Senior Backend Engineer

Lean; United States; On-site; USD 150,000 - 210,000; Full time

Benefits offered by this job

Competitive salaries

Private healthcare

Flexible office hours

Meaningful equity stake

Job summary

LeanX, part of Lean, is expanding beyond remittance into a new generation of financial products. As a Senior Engineer, you will design and build scalable backends in Java (Quarkus) and Python, integrating with payment providers, exchanges, banks, and blockchain networks to power wallets and on-chain movements.

You will own reliability and security of financial data, drive architectural decisions, and mentor teammates in a fast-paced, high-ownership environment across MENA-region markets.

Qualifications

• 5+ years building and running backend systems in production.
• Strong Java (17+) with a modern framework (Quarkus); solid Python.
• Experience designing REST APIs and working in a microservices architecture.
• Solid knowledge of PostgreSQL and Redis caching.
• Experience with messaging or event streaming systems (Kafka, RabbitMQ).
• Strong testing habits (unit/integration) and rigorous code review.
• Security-aware engineering: authentication, secrets handling, 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.

Responsibilities

• Design, build, and maintain scalable backend services in Java (Quarkus) and Python.
• Build and maintain integrations with external systems (payment providers, exchanges, banks, blockchain networks, ClickHouse, identity services).
• Own reliability, security, and consistency of transactions and financial data across systems.
• Drive performance improvements and reduce technical debt over time.
• Review code, set engineering standards, and mentor engineers on the team.
• Translate product requirements into technical solutions with Product team.
• Proactively communicate progress, risks, and blockers to team and stakeholders.

Skills

Java (17+)

Python

REST APIs

Microservices

PostgreSQL

Redis

Kafka/RabbitMQ

Testing (unit/integration)

Security

High-throughput systems

ClickHouse

English communication

Tools

Quarkus

web3.py

Web3j

ClickHouse

Job description

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

  • 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.

• competitive salaries
• private healthcare
• flexible office hours
• meaningful equity stake

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.

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