Senior Software Engineer - Fullstack API

👋 About Us

At sunday, we’re transforming the dining experience with fast, seamless payments. No more waiting for the bill — with one scan, guests pay, tip, and leave. We're creating a world where time is better spent enjoying the moment.

We’re a growing team of bold thinkers, builders, and creators, working across Europe and North America to bring better hospitality to life.

💼 About the Role

We’re looking for a Senior Fullstack Engineer to drive quality, scalability, and velocity in how we deliver guest-facing experiences.

This role sits at the intersection of backend and frontend engineering. You’ll lead by example, own complex features end-to-end, and help define how we build fast, maintainable, and user-friendly systems at scale.

We’re looking for someone who’s hands-on, product-minded, and excited to shape engineering practices across teams.

🔥 Key Responsibilities

• Build and own cross-functional features that touch React + TypeScript frontends and Kotlin-based APIs
• Drive technical decisions and contribute to architecture discussions, especially around modularity, observability, and performance
• Collaborate closely with design, product, and other engineers to ship high-impact features quickly and iteratively
• Bring clarity in ambiguous contexts: define API contracts, propose scalable patterns, and structure technical delivery
• Contribute to improving our design system, frontend tooling, and shared services
• Help guide code quality via reviews, mentoring, and shared engineering standards
• Document technical decisions (via ADRs) and communicate them clearly across the org

😊 About You

• minimum 5+ years of experience building production-grade web apps, with a strong focus on quality and ownership
• Deep proficiency in React and TypeScript, with an eye for scalable and clean front-end architecture
• Comfortable working with Kotlin or a similar backend language to build and evolve APIs (we have java legacy)
• Familiar with relational (PostgreSQL) and document databases (Firestore or similar)
• Experience building modular frontends, reusable components, and evolving design systems
• Autonomous, pragmatic, and capable of balancing speed with tech debt management
• Excellent communicator (written and verbal), especially in async, distributed environments

🖥️ Technical Edge

You don’t need to be an expert in everything, but the more of these boxes you tick, the better:

• Experience with backend for frontend and modular architecture
• Knowledge of OAuth flows, session management, and API security best practices
• Understanding of frontend security (XSS, CSRF, sandboxing)
• Familiar with logging, tracing, and performance monitoring tools (Datadog)
• Experience working on guest-facing apps in hospitality, payments, or consumer tech

🎯 Why This Role Matters

sunday is growing fast — and with that comes complexity. We’re scaling across products, markets, and teams. This role is about helping us bring clarity to that complexity.

You’ll play a key part in shaping the way we build and scale the front-end at sunday, making sure our guest-facing experiences are fast, delightful, and resilient — no matter how big we get.

⛳️ Compensation, Perks & Benefits

• Competitive salary (70 to 85k euros depending on seniority) and equity
• Remote-first friendly culture with flexible working hours
• The chance to build products used by millions across the globe
• 100% health coverage for you and your children
• Free vacation policy
• Opportunity for significant impact in shaping data strategies and innovative product development within a high-growth environment

sunday is an equal opportunity employer and does not discriminate and all qualified applicants will receive consideration for employment without regard to race, creed, color, sex, affectional or sexual orientation, gender identity or expression, gender, ethnicity, religion, national origin, ancestry, nationality, age, disability, marital status, veteran status, genetic information, or on any other basis prohibited by law (except where an attribute is a bona fide occupational qualification).