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Cybersecurity & Compliance

API Security Testing

Testing REST, GraphQL, and internal APIs for authentication, authorization, injection, and abuse risks — the layer that powers your apps and integrations but is easy to expose by accident.

Talk through your API's exposureAll services
Overview

The layer your apps quietly depend on

APIs are the connective tissue of modern applications, and they carry a distinct set of risks: broken object-level authorization, excessive data exposure, missing rate limits, and authentication that is weaker than the UI it sits behind. We test REST, GraphQL, and internal service APIs against these classes of issue, informed by frameworks such as the OWASP API Security Top 10. Testing covers authentication and token handling, object- and function-level authorization (can user A reach user B's data?), input validation and injection, and abuse cases like enumeration and unthrottled requests. Because APIs are often consumed by machines rather than browsers, we pay particular attention to the assumptions developers make about who is calling and how. You receive reproducible findings with example requests, severity ratings, and remediation guidance your backend team can apply directly.

What’s included

  • REST, GraphQL, and internal API coverage
  • Aligned to the OWASP API Security Top 10
  • Object- and function-level authorization testing
  • Rate-limiting, enumeration, and abuse-case checks
  • Reproducible findings with example requests
Who it's for

Who exposes an API worth testing

  • Product teams whose mobile apps, single-page front ends, and partner integrations all depend on one shared backend API.
  • Platform and B2B companies who publish a public or partner API and carry responsibility for how customers' data is exposed.
  • Multi-tenant SaaS teams who need certainty that object-level authorisation holds across every endpoint, not just most of them.
  • Engineering teams moving to microservices or GraphQL who want internal service APIs tested rather than assumed to be trusted.
When you need it

When to test the API directly

  • You are about to publish a public or partner API and want authentication, rate limiting, and authorisation tested before external developers arrive.
  • Your API is multi-tenant and you need to verify that changing an identifier in a request cannot return another tenant's records.
  • You have adopted GraphQL and want introspection exposure, query depth, batching abuse, and field-level authorisation examined.
  • Internal service-to-service APIs were built assuming a trusted network, and you now want that assumption tested properly.
  • A customer or auditor has asked specifically for API penetration testing rather than a general web application test.
Deliverables

What your backend team receives

Every engagement ends with something your team can act on — not a slide deck.

  • A prioritised findings report with example requests and responses reproducing every issue
  • Authorisation matrix results showing which roles could reach which objects and functions during testing
  • Coverage mapping against the OWASP API Security Top 10 categories
  • Backend-focused remediation guidance your API developers can implement directly
  • An optional retest verifying that authorisation and validation fixes hold
How it works

How we work through your endpoints

The same predictable shape whether the work is an assessment or a build, so you always know what happens next.

  1. 1

    Discover

    We start by understanding your systems, goals, and constraints — scope, risk tolerance, and what success looks like — so the work is aimed at your actual problem, not a generic template.

  2. 2

    Assess or build

    For security work, we test and analyse against recognised standards. For development, we build in small, reviewable increments. Either way, you see progress early and can change direction.

  3. 3

    Report or ship

    You get clear, prioritised deliverables — a report your engineers can act on, or working software shipped to your environment — with the context to understand what was done and why.

  4. 4

    Support

    We stay available after delivery: retesting fixes, iterating on the product, and answering the questions that come up once real users and real traffic arrive.

FAQ

API Security — common questions

How is API security testing scoped and priced?

We scope by endpoint surface and role complexity, then give you a fixed quote before testing. The drivers are how many endpoints or GraphQL operations exist, how many roles and tenant types need to be tested against each other, whether REST and GraphQL are both in scope, and whether internal service APIs are included. Good API documentation or a collection speeds scoping and lowers effort noticeably.

Do you need documentation or credentials to test our API?

Credentials, yes — meaningful API testing requires them. Most serious API vulnerabilities live behind authentication, so we ask for at least two accounts per role type to test whether one user can reach another's data. Documentation such as an OpenAPI specification, GraphQL schema, or Postman collection is very helpful but not mandatory; without it we spend more time on discovery, which we account for in scoping.

Is API testing not already covered by a web application test?

Partly, but not sufficiently. A web application test exercises the API through the interface, so it only reaches endpoints and parameters the front end happens to use. Dedicated API penetration testing works directly against the service: undocumented endpoints, mass-assignment on fields the UI never sends, missing rate limits, and object-level authorisation on every route. If your API also serves mobile apps or partners, testing it directly matters more.

Do you test GraphQL differently from REST?

Yes. REST and GraphQL fail in different ways, so the technique differs. For REST we focus heavily on object- and function-level authorisation, parameter tampering, and endpoint enumeration. For GraphQL we add introspection exposure, query depth and complexity abuse, batching and aliasing attacks, and field- and resolver-level authorisation, since a single endpoint can hide very uneven access control. Both are assessed against the OWASP API Security Top 10.
Related services

Test these alongside your API

Teams that come to Safe Tech AI for api security frequently need these too.

  • Web Application Security Testing

    Deep testing of your web applications against OWASP-class risks — injection, broken access control, authentication flaws, and more — with findings mapped to how your app actually works, not a generic checklist.

    Learn more

  • Vulnerability Assessment & Penetration Testing (VAPT)

    Simulated attacks that find exploitable weaknesses before real attackers do. We combine broad automated scanning with hands-on manual testing, then hand you a prioritised, reproducible report your engineers can act on.

    Learn more

  • Mobile Application Security Testing

    Security review of iOS and Android apps — local data storage, the APIs they call, and platform-specific risks — so sensitive data on the device and in transit is properly protected.

    Learn more

Undocumented endpoints don't stay undocumented forever.

Have your REST or GraphQL API tested directly for broken authorisation, weak rate limits, and abuse cases, with example requests for every finding.

Talk through your API's exposure