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Senior Backend Engineer

Lean Technologies· Engineering
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Sarajevo, BosniaFull-timePosted 4d ago

About the role

Senior Backend Engineer for LeanX, Lean's cross-border and stablecoin business, focused on designing and building scalable backend services and integrations for remittance-related financial products in a fast-moving, high-ownership team.

Responsibilities

  • Design, build, and maintain scalable, high-availability backend services in Java (Quarkus) and Python
  • Build and maintain integrations with external systems - 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 reduction of technical debt over time
  • Review code, set engineering standards, and mentor other engineers on the team
  • Translate product requirements into technical solutions in close collaboration with the Product team
  • Proactively communicate progress, risks, and blockers to the team and stakeholders

Qualifications

  • 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 a microservices architecture
  • Relational databases (PostgreSQL) and caching (Redis)
  • Experience with messaging or event streaming systems (Kafka, RabbitMQ)
  • Strong testing habits (unit and integration) and a 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; pragmatic; proactive communicator; ownership mindset; curious and fast learner; clear English communication

Skills

Required:Java (17+) with QuarkusPythonREST APIsMicroservicesPostgreSQLRedisKafkaSecurity best practices
Nice to have:ClickHouseCrypto/Web3

Benefits

  • competitive salaries
  • private healthcare
  • flexible office hours
  • equity stake for every team member
Last updated Oct 21, 2026. Interested? Apply on the company site.

About Lean Technologies

Open Banking Platform for Banks and Fintechs in MENA

Lean provides the Data and Payments tools to empower MENA's next generation of financial products | Trusted by Etisalat, Hubpay, Lulu Finance, Binance, Sarwa and more.

Open BankingPaymentsFinancial DataFintechBanking
Company profileWebsite

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