripts/generate-project.sh auto-detects the Connect IQ Mobile SDK for iOS: if it's not present, the app builds without Garmin (no SDK needed) and shows a note where Garmin pairing would be. To use a Garmin watch, place the Connect IQ SDK where project.yml expects it (see docs/build) and re-run the script (force Garmin on/off with FABOLUS_GARMIN=1/0). Plain xcodegen generate still works.

Status

The protocol/BLE/auth core (TandemKit) supports read-only monitoring, JPAKE pairing, and a signed bolus path validated on hardware. This app layer is under active development on top of it.

Acknowledgments

faBolus is built on 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. (faBolus is an independent reimplementation, not a fork of, affiliated with, or endorsed by pumpX2/controlX2.)

It also draws on the wider LoopKit / Loop ecosystem: the app's visual design and parts of this documentation take inspiration from Loop and LoopDocs.

Full attributions are in NOTICE.md.

License & trademark

Code is MIT-licensed (see LICENSE). faBolus™ is a trademark of Zev Granowitz; the license covers the source code, not the name, logo, or branding. Forks are welcome under the MIT terms; please don't use the faBolus name in a way that implies your fork is the official project. See NOTICE.md for details.