Senior Full Stack Engineer

THE ROLE Tolken is a deeply technical team looking for a builder who craves complexity and ownership. You will work across the stack, from the core ledger to the user interface, ensuring systems are not just functional, but hyper-scalable, secure, and auditable. You will be hands-on in design, implementation, and deployment, collaborating closely with the founders to ship production-grade features in a high-velocity environment. KEY RESPONSIBILITIES - Design, build, and maintain end-to-end features across backend (ledger, routing services) and frontend (React-based UI). - Implement and evolve production-grade APIs, data models, and integrations for a high-throughput financial system. - Own the full lifecycle of features: design, implementation, testing, deployment, and ongoing reliability in production. - Collaborate closely with the VP of Engineering, founders, and other engineers to translate product requirements into technical designs and delivery plans. - Improve performance, scalability, and observability of the platform through profiling, tuning, and better monitoring. - Contribute to engineering standards, code reviews, and technical decision-making in a fast-paced startup environment STACK & CORE REQUIREMENTS - 5+ years building high-throughput, distributed backend systems; you understand the difference between “working” and “production-grade.” - Strong backend experience in Python (FastAPI preferred), Go, or Java. - Strong command of modern frontend stacks (e.g., React) and ability to build complex, data-dense interfaces. - Deep understanding of modern database design; depth in Postgres and Redis is a strong plus. - Hands-on experience with cloud-native environments (GCP preferred), containers, and Kubernetes. SYSTEM ARCHITECTURE & PRACTICES - Mastery of distributed systems concepts: microservices, idempotency, retry/backoff strategies, and eventual consistency. - Experience with event-driven architectures and high-volume queues (e.g., Kafka, Redis Streams) and caching layers. - You build with observability in mind: metrics, tracing, and logging, and are comfortable working with modern monitoring stacks. REQUIREMENTS ESSENTIAL: - 5+ years of experience as a full stack or backend-heavy engineer working on production systems. - Strong proficiency in at least one of: Python (FastAPI preferred), Go, or Java, including building and operating APIs. - Solid experience with modern frontend frameworks (e.g., React), comfortable building complex, data-dense interfaces. - Strong experience with relational databases and caches; depth in Postgres and Redis is highly valued. - Hands-on experience with cloud-native infrastructure (GCP preferred), Docker, and Kubernetes. - Solid understanding of distributed systems, event-driven architectures, and designing for reliability and scalability. - Comfortable operating in a low-structure, high-ambiguity startup environment with a high degree of ownership. DESIRABLE: - Web3 & privacy: experience with Ethereum/L2s, smart contracts, and especially zero-knowledge proofs (zkSNARKs) for privacy-preserving audit trails. - AI/ML: experience with graph-based models, fraud detection, or anomaly detection on live transaction streams. - Fintech DNA: background in payments, treasury, or other high-audit, regulated environments. - Prior early-stage startup experience and familiarity with rapid iteration and continuous delivery. WHO YOU ARE - First-Principles Thinker: You don't just use tools; you understand why they work. You can reason from the ground up to solve novel problems in hybrid (Fiat/Crypto) finance. - High Velocity: You move extremely fast and thrive in high-ambiguity environments. You ship to learn. - Low Ego, High Output: You care about the product, not the pedigree. You are comfortable switching contexts rapidly—debugging a race condition one hour and designing a new API the next. - Owner Mindset: You don't wait for a ticket. You see a gap, you step in, and you fix it. EQUAL OPPORTUNITIES STATEMENT Tolken is an equal opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees.