Cross-Platform App Developer for BLE-Connected Smart Toothbrush (TWYST)
Budget: $3,000 – $5,000 USD
Project Overview
TWYST is a design-forward oral care brand reinventing the brushing experience through smart
hardware and replaceable gel capsules.
Our flagship product is a BLE-enabled electric toothbrush that dispenses toothpaste from
proprietary capsules. The brush syncs with a mobile companion app that provides brushing
feedback, capsule usage tracking, and device control.
We’ve completed the hardware and BLE protocol and are now seeking an experienced cross-
platform mobile app developer to bring the TWYST companion app to life on iOS and Android.
What’s Ready on Our End
We will provide:
- Finalized BLE protocol spec and command logic
- Structured UI Logical Flow documentation
- Complete TWYST icon pack, 3D product renders, and style guide
- Internal command + response flow maps (TWYST App Commands; Data Flow)
- BLE protocol reference in live Google Sheets (“lively docs”)
- Full brand assets: logo, color, and animation files
Your Core Deliverables
You will be responsible for building a fully functional, production-ready TWYST mobile app:
1. Bluetooth (BLE) Integration
- Connect to TWYST toothbrush via BLE
- Implement custom command structure (GATT)
- Handle characteristic notifications, write commands, and async BLE responses
- Include reconnection handling and session persistence logic
- Optimize BLE latency and implement debounce logic
2. Device Control & Logic
- Map UI buttons to BLE actions (e.g., brushing mode, dispense trigger)
- Read capsule UID and store brushing history
- Log brushing session details: duration, pressure (from sensor), mode, capsule status
- Handle firmware-driven events (low battery, capsule empty, etc.)
- Build an internal state machine to represent brush status
3. UI/UX Implementation
- Build pixel-perfect UI using:
o UI Logical Flow Sequence.pptx
o TWYST Brand Identity & Style Guide.pdf
o Custom icon pack and logo set
o TWYST 3D renders (to match visuals across app, site, and packaging)
- Display (as mentioned previously, we already have these assets):
o Brushing cycles
o Capsule dispense confirmation
o Battery alerts / low-fill warnings
- UI should visually draw inspiration from Oral-B’s mobile application (it should look and
feel similar).
4. Local Data Storage
- Store brushing session logs and capsule tracking data locally (SQLite or device storage)
- Allow for minor personalization:
o Light color
o Language
o Brushing Mode
o Units (mL/oz)
5. Testing & QA
- Validate functionality across:
o Latest iOS/Android OS versions
o At least 2 real devices per platform
o Simulated BLE dropouts, reconnects, command conflicts
o Device variations (iPhone 12–16, Galaxy S21–S25, Pixel 6–9)
- Ensure seamless performance and error recovery across BLE edge cases
6. Hardware Collaboration
- Coordinate with TWYST’s electronics partner (PN) in Mainland China
- Collaborate using live Google Sheets to debug BLE events and align logic
- Must be comfortable working asynchronously and joining occasional live meetings to
align firmware + app development
7. App Store Submission
- Deliver App Store and Google Play ready builds
- Implement:
o App metadata
o App icon, splash screen (we’ll provide)
o Store-ready screenshots (with guidance from brand visuals)
8. Handoff & Maintenance
- Provide:
o Full source code
o Git repository setup
o BLE logic + UI mapping documentation
o Build instructions for updates and submission
- Offer post-launch support or retainer model for fixes or new features, if interested
Technical Expectations
- Cross-platform app development using Flutter, React Native, or similar
- Native experience (Swift / Kotlin) welcome if aligned with timeline
Must have:
- Deep BLE experience with custom GATT profiles (not just fitness band work)
- Async BLE characteristic listener handling
- State machine development experience
- Local DB implementation (SQLite, CoreData, etc.)
Timeline & Budget
-Estimated timeline: 6–8 weeks
-Target budget: $5,000 USD
(Some flexibility based on experience, speed, and post-launch support)
-Payment milestones will be aligned with build stages and functionality reviews
Ideal Candidate
-Has built BLE-connected apps (bonus for smart toothbrushes, shavers, or IoT consumer
devices)
-Proven experience with mobile app and hardware integration
-Passion for user-centric design and clean UX implementation
-Reliable, collaborative, and timezone-aware (especially with China)
How to Apply
Please include:
-Portfolio or app links (ideally BLE-connected products or healthtech)
-Brief intro: your preferred tech stack, approach to BLE integration, and project timeline
Any questions you have for us, we’re happy to provide protocol snapshots before
interview
We’re excited to meet someone who’s ready to help make TWYST one of the most beautifully
integrated hardware+app experiences in the DTC space.
