Senior Security Engineer – Mobile & Application Security (Fintech)

Location: UK; fully remote is acceptable, with hybrid work much preferred

Company

Leading financial technology company developing and operating mobile and backend platforms.

What you will do

• Improve mobile application security across iOS and Android.
• Assess and strengthen authentication, authorization, secure data storage, runtime protections, and hardening techniques.
• Secure APIs using OAuth, token-based authentication, abuse prevention, rate limiting, and business logic controls.
• Conduct threat modelling, design reviews, and hands-on security reviews of mobile and backend systems.
• Work with product managers and mobile and backend engineers to embed security controls throughout the development lifecycle.

Requirements

• Proven experience as an Application Security Engineer, Product Security Engineer, or Mobile Engineer focused on application security.
• Strong hands-on experience across mobile and API 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.
• Ability to work from the UK; fully remote work is acceptable, while hybrid work is preferred.

Nice to have

• Experience with React Native internals.

Culture & Benefits

• 12-month contract with the possibility of extension.
• Permanent employment may also be considered if preferred.
• Contract structured as outside IR35.