Senior Go Developer

Who we are

CryptoNext Security is a deeptech startup specializing in post-quantum cryptography. Our solutions help businesses and institutions prepare for a future where quantum computers will challenge traditional data security. We work with leading clients in finance, defense, and telecommunications.

• Build and maintain, in Go, the connectors that link CryptoNext Platform to our clients' tools (CLM, CMDB...): extracting, normalizing and exposing data through REST APIs.
• Consume heterogeneous third-party APIs: handle pagination, rate limits, retries, idempotency and provider outages.
• Design and evolve the API contracts exposed to CryptoNext Platform: OpenAPI and versioning.
• Model and query PostgreSQL, use Redis, and process work asynchronously through RabbitMQ.
• Containerize your deliverables (Dockerfile, Docker Compose) and get your changes through GitLab CI.
• Instrument your services (logs, metrics, traces), diagnose incidents in staging and production, and contribute to root cause analyses.
• Write the unit and integration tests that back your features, including against test doubles of provider APIs, and give QA what they need to automate the rest.
• Review code and help onboard new team members.
• Work directly with Product and QA.
• Use AI coding tools as leverage under your own judgement, staying accountable for what lands in the repo.
• Propose architecture changes and refactorings, and explain the trade-offs you accepted.

How we work

A team of six engineers, within our 15-person R&D department. Connectors live in a monorepo and follow a hexagonal architecture. Three days a week in our Paris office, the rest remote. Short feedback loops, high standards. We ship a working version early rather than polishing in isolation, and keep solutions as simple as the problem allows.

The skills you'll need

• Production Go: concurrency (goroutines, channels), context, explicit error handling, interfaces, modules and standard tooling (go test, go vet).
• Hexagonal architecture (ports and adapters), or the ability to defend an equivalent split.
• Third-party API integration: robust HTTP clients, timeouts, retries with backoff, pagination, rate limiting, idempotency.
• Asynchronous processing: RabbitMQ consumers, acknowledgements, retries and failure handling, dead‑lettering, backpressure.
• PostgreSQL: schema design, migrations and rollbacks, indexing, reading a query plan. Hands-on use of Redis.
• API contract design: REST, OpenAPI, versioning.
• Unit and integration testing, with a defensible position on what belongs at which level and on what is worth testing at all.
• Delivery: Docker and Docker Compose, GitLab CI.
• Operations: observability and incident diagnosis.
• Real use of AI‑assisted development in a production codebase: agentic workflows, context management, reviewing generated output as critically as a colleague's merge request. You have a view on where these tools pay off and where they create debt.
• Experience means you can say why you chose an approach, what you rejected, and what it will cost in six months.

Bonus skills

• Java.
• Knowledge of the CLM/PKI (X.509 model) and CMDB domains.
• Knowledge and hands-on handling of provider authentication schemes: OAuth2, mTLS, API keys.
• Secure coding practices and application security.
• Experience in a startup or deeptech environment.

Benefits

• A stimulating work environment with cutting-edge technological challenges.
• A competitive salary, aligned with our compensation philosophy.
• A deep dive into the exciting world of post-quantum cryptography and cybersecurity.

The team you'll be joining

You will join a team of six engineers who own their features across the whole stack, inside our 15-person R&D department, working closely with Product and QA. You will report to the Head of Engineering and collaborate with other departments to build the backend services and interfaces our clients depend on.