Senior Backend Engineer - Crypto & Financial Infra

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

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.