Senior Back-End Developer, Engineering (Java / Kotlin)

Echo Base

Portugal Remote contract

Posted: November 7, 2025

Required Skills

Job Description

About Echo Base

Echo Base is a privately funded investment platform focused on special situations and strategic opportunities within the digital asset ecosystem. We acquire, finance, and build companies where our operational expertise and capital can unlock outsized value. Our team combines institutional investment discipline with crypto-native insight to identify and execute on complex opportunities across the industry’s most dynamic segments.

The Role

The Senior Software Engineer is a seasoned professional with at least 6 years of experience in software development. Specialized in finance or crypto within the technology industry, this individual excels in leading problem-solving, driving coding excellence, ensuring comprehensive testing, and adopting scalable and secure software implementations for solutions in areas like trading, swapping, regulatory compliance, fraud detection, automation, and more.

What You'll Do

As a Senior Full Stack Engineer on our core engineering team, you will:

• Take end-to-end ownership of features (backend, API, frontend integration, deployment)
• Design and build new modules (exchange connectors, order routing, wallet / transaction modules, alerts engine)
• Improve, maintain, and scale existing services
• Implement, enforce, and monitor APIs to external crypto exchanges (REST, WebSocket, FIX where applicable)
• Work on state synchronization, caching, rate limits, backpressure, and resilient connectivity
• Ensure system security and correctness (authentication, authorization, encryption, safe handling of keys / wallets)
• Participate in architectural decisions and roadmap planning
• Occasionally interface with DevOps / infrastructure to deploy, monitor, and maintain production services

What We’re Looking For

• A comprehensive grasp of Crypto and Crypto Trading.
• Excellent analytical, critical thinking, and problem-solving skills in financial technology contexts.
• Outstanding testing practices, TDD, unit, integration, e2e testing, (JUnit or similar frameworks)
• Ability to manage, coordinate, and prioritize work with multiple team members for delivering software with quality in time.
• Strong communication skills and an ability to collaborate cross-functionally with product, engineering, and other departments.
• Able to explain technical concepts to both technical and non-technical stakeholders.
• Must be located in the Americas or Europe (between time zones UTC-5 and UTC+3).

• Solid track record of over 10 years demonstrating mastery of Java, Kotlin, Swift, mainly in production applications.
• Solid experience in administration, modeling, optimization techniques in SQL and NoSQL databases.
• Knowledge of software for interface prototyping and wireframing like Figma.
• Understanding of Git and branching models for coordination with team members.

Preferred / Bonus:

• Past experience in crypto / fintech / trading systems
• Experience interacting with blockchain / smart contracts / wallets / DeFi systems
• Experience with FIX, exchange protocols, order routing logic
• Experience with containerization / orchestration (Docker, Kubernetes)
• Experience with CI/CD pipelines, DevOps knowledge
• Experience in microservices / domain-driven design, event-driven architectures
• Experience with high throughput & low latency systems
• Hands-on experience working with release management and architecting within cloud platforms like AWS.
• Familiarity with network security, traffic encryption, and authentication protocols.
• Expertise in utilizing in-memory databases like Redis and Memcached, and processing queues such as Apache Kafka, or RabbitMQ, or standards like AMQP.
• Enhanced skills in other programming languages like Golang and Java are highly valued.

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