Job Closed
This listing is no longer active.
Flex splits your bills into smaller, stress-free payments throughout the month. Start today with your rent bill!
Senior Software Engineer, Fullstack
Location
California + 1 moreAll locations: California | New York
Posted
168 days ago
Salary
$197K - $213K / year
Seniority
Senior
Job Description
Senior Software Engineer, Fullstack
Flex
• Focus on creating exceptional user and partner experiences that drive engagement and retention. • Partner closely with product managers, designers, and data scientists, data analysts to identify and solve critical user onboarding challenges. • Design, develop, test, and deploy robust APIs, services and data pipelines that enhance user onboarding and overall platform experience. • Implement changes through an agile methodology, prioritizing rapid iteration and continuous improvement. • Utilize data and analytics to measure the impact of your work and identify opportunities for optimization.
Job Requirements
- 5+ years of professional software development experience.
- 3+ years of hands-on experience with Java.
- 3+ years of experience with React or React Native.
- 3+ years of experience with TypeScript.
- Having experience building high-quality mobile and web UIs to specifications is a must to have.
- Proficient in Java frameworks and tools used at Flex, including Spring (core/web/boot), Gradle, JUnit, and JVM (memory/performance tuning, GC).
- Experience with Service-Oriented Architecture, REST APIs, Message Queues, and scalable architectures.
- Experience with architectures and tools in React Native and React ecosystems (Hooks, Components, Context, Redux).
- Experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB) and containerization tools.
Benefits
- Competitive medical, dental, and vision available from Day 1
- Company equity
- 401(k) plan with company match (our company match kicks off at the beginning of 2026)
- Unlimited paid time off + 13 company paid holidays
- Parental leave
- Flex Cares Program
- Free Flex subscription
Related Guides
Related Job Pages
More Full-stack Engineer Jobs
- Build full-stack features using Next.js, React, TypeScript, Prisma, PostgreSQL - Use Cursor IDE and AI assistants to accelerate development - Design database schemas and optimize queries - Integrate third-party APIs (Stripe, Supabase, music services) - Develop admin dashboards and complex UIs - Own projects from requirements to deployment
Staff Software Engineer – Compliance
SardineCombine risk, compliance, and payment protection to increase customer trust and loyalty - all from one powerful API.
• Architect, design, and implement robust, efficient, and reliable backend services for KYC workflows, sanctions screening engines, and alert management systems • Build and optimize case management and alert creation pipelines that enable investigators to efficiently review and disposition suspicious activity • Develop and maintain integrations with regulatory reporting systems, including SAR filing and GoAML submissions • Collaborate closely with compliance stakeholders, product teams, and other engineering teams to translate regulatory requirements into scalable technical solutions • Contribute to developing new features and capabilities that enhance detection accuracy, reduce false positives, and streamline investigator workflows • Craft and maintain technical documentation for compliance systems, ensuring auditability and facilitating regulatory examinations • Play a pivotal role in shaping our company's engineering culture, ensuring the maintenance of high engineering standards across the organization
Software Engineer, Cloud API
CyberhavenWe protect important data other tools can’t see, from threats they can’t detect, across technologies they can’t control.
• You'll design and implement highly scalable and fault-tolerant solutions to discover and detect sensitive data across public clouds (e.g., AWS, GCP, Azure) and SaaS applications. • You'll be solving real-world scaling problems that require thorough performance analysis and troubleshooting skills • You get to work with a modern and constantly evolving microservices-based software stack which includes Go, Kubernetes, BigTable, BigQuery, Spanner, Redis, Docker, and more. • You'll write robust and secure-by-design hardened software that must withstand real-world attacks, while processing untrusted data and communicating with hundreds of thousands of endpoints over the internet.
This description is a summary of our understanding of the job description. Click on 'Apply' button to find out more. Role Description We are seeking a highly skilled and experienced Senior Fullstack Engineer to join our team. In this role, you will design, develop, and optimize both frontend and backend components that power our user-facing applications, including decentralized applications (dApps), a Web2/Web3-compatible Registrar, and domain marketplaces. You will play a critical part in building scalable, secure, and user-friendly systems that bridge traditional DNS with blockchain-based naming technologies. Familiarity with token standards (ERC-721, ERC-1155, ERC-20), wallet integrations, event-driven architectures, and distributed systems is essential. Responsibilities - Frontend - Collaborate with the product team to translate requirements into technical specifications and user-facing features. - Develop and maintain frontend components of the domain registrar and marketplace using Next.js, Typescript, React, GraphQL, HTML, and CSS. - Design and implement dApps that seamlessly integrate Web2 and Web3 APIs. - Build pixel-perfect UI from wireframes and high-fidelity mocks with attention to detail. - Contribute to open-source SDKs enabling developers to integrate Doma Protocol into their apps. - Write and maintain unit, integration, and E2E tests. - Ensure accessibility (WCAG), SEO, web performance best practices, scalability, and security. - Backend - Design, implement, and maintain backend services to support registrar features, domain tokenization, and Web2/Web3 marketplaces. - Build robust systems for payment processing, integrating fiat and crypto gateways. - Develop backend systems supporting event-driven architectures and asynchronous processing with Kafka, RabbitMQ, or similar tools. - Write scalable APIs, ensuring code quality through reviews, testing, and debugging. - Maintain and optimize existing services for performance and reliability. - Stay up to date with best practices and emerging technologies in web and blockchain development. Qualifications - Bachelor’s degree in Computer Science, Software Engineering, or related field (advanced coursework and certifications are a plus). - 5+ years frontend development (React, Vue, or Angular). - 5+ years backend development (Node.js with MySQL/Postgres). - Experience building highly scalable, distributed production systems. - CSS frameworks (Tailwind, Bootstrap) and responsive design. - Mobile-first design principles and optimization for small screens. - Web3 libraries (web3.js, ethers.js, wagmi). - Event-driven architecture and asynchronous processing. - Experience with APIs, microservices, and distributed systems. - Basic understanding of blockchain architecture and smart contract interaction. - Strong problem-solving, adaptability, and self-motivation. - Familiarity with Git, Agile methodologies, and CI/CD practices. - Excellent communication and teamwork skills. Pluses - Smart contract development (Solidity). - Experience with React Native or mobile development. - Familiarity with EPP (Extensible Provisioning Protocol) in domain systems. - Experience with NestJS, GraphQL. - DevOps experience (Kubernetes, AWS, GCP, DigitalOcean, Linux). - Accessibility design knowledge. Benefits - Ground-Floor Growth, Learning, and Impact: D3 is your chance to dive headfirst into an ultra-early-stage company where every move you make truly matters. You’ll have the opportunity to sharpen your skills, expand your expertise, and shape the foundation of something groundbreaking. - Strong, Proven Leadership: At D3, you’ll work alongside industry visionaries who have been there, done that, and are ready to do it again—only bigger. You’ll gain invaluable mentorship, develop a high-impact mindset, and be challenged to grow in ways you never imagined. - Unique Market Positioning: We’re pioneering at the intersection of internet infrastructure, real-world assets, and blockchain communities, creating solutions that redefine what’s possible in Web3.



