Senior Developer
Lumx S.A. is a technology startup that provides infrastructure for payments integrated with stablecoins via APIs. It is not a financial institution but develops smart contracts and technology for clients, which may include payment service providers, banks, fintechs, and FX brokers. Lumx emphasizes compliance with data protection laws, particularly Brazil's LGPD.
About Lumx
From stablecoin on/off-ramps to virtual accounts and wallets, we provide tools for seamless global banking with instant settlements and unmatched liquidity. Streamline global payments, digital accounts, and financial operations with stablecoin-powered solutions. Set up multi-currency, scalable wallets with unique account and routing numbers in a single API call. Transfer funds to bank accounts and wallets with instant settlement and seamless reconciliation. Integrate stablecoins into payment flows, enabling instant settlements, low costs, and real-time access to global liquidity. Design compliant, scalable stablecoin yield products for next-gen finance. Configure fees for extra revenue, monitor performance, and track yields seamlessly. We leverage our direct banking relationships to offer seamless FX operations with the best rates and deep liquidity, directly minting USDC/EURC and avoiding intermediary spreads. Our APIs are designed to be intuitive, secure, and versatile, supporting a wide range of financial operations. Focus on growing your business while we handle smart contract audits, orchestration, and all the technical, operational, and compliance upkeep. Lumx S.A. is a startup specializing in providing technological infrastructure for payments integrated with stablecoins through Application Programming Interfaces (APIs). The company acts as a Controller of personal data, determining the purpose and methods of processing as described in its Privacy Notice, ensuring lawful and transparent processing in accordance with Brazilian legislation. Lumx collects personal data from various sources, including directly from data subjects via its website, social media interactions, job applications, and event registrations, as well as from third parties like clients' legal representatives and end-users to perform services. The data collected includes contact details, academic and professional history, identification data, and financial data like wallet addresses and PIX keys. Lumx is a technology and smart contract development company and is not a broker-dealer or financial institution.
Skills
About the Role
You will design, build, and operate mission-critical backend services that power pay-ins, pay-outs, and currency conversion. You will integrate banks, PSPs, and FX providers through high-quality connectors, run reliable event-driven workflows and long-running sagas, and ensure precise reconciliation and amount semantics. You will implement idempotency, retries, dead-letter handling, observability, and recovery strategies, and write clear runbooks and ADRs while mentoring peers through reviews and technical guidance.
Requirements
- 5+ years building backend services at scale with fintech payments or FX experience
- Strong TypeScript and Node.js fundamentals
- Design and implement high-quality REST JSON APIs
- Deep understanding of event-driven architecture queues and streams
- Experience with saga patterns and function-orchestrated workflows (experience with Temporal.io is a plus)
- Relational data modeling and PostgreSQL expertise
- Knowledge of transactions consistency and performance tuning
- Caching strategies
- Security mindset for financial systems and familiarity with regulated environments including KYC KYB and KYT concepts
- Experience with FX rate-locking treasury and reconciliation at multi-entity scale
- Knowledge of local rails such as PIX and ACH cards and crypto on/off-ramps
Responsibilities
- Integrate partners by shipping connectors with banks PSPs and FX providers
- Design and run services for pay-ins pay-outs and FX including quoting rate-locking execution netting and settlement
- Implement idempotency retries backoff dead-letter queues and graceful degradation
- Orchestrate event-driven workflows and long-running sagas for multi-party financial processes
- Ensure reconciliation and correct amount rounding semantics across entities
- Document architecture decisions and runbooks and mentor team members through code reviews
Benefits
- Competitive compensation and potential equity
- Remote-friendly with flexible hours (Americas time zones)
- Learning budget for conferences and courses
- Local holidays and supportive time-off policy