What are the responsibilities and job description for the Senior Full-Stack Mobile Engineer position at Fizz?
Full-Stack Mobile Engineer
About Fizz
Fizz is the #1 money app for students and young adults. We are putting a financial ally into the pocket of every young adult.
We don't just rebrand financial products, we reinvent them. Fizz launched the first "debit card that builds credit" in 2023 with delightful features such as daily autopay and real-time AI spend limits. Since launch, we've helped over 100k users confidently build credit, start saving, and find line of sight to financial independence. We have real positive impact on our users.
We believe that Fizz is solving one of the most critical problems society faces today: A decline in optimism amongst young adults. Financial literacy amongst young adults has dropped to a 3-decade low. Only 8% express confidence in their ability to make financial decisions. Fizz is there for our customers during critical inflection points in their lives with actionable advice, and products that delight and remove any roadblocks on the path to success.
Fizz is backed by Kleiner Perkins, SV Angel, Y Combinator, and the founders of eight Unicorns, including Postmates, Public, and Checkout.com. In 2025, Fizz raised a yet-to-be-announced round from top-tier investors to double down on our growth.
We value in-person work in NYC. It helps us move faster, build genuine friendships, and collaborate to the nth degree.
Fizz was named 'Best credit builder' by Business Insider.
Role Overview
We need more firepower. As a Full-Stack Mobile Engineer, you will be instrumental in building and scaling our mobile user-facing application that serves over 100,000 users. You'll take end-to-end ownership of frontend development, raise the bar significantly for our engineering culture, and help shape the future of how young adults interact with financial products.
If you have grit and taste, are an opinionated truthteller, and take deep joy from crafting exceptional user experiences, Fizz is a place to deploy your skillset to drive fast-paced growth and make a real difference.
What You'll Do
Our product sits on top of many modern technologies, including a TypeScript/Node.js backend with Express, MongoDB for database storage, React for web applications, and Flutter for mobile platforms. We pride ourselves on leveraging AI wherever possible to speed up internal workflows.
Bonus Points
About Fizz
Fizz is the #1 money app for students and young adults. We are putting a financial ally into the pocket of every young adult.
We don't just rebrand financial products, we reinvent them. Fizz launched the first "debit card that builds credit" in 2023 with delightful features such as daily autopay and real-time AI spend limits. Since launch, we've helped over 100k users confidently build credit, start saving, and find line of sight to financial independence. We have real positive impact on our users.
We believe that Fizz is solving one of the most critical problems society faces today: A decline in optimism amongst young adults. Financial literacy amongst young adults has dropped to a 3-decade low. Only 8% express confidence in their ability to make financial decisions. Fizz is there for our customers during critical inflection points in their lives with actionable advice, and products that delight and remove any roadblocks on the path to success.
Fizz is backed by Kleiner Perkins, SV Angel, Y Combinator, and the founders of eight Unicorns, including Postmates, Public, and Checkout.com. In 2025, Fizz raised a yet-to-be-announced round from top-tier investors to double down on our growth.
We value in-person work in NYC. It helps us move faster, build genuine friendships, and collaborate to the nth degree.
Fizz was named 'Best credit builder' by Business Insider.
Role Overview
We need more firepower. As a Full-Stack Mobile Engineer, you will be instrumental in building and scaling our mobile user-facing application that serves over 100,000 users. You'll take end-to-end ownership of frontend development, raise the bar significantly for our engineering culture, and help shape the future of how young adults interact with financial products.
If you have grit and taste, are an opinionated truthteller, and take deep joy from crafting exceptional user experiences, Fizz is a place to deploy your skillset to drive fast-paced growth and make a real difference.
What You'll Do
- Take end-to-end ownership of the frontend development lifecycle—from architecture and implementation to testing, deployment, and optimization.
- Build out and iterate on our AI product initiatives
- Build and maintain high-quality applications using Flutter
- Collaborate closely with designers, product managers, and backend engineers to create intuitive, delightful user experiences
- Lead complex technical projects involving multiple engineers and push the design team to deliver world-class products
- Balance team collaboration with independent execution to meet ambitious goals and tight timelines
- Architect, refactor, and debug applications at scale without introducing regressions
- Work with observability tools like Datadog to monitor and optimize application performance
- Implement and maintain event tracking systems using tools like RudderStack and Segment
- Mentor junior developers and help establish engineering best practices
- 3 years of experience in mobile development with strong Flutter expertise
- Built and maintained mobile/web applications at scale—experience architecting, refactoring, and debugging applications with 100,000 users
- Strong experience with modern frontend tooling, testing frameworks, and CI/CD pipelines
- Experience with observability and analytics tools (Datadog, RudderStack, Segment)
- Startup experience and ability to thrive in fast-paced, ambiguous environments (wear lots of hats!)
Our product sits on top of many modern technologies, including a TypeScript/Node.js backend with Express, MongoDB for database storage, React for web applications, and Flutter for mobile platforms. We pride ourselves on leveraging AI wherever possible to speed up internal workflows.
Bonus Points
- TypeScript experience for web dev
- Full-stack capabilities
- Early employee at a hyper-growth startup
- Experience at world-class product orgs (ex: Brex, Ramp, Stripe, CashApp, Airbnb)
- Experience optimizing fintech onboarding flows and KYC processes
- Strong design sense
- Y Combinator experience
- Experience with financial services or regulated industries
- High potential for growth & complete ownership from the beginning 📈
- Work with colleagues who get it 🧠
- Rapid learning environment 🚀
- Generous equity in an early-stage startup 🤩
- 100% employer-paid medical benefits 🩺
- New York City Office with flexible WFH policy 💼
- Unlimited vacation policy with 15 official company holidays 🏝
- 401K plan with 4% company match 💪🏻
- 16 weeks of paid parental leave, including adoption and fostering
- Visa sponsorship is available for qualified candidates
Salary : $140,000 - $180,000
Senior Full Stack Engineer
flourish -
New York, NY