Services/Offensive Security

Offensive Application & Cloud Detection & Response Managed Detection & Response Incident Response & DFIR Security Program & Risk AI

CapabilityREST · GraphQL · OWASP API Top 10

API Penetration Testing

APIs carry your most sensitive traffic and are invisible to most testing. We test them the way attackers do.

Book a scoping call Offensive Security

§ 01Overview

The most common API flaw, broken object-level authorization, never shows in the UI: change an identifier and you read someone else's data. We test your APIs against the OWASP API Security Top 10 for authorization, data exposure, and abuse, by hand.

§ 02What we test

The surface we cover

Object-level authorization

Whether changing an identifier in a request returns data the user should not see.

Function-level authorization

Whether a user can call privileged actions they have no right to.

Excessive data exposure

Whether the API returns more data than the client needs or should receive.

Authentication and tokens

Key, token, and session handling, including expiry and scope.

Rate limiting and abuse

Whether the API is protected against automated and high-volume abuse.

§ 03How we approach it

A clear methodology, every time.

Scope and discovery

We inventory the endpoints, including forgotten ones, and agree the scope in writing.

Test by hand

We test authorization on every object and function, plus data exposure and abuse, against the OWASP API Top 10.

Prove impact

Confirmed findings are demonstrated safely with reproducible steps.

Report and retest

A report with fixes ranked by risk, plus a retest of the remediation.

§ 04What you get

Results you can act on.

Every engagement ends with documented findings and evidence, written for the technical team and for the board.

01Endpoint inventory and tested surface

02Reproducible findings with proof-of-concept

03Remediation guidance ranked by risk

04Remediation retest within 90 days

Go deeper

Read the in-depth guide to api penetration testing

→

Independent and vendor-neutral. We don't resell the tools we test.

Our only product is expertise and evidence, so our advice has no agenda but yours.

Independent

Vendor-neutral. No licences to sell, no conflicts of interest.

Senior-led

Every engagement is run by senior engineers, not handed to a queue.

Evidence-led

Reproducible findings and documented proof, not severity labels.

Regulator-ready

Built to satisfy NIS2, DORA, ISO 27001, and GDPR by design.

FAQ

Questions, answered

Why test APIs separately from the web app?

APIs are built for machines and often expose more than the UI. The most common flaws, broken object and function level authorization, are invisible in the interface and need dedicated, hands-on testing.

Do you test GraphQL and REST?

Yes, both, along with the authentication and authorization models behind them.

Do you retest the fixes?

Yes, a retest within 90 days is included.