Senior Software Engineer
Date:
About RIINA
RIINA is building team sports for people who train alone: a social fitness app that turns workout data into competition, team identity, and shared momentum. We're creating a new category — social fitness built around team accountability rather than solo tracking. The app launched on the app stores in August 2026. You'd join three experienced co-founders and a stellar Marketing Lead, with meaningful ownership and direct influence on how the platform looks and works from the start. The role is remote, with the option to work from our offices in Porto for in-person collaboration, meetings, and team building.
The role
We're looking for a senior engineer who ships. You'll take features from idea to release and beyond, across the mobile app, backend services, wearable integrations, and the data pipelines behind our scoring and AI models. You work in Rust, TypeScript, and Python, and you're comfortable moving between them. You have good product judgment — you care how something feels to use, not just how it's built — and you work autonomously: you figure things out, make decisions, and keep moving rather than waiting for direction. You use AI tools aggressively to move faster, and you're always looking for the next way to do so.
What you’ll do
- Build and ship features that help people join teams, compete, connect, and keep coming back
- Own work end to end — from initial idea through release, monitoring, and ongoing improvement — in line with the product roadmap
- Improve wearable integrations, activity syncing, and scoring reliability so users can trust their results
- Build data pipelines for auto-labeling and automated training loops for our proprietary AI models
- Keep the experience fast and responsive, and react quickly when issues come up
- Turn user feedback into clear, practical improvements together with product, design, and marketing
- Make thoughtful technical decisions, review code, and maintain the testing and monitoring needed to ship confidently
- Contribute to mobile architecture, design discussions, and technical trade-off evaluations
- Spot technical risks, dependencies, and integration challenges early and drive them to resolution
- Provide production support: root cause analysis, fixes, and preventative improvements
- Communicate status, risks, and decisions clearly to leadership
What we’re looking for
- 4+ years shipping and maintaining production software used by real people
- Strong mobile development, backend engineering, or both — and willingness to work across the whole product
- Comfortable working in Rust, TypeScript, and Python
- High autonomy and a bias to action: you take initiative, make calls, and get things done without needing every detail handed to you
- You use AI tools in every part of your workflow to move faster
- Solid understanding of APIs, data models, authentication, and reliable data processing
- Experience building data pipelines — ideally for auto-labeling and automated model training loops
- Ownership from implementation through what happens after launch
- Comfort in a small team where priorities evolve as we learn
- A genuine fitness and wearable enthusiast — this one is a requirement, not a preference
Nice to have
- Consumer apps, wearable or health data, social features, notifications, or subscriptions
- Training or deploying proprietary ML models in production
- Speaking Portuguese
In case this sounds interesting to you, kindly send your application to jobs@riina.io
Apply for this role
