What is Application Security? — UK Software Development Guide

4 min readJune 2025ClickMasters Technical TeamReviewed by James Whitmore, CTO
what is application security

Direct Answer

Application security (AppSec) is the practice of designing, building, and testing software to protect against security threats and vulnerabilities. It encompasses: secure coding practices, security testing (SAST, DAST, penetration testing), threat modelling, access control, encryption, and security code reviews.

Application-security in the UK

Application security has specific UK regulatory significance. UK GDPR Article 32 requires "appropriate technical and organisational measures" — the ICO interprets this as including application-level security controls such as encryption, access controls, and regular security testing. Cyber Essentials covers five baseline technical controls. Cyber Essentials Plus requires external security verification including penetration testing. The NCSC (National Cyber Security Centre) publishes Secure by Design guidance. For regulated sectors: DTAC Domain 3 (HealthTech), FCA operational resilience requirements (FinTech), and GDS security standards (GovTech) all mandate application security practices.

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