Senior Application Security Engineer

Arcus Search; Greater London; Hybrid; GBP 90,000 - 130,000; Full time

Job summary

Arcus Search is seeking two Senior Security Engineers focused on mobile application security to raise the security bar across our mobile and backend platforms. This hands-on role collaborates with product managers and engineering teams to identify, design, and implement effective security controls throughout the development lifecycle.

Ideal candidates have proven experience in application security or mobile engineering, knowledge of mobile-to-API interactions, and hands-on ability to work

Qualifications

• Proven experience in Application Security, Product Security, or Mobile Engineering with a strong focus on app security
• Strong understanding of mobile-to-API interaction patterns and common attack vectors in modern mobile apps
• Ability to work hands-on and pragmatically with engineering teams

Responsibilities

• Hands-on role identifying, designing, and implementing security controls across mobile and backend platforms
• Conduct threat modeling and design reviews to strengthen security in the SDLC
• Perform hands-on security reviews of mobile apps and backend systems
• Collaborate with product managers and engineers to embed security into development processes

Skills

Mobile security

Application security

API security

Threat modeling

Secure SDLC

Cross-functional collaboration

Hands-on security reviews

React Native

Tools

Mobile/Backend security tools

React Native internals

Job description

Senior Security Engineer – Mobile & Application Security

We are looking to hire two Senior Security Engineers with a strong focus on mobile application security to help raise the security bar across our mobile and backend platforms. This is a hands‑on role, working closely with engineering and product teams to identify, design, and implement effective security controls throughout the development lifecycle.

Key Focus Areas

Mobile App Security (iOS & Android)

• Authentication and authorization mechanisms
• Secure data storage
• Runtime protections and hardening techniques

API Security

• OAuth and token-based authentication
• Abuse prevention and rate limiting
• Identification and mitigation of business logic vulnerabilities

Secure SDLC

• Threat modeling and design reviews
• Hands‑on security reviews of mobile and backend systems

Cross-functional Collaboration

• Partnering closely with product managers and mobile/backend engineers to embed security into day‑to‑day development

Ideal Background

• Proven experience as anApplication Security Engineer,Product Security Engineer, orMobile Engineerwith a strong focus on application security
• Strong understanding of mobile‑to‑API interaction patterns and common attack vectors in modern mobile applications
• Ability to work hands‑on and pragmatically with engineering teams

Nice to Have

• Experience withReact Native internals