Java Software Engineer
@ APX (Now Aster)

Hybrid
$130,000
Hybrid
Full Time
Posted 23 days ago

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XXXXXXXXX XXXXXXXXX XXXXXX****** @aster.com
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Job Details

Overview

The Java Software Engineer at APX (Now Aster) will architect and optimize backend systems for blockchain data processing, build high-performance APIs, implement off-chain logic for DeFi applications, and develop microservices to improve wallet interactions and transaction queuing.

Main Responsibilities

  • Architect and optimize backend systems for blockchain data (indexing, RPC interactions, event streaming).
  • Build high-performance APIs for frontends and smart contracts using REST, WebSocket, and GraphQL.
  • Implement off-chain logic for DeFi apps including price oracles and risk engines.
  • Develop microservices for wallet interactions, transaction queuing, and gas optimization.
  • Ensure reliability of critical infrastructure through node management, load balancing, and failover systems.
  • Collaborate with smart contract developers on protocol integrations.

Required Skills and Experience

  • 3+ years of backend development using Java (also Rust, TypeScript, Go).
  • Experience with blockchain technologies (JSON-RPC, ethers.js/web3.py, transaction lifecycle).
  • Expertise in database optimization (PostgreSQL, TimescaleDB, Redis).
  • Familiarity with asynchronous architectures (Kafka, RabbitMQ, Celery).
  • Solid knowledge of the Web3 stack, including EVM and indexers.
  • Understanding of security practices such as rate limiting, sanitization, and replay protection.
  • Cloud deployment experience with AWS/GCP, containerization, and Infrastructure as Code (IaC).

Key skills/competency

Java, blockchain, backend, microservices, APIs, cloud, security, async, database, integration

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How to Get Hired at APX (Now Aster)

🎯 Tips for Getting Hired

  • Customize your resume: Tailor skills for blockchain and backend engineering.
  • Highlight relevant experience: Emphasize Java and microservices projects.
  • Connect on LinkedIn: Engage with APX (Now Aster) professionals.
  • Prepare for technical interviews: Review blockchain and API design nuances.

📝 Interview Preparation Advice

Technical Preparation

Review Java concurrency techniques.
Practice API design and RESTful services.
Study blockchain JSON-RPC integration.
Refresh cloud deployment on AWS/GCP.

Behavioral Questions

Describe your teamwork in complex projects.
Explain a challenging problem solved.
Share a time you optimized system performance.
Discuss how you manage tight deadlines.

Frequently Asked Questions