Junior Tooling Developer

Crimson7; Belgique; Hybrid; EUR 42,000 - 60,000; Full time

Benefits offered by this job

Hands-on mentorship from senior domain

Real security tooling work shipped to

Job summary

Crimson7 is seeking a Junior Tooling Developer to support R&D of security tooling for offensive and defensive engagements. You will collaborate with senior engineers to build tooling powering Crimson7's security offerings.

The role suits someone with a solid technical foundation, eager to learn, and capable of contributing to real security engagements across finance, defence, and critical infrastructure while joining a collaborative Solution Engineering and Development team.

Qualifications

• Strong proficiency in C# and .NET 9.0.
• Experience building REST APIs with ASP.NET Core.
• Solid understanding of Entity Framework and DbContext, migrations, LINQ.
• Working knowledge of PostgreSQL or similar relational databases.
• Experience with CQRS development pattern.
• Experience with React 18+.
• Experience with TypeScript.
• Knowledge of shadcn/ui and Tailwind CSS.
• Experience with Docker containerization and Dev Containers.
• Familiarity with CI/CD pipelines and GitHub Actions workflows.
• Proficiency with Git version control and branching.
• Ability to read architectural docs for full-stack development.
• Strong problem-solving and teamwork skills.

Responsibilities

• Design and implement RESTful APIs using ASP.NET Core.
• Develop and maintain business logic using the CQRS pattern.
• Write and manage database entities and migrations with Entity Framework.
• Develop frontend features using Next.js (React) with the app router.
• Implement new UI components using the shadcn/ui library.
• Containerize applications using Docker and Docker Compose.
• Maintain CI/CD pipelines with GitHub Actions for automated builds and deployments.
• Participate in code reviews and follow conventional commits.
• Contribute to internal knowledge bases and documentation.
• Ensure secure coding practices and operational discipline.
• Author clear documentation and reports for technical teams.

Skills

C#

.NET

REST APIs

CQRS

React

TypeScript

Reading docs

Problem solving

Team collaboration

Education

Academic background in Computer Science / Cybersecurity

Tools

ASP.NET Core

Entity Framework

PostgreSQL

Next.js

shadcn/ui

Tailwind CSS

Docker

Docker Compose

GitHub Actions

Git

CI/CD

Job description

As a Junior Tooling Developer, you will support the research and development of internal and external security tooling that enables advanced offensive engagements, defensive detection capabilities, and automation of cybersecurity workflows. You will work under senior engineers to build tools that advance Crimson7's offensive and defensive offerings.

This role is ideal for someone with a strong technical foundation, an understanding of both offensive and defensive security principles, and an eagerness to learn and contribute to real security engagements. You will join our Solution Engineering and Development team, working alongside practitioners who deliver Red Teams, Managed Purple Teams, Managed Threat Hunting, and Detection Engineering to clients in finance, defence, and critical infrastructure.

Responsibilities

• Design and implement RESTful APIs using ASP.NET Core
• Develop and maintain business logic using the CQRS pattern (commands, queries, handlers, dispatcher)
• Write and manage database entities and migrations with .NET Entity Framework
• Develop frontend features using Next.js (React) with the modern app router
• Implement new UI components using the shadcn/ui component library
• Containerize applications using Docker and Docker Compose
• Maintain CI/CD pipelines with GitHub Actions for automated builds and deployments
• Participate in code reviews and follow conventional commit standards
• Contribute to internal knowledge bases and documentation
• Ensure development follows secure coding practices and operational discipline
• Author clear documentation and reports for technical teams and stakeholders

Requirements

• Strong proficiency in C# and .NET 9.0
• Experience building REST APIs with ASP.NET Core
• Solid understanding of Entity Framework and the queries it generates (DbContext, migrations, LINQ)
• Working knowledge of PostgreSQL or similar relational databases
• Experience with the CQRS development pattern
• Experience with React 18+
• Experience working in TypeScript
• Knowledge of the shadcn/ui component library and Tailwind CSS
• Experience with Docker containerization and Dev Containers
• Familiarity with CI/CD pipelines and GitHub Actions workflows
• Proficiency with Git version control and branching
• Ability to read and interpret architectural documentation for developing a full-stack application
• Solid problem-solving skills and a willingness to dig into technical challenges
• Good communication skills and the ability to work in a team environment
• Proven capacity to learn fast, adapt to a changing startup environment, and take the leap into growth that may be demanding at the beginning

Nice to Have

• Familiarity with OWASP ASVS (4.0 or 5.0) and OWASP Cheat Sheets
• Familiarity with offensive tools such as Metasploit, Cobalt Strike, or custom C2 frameworks
• Comfortable using artificial intelligence to improve your workflow
• Familiarity with operating system internals (processes, memory, file systems) and the security implications of code behavior
• Experience with coding languages such as C and C++
• Comfortable using debuggers such as x64dbg
• Exposure to security frameworks such as MITRE ATT&CK
• Understanding of defensive detection tooling such as SIEM, EDR, or threat hunting frameworks
• Exposure to Purple Team or Red Team processes
• Experience with cloud-native telemetry (Azure, AWS, GCP)
• Academic background in Computer Science, Cybersecurity, or a related field
• Open-source contributions to security products or published work

What We Offer

A junior developer at Crimson7 helps bridge the gap between cutting-edge threat research and practical tooling that clients use for security validation. You will learn from expert offensive and defensive practitioners while building real tools that contribute to high-impact security outcomes for organizations.

• Hands-on mentorship from senior offensive and defensive engineers
• Real security tooling work that ships to client engagements
• A fast-moving startup environment with room to grow
• Competitive salary and benefits
• Flexible working arrangements for EU-based candidates