Services

API Security Testing

APIs expose your data and business logic directly. We test whether yours enforce authorization on every request, return only what they should, and stand up to abuse.

Request a Security Assessment What we test

Why APIs need their own testing

Modern products are built on APIs: the mobile app, the single-page front end, partner integrations, and customer automation all talk to the same endpoints. Because an API accepts requests from anyone who can reach it, every endpoint has to check — on every call — who is asking and whether they are allowed to see or change the object they've requested.

When that check is missing or inconsistent, the impact is usually severe: one customer reading or modifying another's data simply by changing an identifier. These flaws are easy to introduce, hard to see in a user interface, and invisible to most scanners. API security testing focuses on finding them.

What we test

Coverage is agreed per engagement and guided by your API documentation, specifications, or observed traffic. Typical areas include:

Authentication
How clients obtain and present credentials or tokens, token validation and expiry, and weaknesses in key or token handling.
Object-level authorization
Whether changing an identifier in a request lets a caller read or modify objects that belong to someone else — the most common serious API flaw.
Function-level authorization
Whether ordinary users can call administrative or privileged endpoints, or use HTTP methods they shouldn't have access to.
Excessive data exposure
Responses that return more fields than the client needs — internal identifiers, other users' details, or sensitive attributes hidden only by the front end.
Input validation and mass assignment
Injection, unexpected types and values, and requests that set fields the caller should not control, such as roles or account status.
Rate limiting and abuse
Where agreed, whether endpoints can be abused for enumeration, brute force, resource exhaustion, or automated misuse of business functions.
Business logic
Sequencing, state, and workflow flaws — for example, completing steps out of order or replaying requests to gain an advantage.
Configuration and error handling
Verbose errors, debug endpoints, permissive CORS, outdated versions left reachable, and undocumented endpoints.

Not every area applies to every engagement. The areas tested are listed in the scope we agree with you before work starts.

How we test APIs

We start from whatever describes your API — an OpenAPI or similar specification, a Postman collection, documentation, or traffic captured from your application — and build a map of endpoints, objects, and roles. Testing then concentrates on the relationships between them: which identities can reach which objects through which operations.

Each finding is backed by the exact requests and responses needed to reproduce it, so your developers can verify the issue and the fix without guesswork.

Multiple identities

Authorization testing needs at least two accounts per relevant role (and per tenant, for multi-tenant products) so cross-account access can be checked.

Real examples, no customer data

Findings are demonstrated with test accounts and test data. We avoid accessing real customer records beyond what is needed to confirm an issue, and agree how to handle any we encounter.

What you receive

A written report designed for the developers who will fix the issues:

A summary of the API's overall security posture and the most significant risks.
Endpoint-level findings with risk ratings, affected operations, and request/response evidence.
Reproduction steps your team can run themselves to confirm each issue and its fix.
Remediation guidance, including where a fix belongs (for example, a shared authorization layer rather than individual endpoints).
Retesting of fixed issues where it is part of the agreed engagement.

Before testing starts

API documentation or a specification, and the base URLs for the in-scope environment.
Test credentials for each relevant role, ideally two accounts per role and tenant, shared through an agreed secure channel.
Agreement on rate-limit and abuse testing, so it doesn't affect real users.
Written authorization to test the API and the infrastructure it runs on.

Please don't send credentials, keys, or vulnerability details through the website form. We agree a secure channel once an engagement is confirmed.

Engagement process

From first conversation to verified fixes

A simple, predictable process. Actual timing and deliverables depend on the scope we agree.

Swipe to see all 6 steps

Step 01
Initial discussion
You tell us what you want assessed and why. We ask the questions needed to understand the application, API, or codebase.
Step 02
Scope & authorization
We agree targets, test types, environments, timing, and exclusions — and obtain written authorization before any testing.
Step 03
Assessment or review
Testing or code review is carried out within the agreed scope, with a named point of contact on both sides.
Step 04
Findings & reporting
You receive a written report with risk-rated findings, supporting evidence, and reproduction steps.
Step 05
Remediation guidance
We walk through the findings with your team and clarify how to fix each issue in your environment.
Step 06
Retesting, if agreed
Where included in the engagement, we verify that fixes are effective and update the report.

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