Lead Junior Freelance Junior Senior Software Engineer Node 2c Javascript Sdk in Amsterdam

About BlockTech BlockTech is a fast-paced algorithmic trading firm facilitating global cryptocurrency derivatives and spot trading while expanding into new markets. As we continue to grow rapidly, we are looking for a Senior Software Engineer to take technical ownership of our Core systems and help shape how they evolve through our scale-up phase. This is a role for an engineer who has already built and operated correctness-critical systems at scale and who wants their technical decisions to set direction, not just follow it. What will you do? You will own the systems that keep our trading operation accurate at every level — positions, PnL, instruments, hedging, and the data flowing between them. Across exchanges and asset classes, your work determines whether the numbers our traders and risk team rely on are correct. As a senior engineer, you will also set the technical standards the rest of the team builds against. You will: Own the books. Maintain and evolve our position, trade, and PnL systems so they remain accurate across every venue. Architect the platform that supports trading. Design services that handle real-time exchange flow with the throughput and reliability our quoting and hedging depend on, making the structural calls that keep them fast and correct under load. Own the data flows. Operate and harden the public and private pipelines bringing market prices, account state, and trade events into our systems in real time. Lead venue integrations end-to-end. Deliver exchange and prime-broker integrations across protocol, account model, settlement, reconciliation, and surveillance and define the patterns we reuse for the next one. Model the instrument universe. Own the systems describing every tradable instrument - lifecycle, expiry, margin, RFQs, fast-path quoting - where both correctness and latency matter. Build self-healing systems. Design the detection and repair flows that identify position discrepancies and correct them automatically. Own hedging inf