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LeanX, part of Lean Technologies, is expanding its financial products beyond remittance into embedded wallets, corporate solutions, and cross-border stablecoin infrastructure. As a Senior Backend Engineer, you will design and build the backend systems and integrations powering these products in a small, high-ownership team operating in Sarajevo.
Lean is the leading financial infrastructure provider in the Middle East, trusted by 450+ clients including Tabby, Hungerstation, and Binance. The company has processed billions of dollars in transactions and is backed by General Catalyst, Sequoia, and Shorooq. LeanX specifically operates as Lean's cross-border and stablecoin business, serving remittance companies, exchange houses, and businesses moving money across borders.
In this role, you will:
- Design, build, and maintain scalable, high-availability backend services in Java (Quarkus) and Python
- Build and maintain integrations with external systems including payment providers, exchanges, banks, blockchain networks, ClickHouse, and identity services
- Own the reliability, security, and consistency of transactions and financial data across systems
- Drive performance improvements, architecture decisions, and technical debt reduction
- Review code, set engineering standards, and mentor other engineers
- Translate product requirements into technical solutions in collaboration with the Product team
- Proactively communicate progress, risks, and blockers to the team and stakeholders
You will work on systems handling high-throughput, low-latency, and high-availability requirements in a regulated fintech environment. The role sits at the heart of unlocking a $50B+ addressable market across the MENA region.
Compensation includes competitive salaries, private healthcare, flexible office hours, and meaningful equity stakes for all team members to ensure long-term alignment.
REQUIREMENTS:
- 5+ years building and running backend systems in production
- Strong Java (17+) with a modern framework (Quarkus); solid hands-on Python
- Experience designing REST APIs and working in microservices architecture
- Solid knowledge of relational databases (PostgreSQL) and caching (Redis)
- Experience with messaging or event streaming systems (Kafka, RabbitMQ)
- Strong testing habits (unit and integration) and track record of rigorous code review
- Security-aware engineering: authentication, secrets handling, and secure coding practices
- Experience building and operating high-throughput, low-latency, or high-availability systems
- Familiarity with ClickHouse or other analytical databases
- Crypto or blockchain product experience: wallets, exchanges, custody, on-chain data, or interacting with nodes (Web3j, web3.py)
- Understanding of cryptography fundamentals: key management, signing, HSMs
- Fintech, payments, or regulated environment background (KYC/AML, compliance)
- Calm and delivery-focused under pressure; drives tasks to completion and raises blockers early
- Pragmatic approach balancing quality with speed
- Proactive communicator with reliable status and risk reporting
- Takes ownership of outcomes including mistakes
- Curious and fast learner; picks up new tools, technologies, and domains quickly
- Clear communication in English
