Lean Technologies logo - Senior Backend Engineer

    Senior Backend Engineer

    Lean Technologies
    Sarajevo, Federation of Bosnia and Herzegovina, Bosnia and Herzegovina
    Full-time
    Engineering
    Apply Now

    About the role

    LeanX (Part of Lean) is quickly expanding beyond remittance into a new generation of financial products, from embedded wallets to corporate, and this role sits at the heart of that expansion. The ideal candidate brings experience in crypto or blockchain products, such as a good understanding of wallets, exchanges, custody, on-chain movements, and the ecosystem in general.

    As a Senior Engineer, you will design and build the backend systems and integrations that power these products, working in a small, high-ownership team that moves fast and ships real things. Your work will directly determine how quickly LeanX (Part of Lean) can unlock a $50B+ addressable market across the region.

    About LeanX (Part of Lean)

    LeanX is Lean Technologies' cross-border payments platform. It helps banks, exchange houses, money transfer operators and payroll platforms send money internationally, with 24/7 settlement and local-currency payouts.

    Traditional cross-border payments run through correspondent banks, so they're slowed down by cut-off times, weekend queues and cash sitting idle in nostro accounts. LeanX gets rid of that. Clients use one API and one counterparty instead of separate banking setups in every market.

    LeanX sits within Lean, the leading financial infrastructure provider in the Middle East, trusted by 350+ clients including Binance, Careem, and Etisalat, and backed by General Catalyst, Sequoia, Bain, and more. Lean has processed billions of dollars in transactions and raised over $100M to date. LeanX is one of its most profitable and fastest-moving bets - a small team with a very large mandate.

    What you'll own

    • 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

    What we're looking for

    • 5+ years building and running backend systems in production

      • Strong Java (17+) with a modern framework - we use Quarkus; solid hands-on Python

      • Experience designing REST APIs and working in a 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 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 - you drive tasks to completion, raise blockers early, and don't wait to be chased

      • Pragmatic: you balance quality with speed and know when "good enough" ships

      • Proactive communicator: you report reliably on status and risks in writing and stand-ups

      • Takes ownership of outcomes, including mistakes, and follows through

      • Curious and a fast learner. You pick up new tools, technologies, and domains quickly

      • Clear communication in English

    NB. While we think the above experience could be important, we're keen to hear from people that believe they have valuable experience to bring to the role. If you identify with the team and mission, but not all of our requirements, then please still apply!!

    Why Join us?

    We're building the financial infrastructure for MENA. Not as a slogan, as a fact.

    Since 2019, we've become the first regulated Open Banking and Open Finance company operating across the UAE and Saudi Arabia. We've processed billions of dollars. We connect millions of accounts. We enable companies like Binance, Careem, and Etisalat to build products that were previously impossible in this region.

    Our recent $67.5M Series B from General Catalyst and Sequoia isn't just validation: it's fuel. We're expanding into new markets, launching new products, and setting the pace for what financial innovation looks like in MENA.

    We solve hard problems. We move fast. We hold ourselves to a high standard. And we're looking for people who've done this before to help us do it right.

    If you're motivated by building something that lasts, not just something that scales, Lean is where you need to be.

    Not only do we offer competitive salaries, private healthcare, and flexible office hours, but we also insist that every member of the team hold a meaningful equity stake in the business to ensure long-term alignment. We'd love you to join us for this journey!

    Lean is proud to be an equal opportunity workplace and is an affirmative action employer. We are committed to equal employment opportunity regardless of race, color, ancestry, religion, sex, national origin, sexual orientation, age, citizenship, marital status, disability, gender identity or Veteran status.

    When applying for a job at Lean Technologies, we will need to collect, use and share Personal Data about you with different members of our team during the application process. This may mean transferring your data to members of the team in one of our office locations worldwide outside of the country you are in. Please refer to our Privacy Notice on our website for more information about how we may use and store your Personal Data

    Ready to Apply?

    To submit your application for this position, please visit Lean Technologies's official website and follow their application process.

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