Senior Software Engineer

Who you are

• 5+ years of backend software development experience, with a proven track record of building and operating high-availability, large-scale applications
• Strong engineering fundamentals — data structures, algorithms, concurrency, and software design patterns — and the judgment to know when to reach for which
• Ownership instinct. You take responsibility for outcomes, not just tickets. When something's broken or unclear, you move toward it
• Ability to drive cross-team collaboration, managing complex dependencies and competing requirements without losing momentum
• Excellent problem-solving skills, and comfort operating with autonomy in a fast-paced environment
• Strong written and verbal communication. You can explain a complex technical trade-off to an engineer and to a non-technical stakeholder, and land it with both
• Genuine interest in crypto or fintech, and in building things that make money move better

What the job involves

• We're looking for a Senior Software Engineer to join our Payments Team, based in the US. Payments is where OKX meets the real financial world. Our team has built and operates the infrastructure connecting OKX to dozens of payment channels across global markets, giving users deposit and withdrawal options that are fast, convenient, and — most importantly — trustworthy. That platform moves and safeguards user assets at institutional scale, continuously, across time zones and regulatory environments
• This is not a greenfield team looking for its footing. The team is established, the platform is in production at scale, and we are actively expanding — both in scope and in headcount. That combination is rare: you get the leverage of joining a growing team where your work visibly shifts the roadmap, along with the discipline that comes from a system already trusted with real money
• It's also an unusually good place to learn. Payments is a domain that's hard to pick up from the outside — every market has its own rails, its own settlement behavior, its own failure modes, its own compliance expectations. Here you'll work across a wide range of payment methods and channels, and you'll build the judgment that comes from operating financial systems where the stakes are real: how to design for correctness when money is on the line, how to reconcile, how to recover, how to keep a platform observable enough that you find problems before your users do
• You'll work closely with product managers, designers, and partner-facing teams, and you'll set the technical bar for the engineers around you — through design docs, code reviews, and the everyday habit of doing things properly when nobody's watching
• If you like the sound of a team where the problems are genuinely hard, the standard is high, and your opinion changes the outcome, we'd like to talk
• Design and build the core. Develop high-scale, 24/7 APIs and distributed payment services across multiple cloud providers, using Java and Spring Boot as the primary stack. Own systems end to end — from design doc through production ownership
• Expand our global reach. Help integrate and scale new payment channels and methods across markets, each with its own technical, operational, and reliability characteristics
• Protect user assets. Build for correctness first: consistency, idempotency, reconciliation, failure recovery, and the operational tooling that lets us stand behind every transaction
• Set the technical bar. Participate actively in design and code reviews, giving and receiving direct, constructive feedback. Help evolve the standards a growing team builds on
• Solve the hard problems. Investigate complex distributed-systems challenges and drive them to resolution rather than handing them off
• Partner across functions. Work with product, design, and partner teams across regions to turn ambiguous requirements into shipped systems, and to unblock dependencies before they become delays
• Grow the team's capability. Mentor engineers and share what you learn. Seniority here is measured in leverage, not just output
• Stay curious. Keep pace with a fast-moving industry and bring the good ideas back
• What you'll take away from this role
• Deep, practical fluency across a wide range of global payment methods and channels — knowledge that is genuinely hard to acquire anywhere else
• Experience designing and operating systems entrusted with substantial user assets, where correctness and recoverability are non-negotiable
• A track record of shipping in a regulated, high-stakes domain at real scale