Senior Elixir Engineer

Ready to embark on the quest of joining Hack The Box?

Welcome! Super excited you dropped by

At the end of this journey, you'll become a proud member of Hack The Box, with the ultimate mission to raise cyber resilience, so that every organization can stay ahead of tomorrow’s threats.

The core mission of the Senior Elixir Engineer:

Join our fast-growing team building the platform that trains the world's cyber workforce. As a Senior Elixir Engineer, you'll own backend and full-stack feature delivery on Phoenix and LiveView — designing resilient OTP systems, clean APIs, and real-time user experiences that scale to millions of users.

Our culture prizes autonomy, technical craft, and the drive to ship secure software that outsmarts attackers.

The fellowship you’ll be joining:

Reporting to the VP of Artificial Intelligence, you will be part of a 7 people team. You'll collaborate with product, design, and security researchers to turn complex detection and response workflows into intuitive, intelligence-driven user experiences—while mentoring engineers and shaping our technical roadmap.

Location & Work Mode:

• Europe/Greece
• Choose between fully remote work across Europe or relocating to our Athens Tech Hub with relocation support.

Fully Remote / Hybrid (2 days in the office, 3 days remote, plus one month of work from anywhere) - If only in Greece: When hiring in Greece, we’re open to candidates from all locations. Those based within 55 km of our Athens office will follow a hybrid work model. For candidates located beyond that radius, a fully remote arrangement is available.

Relocation

• We offer a 10% relocation bonus on the annual salary to support your move.
• In addition, you would benefit from a 50% tax reduction on your income as part of the relocation.
• We'll support you with accommodation during the first few weeks

Technology tools & weapons you’ll be using:

• Elixir / Erlang / OTP
• Phoenix, Phoenix LiveView, Phoenix PubSub
• Ecto & PostgreSQL
• Oban (background jobs)
• Tailwind CSS, LiveView JS hooks
• Telemetry, Prometheus, Grafana, Sentry
• Docker, Kubernetes, GCP

The adventures that await you after becoming Senior Elixir Engineer at Hack The Box:

• Design and build production Phoenix applications — REST APIs, LiveView UIs, and real-time features on PubSub and Channels.
• Model and evolve data with Ecto and PostgreSQL, writing performant queries and safe, zero-downtime migrations.
• Build fault-tolerant systems with OTP: supervision trees, GenServers, and distributed BEAM patterns where they earn their keep.
• Own background processing and scheduled workloads with Oban, with proper observability via Telemetry and metrics.
• Ship secure-by-default code: authentication/authorization patterns, least-privilege data access, and input hardening — this is a security company.
• Deploy and operate services on Kubernetes/GCP, contributing to CI/CD pipelines and release quality.
• Mentor engineers and contribute to technical leadership through code reviews, design sessions, and coding standards.
• Document decisions and communicate clearly in a remote-first environment, contributing to a culture of thoughtful async collaboration.

Skills, knowledge, and experience points required to unlock the role of Senior Elixir Engineer at Hack The Box:

• 5+ years of professional backend or full-stack development, with 3+ years shipping production Elixir/Phoenix.
• Strong grasp of OTP and the BEAM — processes, supervision, GenServer/GenStage, and when not to reach for them.
• Hands-on experience building interactive UIs with Phoenix LiveView (components, streams, JS hooks).
• Deep Ecto and PostgreSQL knowledge: schema design, query optimization, indexing, migrations.
• Experience with background job systems (Oban preferred) and event-driven architectures.
• Solid testing discipline with ExUnit; comfortable with property-based and integration testing.
• Familiarity with containerized deployment (Docker, Kubernetes) and CI/CD best practices.
• Security-minded engineering: OWASP fundamentals, auth patterns, secure handling of user data.
• Excellent written & verbal communication, especially in remote/async environments, with a bias toward documenting architecture and decisions.

What your Hack The Box adventure will have in store:

• You'll have the exhilarating opportunity to contribute to a product that is highly appreciated by users and the cybersecurity community at large.
• You'll experience a highly supportive and caring environment, fostering growth, flexibility, and autonomy.
• You'll embark on an exciting journey of continuous learning and problem-solving, levelling up as our organisation grows.
• Most importantly, you'll have a blast at HTB because fun is an essential ingredient in our recipe for success! Just wait until you see our global meet-ups!

The gems you’ll be enjoying as Senior Elixir Engineer:

• 25 annual leave …