GladiatorRX

API security testing

API security testing for the systems behind your apps

Your APIs carry your most valuable data, and they're where automated scanners struggle most. We test every endpoint, role and tenant boundary to confirm that each user can see and do only what they should.

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Sample findingGRX-0412
CriticalCVSS 9.1

Invoice API returns other companies' invoices

Area
Billing API
Category
OWASP API1 · Object-level authorisation
Impact
Any customer could read every other customer's invoices.
Fix

Validate tenant ownership on every request, and use non-sequential identifiers.

Retested and closed

Coverage

What we test

We agree the exact scope with you on the scoping call. These are the areas we typically cover.

API types

  • REST and JSON APIs
  • GraphQL
  • gRPC and WebSockets
  • Partner and third-party integrations

Access control

  • User-to-user and tenant-to-tenant isolation
  • Role and permission checks
  • Admin and internal endpoints

Authentication

  • OAuth 2.0 and OpenID Connect flows
  • Token handling and expiry
  • API keys and secrets
  • OTP and login protections

Business logic

  • Rate limiting and abuse prevention
  • Payment, refund and coupon flows
  • Data over-exposure in responses

Deliverables

What you receive

  • Findings mapped to the OWASP API Security Top 10
  • Per-endpoint coverage summary
  • Fix guidance your developers can apply directly
  • Free retest of fixed issues
  • Attestation letter

Aligned to OWASP API Security Top 10

Is it right for you?

Choose this if…

  • Your product is API-first or has a mobile app
  • You run multi-tenant SaaS
  • You expose APIs to partners or customers
  • You handle payments, health or financial data
Request a quote

Process

How the engagement runs

  1. Scope

    A 30-minute call to agree on targets, testing windows and rules of engagement. You get a fixed quote.

  2. Map

    We map what's in scope: features, user roles, integrations, and anything exposed that wasn't on the list.

  3. Test

    Hands-on testing by certified testers. Critical issues are reported to you straight away.

  4. Report

    A summary for leadership, plus a detailed finding for each issue with evidence and a specific fix.

  5. Retest

    We verify your fixes and issue an updated report and attestation letter.

FAQ

API security testing: common questions

What do you need from us?

API documentation (an OpenAPI file or Postman collection), plus test accounts for each user role. With two accounts per role we can test isolation properly.

Can you test GraphQL?

Yes. GraphQL needs its own approach to authorisation and query limits, and our methodology covers it.

Is API testing included in a web app pentest?

Partly. A web app test covers the APIs the website uses. A dedicated API test covers every endpoint, including ones only mobile apps or partners call.

Related

Often combined with

Penetration testing

Hands-on security testing of your web applications, networks and cloud by certified testers.

PTES · OWASP WSTG · NIST SP 800-115 Learn more

Vulnerability assessment

A broad, verified sweep of your infrastructure for known weaknesses and missing patches.

CVSS 3.1 / 4.0 · NIST SP 800-115 Learn more

Mobile security testing

Android and iOS app testing, including the backend APIs each app depends on.

OWASP MASVS · MASTG Learn more

Find out where you're exposed before an attacker does.

Tell us what you need tested. We'll reply within one business day with questions or a fixed quote.

Get a quote Call +91 96231 11662