# Senior Backend Engineer at LeanTech > Bosnia and Herzegovina · Senior · Backend · open. Source: https://alderhq.app/jobs/ashby%3ALeanTech%3Ad6e9e08a-b380-4af0-ab02-8e536379f5c3 (read 2026-11-10). ## Facts (observed) - Company: [LeanTech](https://alderhq.app/companies/leantech) - Location text: Sarajevo, Bosnia - Where it can be done from (inferred): Bosnia and Herzegovina (evidence: "Location: Sarajevo, Bosnia") - Posted: 2026-10-19 (22 days ago) - First seen by alder: 2026-11-07 · last verified: 2026-11-08 - Reposted: 0 times · edited: 0 times - Apply on the employer's site: https://jobs.ashbyhq.com/LeanTech/d6e9e08a-b380-4af0-ab02-8e536379f5c3 - Skills listed (inferred): Python, Java, PostgreSQL, Redis, Kafka, Distributed systems ## Pay and sponsorship - Posted pay: not posted ## Description (the employer's text) ### 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 Lean Lean is the leading financial infrastructure provider in the Middle East. We power some of the region's largest companies with APIs that enable payments, account verification, financial data access, and other critical financial infrastructure. What started as the region's pioneering Open Banking platform and quickly became the de facto leader in account aggregation and payment initiation in the region is now becoming something bigger: a multi-product infrastructure company powering payments, data, and lending across MENA. We've processed billions of dollars in transactions. We're trusted by 450+ clients - from Tabby and Tas'heel to Hungerstation - and backed by General Catalyst, Sequoia, and Shorooq. Our $67.5M Series B was just the beginning. We're expanding into new markets, opening offices, acquiring businesses, and building capabilities that didn't exist here before. About LeanX: LeanX is Lean's cross-border and stablecoin business. Our clients are remittance companies, exchange houses and businesses moving money across borders, mostly for person-to-person remittance and business payouts. LeanX operates under Lean's regulated entities and is built by a dedicated engineering team in Sarajevo. ### 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 --- Data: alder (https://alderhq.app). Cite https://alderhq.app/jobs/ashby%3ALeanTech%3Ad6e9e08a-b380-4af0-ab02-8e536379f5c3 and the date you read it. Observed facts come from the employer's own listing; location reach, level, family and skills are inferences.