Senior JavaScript Security Researcher

Who are we? Want your JavaScript security research to protect millions of users from real-world fraud and emerging browser-based threats? Join ThreatFabric as Senior JavaScript Security Researcher and turn cutting-edge browser research into detection capabilities used by leading financial institutions worldwide.

We help the world's leading banks stay ahead of fraudsters, scammers, and cybercriminals. Our technology protects millions of users every day by detecting fraud, malware, and emerging attack techniques before damage is done. We do this by combining 15 years of extensive research with our own smart software.

At ThreatFabric, we're not just shaping the future of cybersecurity - we're defining it. With our headquarters in the vibrant city of Amsterdam, ThreatFabric stands at the forefront of combating online fraud, mobile malware, and threat intelligence. Your mission Position: Full-time | 40 hours per week
Location: Amsterdam, Netherlands | Work From home (2-3 days per week in the office)
Salary Range: 80.000,- to 100.000,- annually

The position
As a Senior JavaScript Security Researcher, you'll explore new browser capabilities, uncover detection methods, and turn cutting-edge research into real-world protection used at global scale. Your discoveries won't remain on a whiteboard, they'll directly help safeguard people and businesses around the world

You’ll be responsible for maintaining our FRS (Fraud Risk Suite) web SDKs. Next to that you’ll be driving the new (detection) capabilities of our SDK. This includes detecting and investigating fraud patterns & trends. You’ll be working closely with Threat Analysts and Product teams to enhance fraud detection. Part of your job is exploring and experimenting with (new and upcoming) browser APIs, and research how these APIs can be used to create new and novel detections mechanism. This requires a creative and out-of-the-box mindset. Proven experience with browser and JavaScript security research is a plus.

You should have the ability to research, develop, manage, test, and deploy browser-based JavaScript code in the following areas:

• Latest browser fingerprinting tactics
• Ability to research the underlying working of browser APIs
• Ability tocome up withnovel to use these APIs for detection; this includes looking for anomalies, side channels, and other side effects of these APIs
• Creating a production ready web SDK

Your daily work is to collaborate with the behaviour and device risk analytics tech team including backend engineers, data scientists and product managers.

You are expected to be able to work with minimal guidance as lead research and JavaScript engineer.

Since you will be working in a startup environment, passion and motivation are key to success and pleasure at work.

Responsibilities
Your key responsibilities will include:

• Maintaining our FRS web SDKs
• Driving the new (detection) capabilities of our SDK
• Detecting and investigating fraud patterns & trends
• Working closely with Threat Analysts and Product teams to enhance fraud detection
• Exploring and experimenting with (new and upcoming) browser APIs
• Researching how these APIs can be used to create new and novel detections mechanism

What We Offer

• A 12-month employment contract with the intention to extend. Subject to mutual satisfaction, this may lead to a permanent position.
• A competitive salary that reflects your skills and experience with a salary range between:80.000,- to 100.000,- annually.
• 25 Holidays per year
• 8% holiday allowance (included in annual salary).
• A Pension Scheme.
• A stimulating and supportive work environment that encourages growth and development.
• The opportunity to make a meaningful impactina rapidly growing tech company.
• Flexible Remote / Hybrid work from home options to promote work-life balance.
• Flexible working hours.
• ActiveThreatFabric events and FitFabric bootcamps.
• Active knowledge sharing huddles.

Who are we looking for? Skills and qualifications

• 8+ years relevant experience in JavaScript and or framework development.
• Familiar with Browser APIs including APIs needed for browser, mouse, keystroke, scroll dynamics.
• Able to work with Open Source development workflow using git.
• Excellent debugging and problem-solving skills.
• Knowledge of Docker is a nice to-have.
• Proficient English writing skills to document work and communicate project status.
• Be a team player and feel comfortable communicating and collaborating with other team members.

Creativity and Innovation:

• Generates and implements creative, innovative solutions to complex problems.

Problem-Solving:

• Communicates solutions clearly and concisely.
• Possesses a scale-up mentality where flexibility and adaptability are key.

Communication and Interpersonal Skills:

• Communicates technical concepts effectively to diverse audiences.
• Thrives in collaborative environments, fostering teamwork and cooperation.
• Demonstrates empathy and understanding in interpersonal interactions.

Continuous Improvement:

• Actively seeks opportunities to enhance workplace practices and product quality.
• Embraces a mindset of ongoing learning and development to stay ahead of industry trends.

Information Security, Business Continuity & Privacy:

• Proactively engages in maintaining information security and privacy standards.

Why us? Protecting people, not just systems
At ThreatFabric, your work has a direct impact on the lives of millions of people. Every day, fraudsters, scammers, and cybercriminals target individuals and financial institutions around the world. The technology we build helps stop these attacks before they cause harm, protecting not only money, but also trust, confidence, and peace of mind.

Unlike many technology companies, the problems we solve are real, complex, and constantly evolving. You'll work on challenges that make a measurable difference and see your contributions translated into solutions used by some of the world's leading financial institutions.

Work alongside experts who love what they do
ThreatFabric brings together security researchers, engineers, data scientists, threat intelligence specialists, and fraud experts from around the globe. We're passionate about our craft and continuously challenge each other to think differently, improve our solutions, and stay ahead of emerging threats.
Learning is part of our DNA. Whether through knowledge-sharing sessions, technical discussions, mentoring, or simply collaborating with highly experienced colleagues, you'll be surrounded by people who are eager to learn and equally eager to share their expertise.

Why people stay
People join ThreatFabric because they're excited by the technology and the mission. They stay because of the people. We celebrate successes together, learn from challenges together, and create an environment where talented individuals can do the best work of their careers while enjoying the journey along the way. Get in touch! Interested?
Looking for your next challenge? We'd love to hear your story. Apply through the Personio link below and we'll be in touch shortly. Whether you're ready to make a move or simply want to explore the opportunity further, we're happy to answer your questions and help you determine if ThreatFabric is the right fit for you. We aim to fill this position in Q3 2026.

What's next?
So, you've hit send - what happens now? First, we'll do a screening to ensure we're a good match. If all goes well, you'll be invited for an initial chat with us. Then, there's a second interview, and we may include an assessment to better understand your skills. Ready to take the plunge?

Please note: Pre-employment screening is part of our selection process. We do not accept unsolicited resumes from recruiters or employment agencies.