API Penetration Testing Providers
API penetration testing focuses on the security of application programming interfaces, which form the backbone of modern web and mobile applications. Testers systematically evaluate REST APIs, GraphQL endpoints, SOAP services, and WebSocket connections for vulnerabilities including broken authentication, excessive data exposure, injection attacks, improper rate limiting, mass assignment, and broken object-level authorisation (BOLA).
Testing follows the OWASP API Security Top 10 and examines how APIs handle authentication tokens, enforce authorisation between users, validate input data, and protect against abuse.
API pen testing is increasingly important as organisations adopt microservices architectures, expose APIs to partners and third parties, and build API-first products. Insecure APIs are a leading cause of data breaches, making thorough security testing essential. API pen testing helps organisations that must comply with PCI DSS, HIPAA, SOC 2, and GDPR by identifying vulnerabilities that could lead to unauthorised data access or manipulation through API endpoints.
SECFORCE
Leading UK offensive security consultancy based in Canary Wharf, delivering CREST-accredited penetration testing and adversary simulation to organisations with the most demanding security requirements.
NCC Group
Global cybersecurity consultancy with CREST, CHECK, and CBEST accreditation, renowned for deep technical research and comprehensive penetration testing services.
Nettitude
CREST, CHECK, and CBEST accredited UK consultancy within Lloyd's Register, delivering premium penetration testing for government and critical infrastructure.
NetSPI
Leading penetration testing firm with the Resolve platform for continuous attack surface management, trusted by nine of the top ten US banks.
Pen Test Partners
The UK's largest independent security testing firm, renowned for IoT/OT research, CBEST red teaming, and CHECK/CREST-accredited penetration testing across all sectors.
PwC Cyber Security
Global Big Four professional services firm delivering CREST, CHECK, and CBEST-accredited penetration testing and red teaming services from London, serving the UK's largest enterprises and regulated organisations.
Dionach
Global enterprise cybersecurity consultancy founded in 1999 in Oxford, holding rare CREST STAR-FS accreditation and delivering penetration testing, red and purple teaming, and PCI QSA services across five international offices.
Trustwave
Global managed security provider with the elite SpiderLabs penetration testing team and deep PCI DSS compliance expertise.
Cyberis
CREST and CHECK-accredited UK penetration testing consultancy with CBEST approval, specialising in infrastructure, application, and simulated attack assessments across the public and private sectors.
Aristi
CHECK and CREST-accredited Birmingham-based cyber security consultancy with over 15 years of experience delivering penetration testing, red teaming, and OT security assessments for government and private sector clients.
Bridewell
Fast-growing CREST and CHECK-accredited UK cybersecurity consultancy with deep expertise in critical national infrastructure sectors.
Pentest People
CREST and CHECK-accredited UK penetration testing firm with an innovative SecurePortal platform and transparent pricing for mid-market organizations.
API Penetration Testing FAQs
What types of APIs can be tested?+
REST, GraphQL, SOAP, gRPC, WebSocket, and any custom API protocols can be tested. Testers need API documentation or access to the application that consumes the API.
Do you need API documentation for testing?+
API documentation (Swagger/OpenAPI specs, Postman collections) helps testers work more efficiently but is not strictly required. Testers can discover and map API endpoints through application analysis.
How is API pen testing different from web app pen testing?+
API pen testing focuses specifically on the API layer - authentication, authorisation, data validation, and business logic at the API level. Web app testing covers the full application including the user interface.