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.