Senior Software Engineer - Behavioral Security Products

Abnormal AI; United Kingdom; On-site; GBP 70,000 - 90,000; Full time

Job summary

A cutting-edge cybersecurity firm in London is seeking a Senior Software Engineer to lead complex projects focused on developing scalable backend systems and ML tools. The ideal candidate will possess at least 7 years of experience, particularly in Python and cloud services like AWS. Responsibilities include managing feature deliveries that enhance system reliability and mentoring team members. A collaborative attitude and an affinity for modern developer tools are essential. This full-time position offers a unique opportunity in a dynamic environment.

Qualifications

• 7+ years of industry experience as a Senior Software Engineer.
• Proven expertise in backend systems and cloud environments.
• Strong understanding of scalable system design and monitoring.

Responsibilities

• Design and build scalable backend systems, APIs, and ML tools.
• Own end-to-end delivery of complex features impacting customers.
• Ensure reliability and operational excellence of critical systems.

Skills

Backend proficiency in Python

System design expertise

Knowledge of relational databases

Familiarity with gRPC and Kafka

Experience with AWS cloud services

Proficiency in Docker and Kubernetes

Strong collaborative skills

Job description

At Abnormal AI, we protect our customers against nefarious adversaries who are constantly evolving their techniques and tactics to outwit and undermine traditional approaches to security.

Abnormal is recognized as a top cybersecurity startup (Leader in the 2025 Gartner Magic Quadrant for Email Security Platforms), securing a Series D funding of $250 million at a $5.1 billion valuation in August 2024.

About The Team

The team is responsible for the ownership, development, and operation of the infrastructure and ML models, customer-facing APIs and internal tools that drive Abnormal's Account Takeover (ATO) protection product. This product is crucial for detecting malicious activity and safeguarding customers from account theft.

About The Role

We are looking for a Senior Software Engineer to take ownership of complex feature delivery and technical design for our ATO platform. This pivotal role involves evolving the platform to scale with expanding product requirements. The position requires a blend of hands‑on backend systems development, production ownership, stakeholder management, and team mentorship. The core goal is to enhance system reliability, reduce latency, and significantly accelerate feature release cycles.

What You’ll Do

Technical Delivery & Excellence

• Design, build, and iterate on scalable backend and ML systems, APIs, frameworks, and internal tools
• Own end-to-end delivery of complex features that directly impact customer experience.
• Ensure stability, reliability, and operational excellence of critical systems.
• Write clean, testable, and resilient code with attention to edge cases and performance.
• Write and review technical design documents and influence adoption across the team.
• Participate in code and design reviews, and contribute to on‑call rotations.

Leadership & Collaboration

• Collaborate with product managers, designers, and engineers to align on specifications and priorities.
• Break down complex projects into clear executable steps and drive them to completion.
• Actively contribute to roadmap discussions and propose long‑term technical plans.
• Communicate effectively in an async‑first environment, providing clarity on updates, challenges, and solutions.
• Mentor peers, share knowledge, and influence engineering practices across the team.

What We’re Looking For

• Ownership & Growth: A senior engineer mindset—able to independently lead complex projects and grow into a technical leader within the team.
• Attention to Detail: Deep focus on code quality, reliability, monitoring, and performance.
• System Thinker: Ability to anticipate long‑term scaling needs and design resilient architectures.
• Strong Collaborator: Comfortable influencing cross‑team goals, mentoring peers, and working in a distributed environment.
• GenAI Affinity: Proactive in leveraging modern developer productivity tools, including GenAI assistants, to accelerate delivery.

Must‑Have Skills

• 7+ years of industry experience, with proven expertise as a Senior Software Engineer.
• Strong backend proficiency in Python, with experience designing and scaling production systems.
• Proven experience with large‑scale system design, building resilient, scalable, and fault‑tolerant applications.
• Strong knowledge of relational databases and modern data storage technologies.
• Familiarity with service‑to‑service communication (gRPC, Kafka) and caching (Redis).
• Experience with AWS cloud services (S3, RDS) and deployment practices. Familiarity with containerization and orchestration (Docker, Kubernetes, Helm).
• Strong understanding of service health, monitoring, and incident response practices.
• Experience writing technical design documents and influencing adoption across teams.

Abnormal AI is an equal opportunity employer. Qualified applicants will receive consideration for employment without regard to race, color, religion, sex, national origin, disability, protected veteran status or other characteristics protected by law. For our EEO policy statement please click here. If you would like more information on your EEO rights under the law, please click here.

Senioriy level

Mid‑Senior level

Employment type

Full‑time

Job function

Engineering and Information Technology

Industries

Computer and Network Security

London, England, United Kingdom