Staff Software Engineer (Payments) in London

Location: New York, United States • London, United Kingdom (Office)

On-Site | Full-time

Compensation: Competitive Compensation

Our client is a high-growth software development company and a major contributor to one of the largest and fastest-growing crypto social networks globally. Operating in a high-velocity, high-impact environment, the organization builds cutting-edge infrastructure that supports massive global transaction volumes and substantial revenue generation.

The organization is seeking a Staff Software Engineer (Payments) to design and build the core payment services at the center of this ecosystem. This is a senior, high-ownership role designed for an engineer who thrives on solving hard, ambiguous problems end-to-end—from the moment money enters the system to final settlement, reconciliation, and delivery.

Operating within a lean team of highly experienced engineers, the successful candidate will focus on 0→1 development, moving quickly while maintaining the absolute rigor required for financial systems. The engineering culture prioritizes low bureaucracy, continuous production deployment, and trust in individual judgment over rigid processes.

• End-to-End Ownership: Take full ownership of complex payment infrastructure challenges, carrying projects from initial architectural design through to production implementation and on-call support.
• Core Payment Services: Design, build, and optimize high-performance, mission-critical systems governing money movement, transaction processing, and ledgers.
• System Architecture: Develop resilient distributed systems using asynchronous and event-driven patterns, ensuring fault tolerance, strict consistency models, and exactly-once semantics.
• Data Integrity & Security: Implement robust database strategies, transaction management, and security protocols, ensuring absolute data correctness, key management hygiene, and comprehensive audit trails.
• Continuous Delivery: Ship high-quality code to production continuously, balancing a bias for action with the deliberate precision required for financial infrastructure.

• Core Qualifications
• Strong Backend / Systems Engineering: Proven track record of building high-performance, critical infrastructure. Deep experience in Rust is highly advantageous, but strong engineers from other systems backgrounds (such as Go, C++, or Java/Scala) who can rapidly adapt to Rust will be fully considered.
• Distributed Systems Expertise: Thorough understanding of consistency models, idempotency, fault tolerance, and sagas, with experience designing systems that remain correct under partial failure conditions.
• Financial or Transactional Rigor: Prior experience in payments, fintech, high-throughput transaction processing, or another domain where system correctness is vital and 'mostly works' is unacceptable.
• Advanced Database Fundamentals: Deep knowledge of transactions, indexing, query/caching strategies, event streaming, and a strong respect for auditability and reconciliation.
• Security-First Instinct: Natural adherence to secure engineering practices, including secrets hygiene, least-privilege access, and maintaining clean audit trails.
• Autonomy & Leadership: Ability to make high-impact technical decisions independently, navigate ambiguity comfortably, and execute both high-level design and necessary reliability work.

• Deep Rust experience, open-source contributions, or performance optimization skills (profiling, reducing allocations, lock-free structures).
• Domain depth in payment rails (card networks, bank rails, chargebacks, open banking) or accounting fundamentals (double-entry ledgers, regulatory reporting).
• Experience building risk, fraud, or compliance infrastructure (rule engines, device fingerprinting, sanctions screening, KYC/AML workflows).
• Familiarity with crypto, Web3, or on-chain infrastructure (wallet infrastructure, stablecoin flows).
• A background in platform engineering, cloud infrastructure, or observability.

• Competitive Compensation: Highly competitive base salary.
• Equity & Upside: Generous equity and token allocation, offering direct alignment with the long-term growth and success of the platform.
• High Autonomy: A culture that trusts professional judgment, providing the freedom to make critical decisions without layers of bureaucratic approval.
• Impact: The opportunity to build core infrastructure for a globally dominant platform shaping the future of digital interaction and decentralized finance.

• Recruiter / HR Screening Call
• Founder / CEO Interview
• Initial Technical Interview
• Final Technical Interview

Due to the high volume of applications we anticipate, we regret that we are unable to provide individual feedback to all candidates. If you do not hear back from us within 4 weeks of your application, please assume that you have not been successful on this occasion. We genuinely appreciate your interest and wish you the best in your job search.

At MLabs, we are committed to offer equal opportunities to all candidates. We ensure no discrimination, accessible job adverts, and providing information in accessible formats. Our goal is to foster a diverse, inclusive workplace with equal opportunities for all. If you need any reasonable adjustments during any part of the hiring process or you would like to see the job-advert in an accessible format please let us know at the earliest opportunity by emailing human-resources@mlabs.city.

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