Natural Cycles° is a leading women’s health company that developed the world’s first birth control app, used by millions globally. We are a fast growing startup, and we promote an international working environment filled with smart and ambitious colleagues based in Stockholm, Geneva, New York, and remotely. Our mission is to pioneer women’s health through research and passion, empowering every woman with the knowledge she needs to take charge of her health.

We’re looking for an engineer who loves building things end-to-end, someone who lives in firmware but isn’t afraid to pick up a soldering iron, spin a test jig, or open Xcode to verify an app integration.

You’ll work directly with the Head of Hardware to prototype, test, and refine the next generation of wearable devices, bridging firmware, hardware, and app layers. You’ll be encouraged to generate code and move fast to explore ideas or solve problems.

If you’re motivated by curiosity and iteration, and want to work across the stack from firmware optimization to app development and data analysis, this is an opportunity to do exactly that.

Please note that we are hiring for this role in Stockholm, Sweden.

What you will be doing

You’ll be hands-on across several active hardware programs, supporting:

Firmware Development & Optimization

• Implement and improve sensor drivers, data collection, and low-power algorithms
• Maintain and improve BLE communication, background updates (FOTA), and data transfer
• Customize and structure raw logs for testing and analytics
• Debug firmware plugins and integrate analytics for data validation
• Profile and reduce battery consumption across operating modes

Hardware Prototyping & Validation

• Perform hardware modifications and assist in sensor integration or board validation
• Contribute to test setups for endurance, temperature, and performance validation
• Support design iterations (materials, ergonomics, assembly feedback)
• Participate in certification and compliance efforts

App & Tooling Collaboration

• Use code generation tools to develop, extend or debug iOS and Android apps
• Prototype app-side visualizations
• Collaborate with software engineers to verify firmware to app data flows
• Contribute to automation and data validation pipelines when needed

What skills and experience we think you have

• 3 to 5 years of experience and a strong background in embedded systems, firmware, or electrical engineering
• Proficiency in C/C++ and familiarity with ARM-based MCUs (e.g., nRF52, STM32, CC2642)
• Experience with BLE, sensor interfacing (I²C/SPI), and low-power design
• Comfort with hardware tools (oscilloscope, soldering, basic rework, or prototype bring-up)
• Interest in using AI-assisted development tools (Cursor, Copilot, etc.) for both firmware and app experiments
• A practical, experimental mindset you test ideas early, measure results, and iterate fast

Bonus Points

• Familiarity with data analysis and app analytics
• Experience with Swift (iOS), Kotlin (Android), or cross-platform frameworks like Ionic or React Native
• Exposure to temperature or optical sensing systems
• Understanding of wearable power management and BLE stack tuning
• Curiosity about digital health, female physiology, or biometric sensing

Why You’ll Love It Here

• Work directly with Natural Cycles’ Head of Hardware on wearable development
• Freedom to experiment from firmware to hardware to app-level
• Use modern tools and do real-world R&D with a clear objectives and goals
• Be part of a small, deeply technical team where ideas move fast and impact is tangible

Location

We are remote-friendly, but we find great value in connecting in person. For this role, you’ll collaborate closely with our Head of Hardware, who is based in Stockholm.

Not living in Sweden? No problem! We offer relocation support to help you move.

Sounds interesting?

If you want to be part of a successful team, we encourage you to apply for this position as soon as possible. We look forward to hearing from you!

How to apply

To apply, just upload your CV and answer the questions on the application form. Keep in mind that we can't accept applications through email because of GDPR, and only applications submitted via the career site (and in English) will be considered.

At Natural Cycles we value diversity and inclusion because we know that teams with people from different backgrounds and experiences are stronger. We welcome candidates from all walks of life and are committed to creating an inclusive environment for all employees and candidates.

Note: We are not looking for consultants or help from recruitment agencies