CREST-certified testing for mobile backends, partner integrations, automation APIs and application endpoints used by UK SMEs.
APIs often sit behind mobile apps, customer portals, CRMs, automation tools and partner integrations. They can expose powerful functions even when there is no visible web page for a user to click.
SME Cyber Solutions tests APIs for UK SMEs that need to understand whether endpoints protect data, enforce authorisation and behave safely under realistic misuse.
Authentication and tokens. We review token handling, expiry, refresh flows, session boundaries and whether unauthorised requests are rejected consistently.
Authorisation checks. We test whether users can access, create, update or delete objects that should belong to another user, tenant or role.
Endpoint behaviour. We assess methods, parameters, rate limits, errors, excessive data return and unsafe assumptions in integration logic.
Broken object-level authorisation. Attackers may be able to change an ID and access another customer record or transaction.
Excessive data exposure. Endpoints may return more information than the client needs, including hidden fields or sensitive metadata.
Weak rate limiting. Sensitive actions such as login, password reset or lookup functions may be vulnerable to automation or enumeration.
API testing is useful for SMEs with mobile apps, customer portals, partner integrations, CRM connections, automation platforms, bespoke software or any system where third parties or front ends call backend endpoints.
A typical scope includes the API base URLs, documentation or collections where available, authentication method, user roles, test accounts, sample requests and any rate limit or availability constraints.
You receive a clear report with an executive summary, technical findings, evidence, affected assets, risk ratings and recommended remediation. We prioritise the issues that could cause real business harm and explain them in a way that owners, technical teams and external stakeholders can act on.
After remediation, we can re-test agreed findings and provide updated documentation confirming whether the vulnerabilities have been resolved.
What is API penetration testing?
It is a controlled assessment of application programming interfaces, focused on whether endpoints enforce authentication, authorisation, validation and safe data handling.
Do you need API documentation?
Documentation, OpenAPI files or Postman collections help testing move faster, but we can also work from observed application traffic where documentation is limited.
Can API testing be combined with web application testing?
Yes. Many applications need both because the web front end and API endpoints expose different attack paths.
APIs often sit behind customer portals or SaaS platforms. If users interact with the API through a web front end, pair this with web application penetration testing.
This service is part of our wider penetration testing for UK SMEs. If you are unsure what to test first, book a scoping call and we will help define a practical, fixed-scope engagement.
Tell us what systems you rely on and we will recommend a practical penetration testing scope.