Backend Software Engineer (m/f/n)

Currently, for one of our Partners, a European Union Organisation based in Brussels, we are looking for an experienced Backend Software Engineer (m/f/n) to join a long-term international project.

• At least 10 years of experience as a Backend Software Engineer on IT projects.
• Minimum 4 years developing Verifiable Credential solutions.
• At least 2 years developing Verifiable Credentials in content protection.
• Minimum 5 years experience in blockchain and/or distributed ledger technology development.
• At least 5 years experience developing Web3-based systems.
• English language proficiency at minimum B2 level (CEFR).
• At least 10 years in back-end programming including Go, C++, and server-side frameworks such as Node.js.
• At least 10 years working with application performance monitoring tools like Dynatrace, Splunk, Elastic APM, and OpenTelemetry.
• Minimum 7 years experience with relational databases such as PostgreSQL, Oracle, MySQL, and NoSQL databases like MongoDB, CouchDB, CosmosDB.
• At least 7 years experience with version control workflows including GitFlow, trunk-based development, and legacy systems using SVN.
• Minimum 7 years designing, developing, and securing RESTful APIs and web services including OpenAPI/Swagger.
• Minimum 7 years with containerisation and orchestration technologies like Docker and Kubernetes.
• At least 4 years with authentication and authorisation standards (OAuth 2.0, OpenID Connect, W3C VCDM, DIDs, SD-JWT) and 2 years defining digital signature profiles.
• At least 4 years in cryptographic concepts including public/private key cryptography, digital signatures, hashing, key management, and secure key storage.
• Minimum 5 years developing applications for blockchain and distributed ledger technologies, smart contract interactions, event-driven architectures, with at least 3 years using Ethers.js and web3 integrations.
• At least 1 year experience with Zero-Knowledge Proofs (ZKP) for privacy-preserving proofs.

• Design, develop, and maintain robust, secure, and scalable back-end applications and services.
• Design and implement server-side business logic integrating front-end components and external systems.
• Design, implement, and optimise data storage solutions ensuring data integrity, performance, and scalability.
• Develop and maintain secure RESTful APIs and web services following best practices.
• Apply secure software engineering principles including authentication, authorisation, and secure data storage.
• Optimise applications for performance, scalability, resilience, and operational efficiency.
• Contribute to scalable software architectures and distributed systems design.
• Produce clean, maintainable, reusable, and well-documented code.
• Analyse application logs and metrics to identify issues and improve system performance.
• Develop and maintain automated unit and integration tests.
• Diagnose and resolve software defects ensuring quality through testing.
• Deliver software meeting security, performance, availability, maintainability, and usability requirements.
• Produce and maintain technical documentation including design specs and API docs.
• Configure and integrate cloud-native services including serverless computing, storage, and container orchestration.
• Develop business services using modern back-end languages and frameworks.
• Implement robust authentication, authorisation, and identity management mechanisms.
• Contribute to CI/CD pipelines with automated testing and deployment.
• Design and maintain highly secure and scalable blockchain and Web3 solutions.
• Define technical architecture of decentralised applications and smart contract ecosystems.
• Design and optimise smart contract systems on EVM-compatible networks.
• Design blockchain-based tokenisation models and manage lifecycle of digital assets.
• Define and implement cryptographic protocols including digital signatures, Zero-Knowledge Proofs, and privacy mechanisms.
• Design decentralised identity solutions using Decentralised Identifiers, Verifiable Credentials, and OpenID4VC.
• Define blockchain interoperability architectures integrating with enterprise and cloud systems.
• Design event-driven architectures integrating blockchain events with off-chain services.
• Optimise blockchain applications for security, gas efficiency, and scalability.
• Perform smart contract security reviews and support formal verification.
• Design blockchain data indexing services using Subgraph, GraphQL, or equivalents.
• Lead evaluation and adoption of emerging blockchain protocols and Web3 technologies.
• Contribute to blockchain governance models and engineering best practices.
• Provide technical leadership, mentoring, architecture and code reviews.
• Produce high-quality technical documentation including architecture and security analyses.

Services must be performed from within the European Union. Two physical meetings with the customer are planned per 12-month period, maximum 2 days each, at contractor’s cost.