We’ll begin interviews this week. Thank you!
TWYST is a design-forward oral care brand reinventing the brushing experience through smart
hardware and replaceable gel capsules.
Our flagship product is a BLE-enabled electric toothbrush that dispenses toothpaste from
proprietary capsules. The brush syncs with a mobile companion app that provides brushing
feedback, capsule usage tracking, and device control.
We’ve completed the hardware and BLE protocol and are now seeking an experienced cross-
platform mobile app developer to bring the TWYST companion app to life on iOS and Android.
What’s Ready on Our End
We will provide:
- Finalized BLE protocol spec and command logic
- Structured UI Logical Flow documentation
- Complete TWYST icon pack, 3D product renders, and style guide
- Internal command + response flow maps (TWYST App Commands; Data Flow)
- BLE protocol reference in live Google Sheets (“lively docs”)
- Full brand assets: logo, color, and animation files
Your Core Deliverables
You will be responsible for building a fully functional, production-ready TWYST mobile app:
1. Bluetooth (BLE) Integration
- Connect to TWYST toothbrush via BLE
- Implement custom command structure (GATT)
- Handle characteristic notifications, write commands, and async BLE responses
- Include reconnection handling and session persistence logic
- Optimize BLE latency and implement debounce logic
2. Device Control & Logic
- Map UI buttons to BLE actions (e.g., brushing mode, dispense trigger)
- Read capsule UID and store brushing history
- Log brushing session details: duration, pressure (from sensor), mode, capsule status
- Handle firmware-driven events (low battery, capsule empty, etc.)
- Build an internal state machine to represent brush status
3. UI/UX Implementation
- Build pixel-perfect UI using:
o UI Logical Flow Sequence.pptx
o TWYST Brand Identity & Style Guide.pdf
o Custom icon pack and logo set
o TWYST 3D renders (to match visuals across app, site, and packaging)
- Display (as mentioned previously, we already have these assets):
o Brushing cycles
o Capsule dispense confirmation
o Battery alerts / low-fill warnings
- UI should visually draw inspiration from Oral-B’s mobile application (it should look and
feel similar).
4. Local Data Storage
- Store brushing session logs and capsule tracking data locally (SQLite or device storage)
- Allow for minor personalization:
o Light color
o Language
o Brushing Mode
o Units (mL/oz)
5. Testing & QA
- Validate functionality across:
o Latest iOS/Android OS versions
o At least 2 real devices per platform
o Simulated BLE dropouts, reconnects, command conflicts
o Device variations (iPhone 12–16, Galaxy S21–S25, Pixel 6–9)
- Ensure seamless performance and error recovery across BLE edge cases
6. Hardware Collaboration
- Coordinate with TWYST’s electronics partner (PN) in Mainland China
- Collaborate using live Google Sheets to debug BLE events and align logic
- Must be comfortable working asynchronously and joining occasional live meetings to
align firmware + app development
7. App Store Submission
- Deliver App Store and Google Play ready builds
- Implement:
o App metadata
o App icon, splash screen (we’ll provide)
o Store-ready screenshots (with guidance from brand visuals)
8. Handoff & Maintenance
- Provide:
o Full source code
o Git repository setup
o BLE logic + UI mapping documentation
o Build instructions for updates and submission
- Offer post-launch support or retainer model for fixes or new features, if interested
Technical Expectations
- Cross-platform app development using Flutter, React Native, or similar
- Native experience (Swift / Kotlin) welcome if aligned with timeline
Must have:
- Deep BLE experience with custom GATT profiles (not just fitness band work)
- Async BLE characteristic listener handling
- State machine development experience
- Local DB implementation (SQLite, CoreData, etc.)
Timeline & Budget
-Estimated timeline: 6–8 weeks
-Target budget: $5,000 USD
(Some flexibility based on experience, speed, and post-launch support)
-Payment milestones will be aligned with build stages and functionality reviews
Ideal Candidate
-Has built BLE-connected apps (bonus for smart toothbrushes, shavers, or IoT consumer
devices)
-Proven experience with mobile app and hardware integration
-Passion for user-centric design and clean UX implementation
-Reliable, collaborative, and timezone-aware (especially with China)
How to Apply
Please include:
-Portfolio or app links (ideally BLE-connected products or healthtech)
-Brief intro: your preferred tech stack, approach to BLE integration, and project timeline
Any questions you have for us, we’re happy to provide protocol snapshots before
interview
We’re excited to meet someone who’s ready to help make TWYST one of the most beautifully
integrated hardware+app experiences in the DTC space.
We’ll begin interviews this week. Thank you!