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BestPentestingby BugFoe
Offensive Security

API Penetration Testing

Your APIs carry your most valuable data. We test them the way attackers do — directly, systematically and with a focus on authorization.

Attack path focus LIVE

  • Full OWASP API Security Top 10 coverage
  • Two accounts per role for BOLA testing
  • GraphQL-specific test cases
  • Postman/OpenAPI-driven coverage

Overview

Modern products are API-first: your web app, mobile apps and partner integrations all talk to the same backend. Attackers know this — once they understand your API, they skip the user interface entirely and call endpoints directly.

The most damaging API flaws are authorization failures: changing an ID to read another customer's invoice, calling an admin-only function as a normal user, or setting a hidden field like role or price through mass assignment. Scanners can't judge who should see what. Our testers can.

We work from your OpenAPI/Swagger specification, Postman collections or GraphQL schema, plus traffic captured from your clients, to make sure every endpoint and method is covered — including old versions you may have forgotten are still live.

What's included

Object-level authorizationAccessing or modifying other users' objects by manipulating identifiers (BOLA).
Authentication & tokensJWT validation, token lifetime, refresh flows, API keys and credential stuffing protection.
Property-level authorizationExcessive data exposure and mass assignment of protected fields.
Function-level authorizationPrivileged endpoints reachable by lower-privileged roles.
Business flows & limitsAbuse of sign-up, purchase, coupon and OTP flows; resource consumption limits.
Inventory & configurationLegacy versions, debug endpoints, CORS, verbose errors and SSRF.

Our approach

  1. Specification reviewWe ingest your API definitions and map endpoints, methods, roles and data objects.
  2. Traffic analysisWe capture real client traffic to discover undocumented endpoints and parameters.
  3. Authorization matrix testingEvery sensitive endpoint is tested across roles and, for SaaS, across tenants.
  4. Input & logic testingInjection, deserialization, rate-limit bypass and business-flow abuse.
  5. Reporting & retestRequest/response evidence, root-cause fixes and verification after remediation.

What you receive

  • Endpoint coverage list
  • Findings mapped to OWASP API Security Top 10 (2023)
  • Reproducible requests (cURL/Postman) per finding
  • Authorization design recommendations
  • Retest report and attestation letter

Standards & frameworks

  • OWASP API Security Top 10
  • OWASP WSTG
  • OWASP ASVS
  • CWE
  • SOC 2
  • PCI DSS

Frequently asked questions

Do you need API documentation?

It is strongly recommended. Specifications and Postman collections let us spend paid time testing instead of discovering endpoints.

Can you test GraphQL APIs?

Yes — including introspection exposure, field-level authorization, query depth and complexity limits, and batching or aliasing abuse.

Do you test internal or partner APIs?

Yes, if they are in scope. Internal APIs often assume callers are trusted, which makes them valuable targets after an initial compromise.

Engagement timeline

What working with us looks like

Typical timeline for API Penetration Testing — we confirm exact dates in your proposal.

01Day 0ScopeCall, scope and fixed-price proposal
02Week 1Kick-offAccess, accounts and rules of engagement
03Week 1–2TestingManual testing with real-time critical alerts
04Week 2–3ReportExecutive + technical report and debrief
05+30 daysRetestFix verification and attestation letter
Sample report

Reports engineers can fix from and auditors accept

  • Executive summary in business language
  • Risk-rated findings with reproduction steps
  • Developer-ready remediation guidance
  • Retest results and attestation letter
Request a sample report

Ready to find your risks before attackers do?

Tell us what you need tested or monitored. A senior consultant replies within one business day with a scoped, fixed-price proposal.

  • Fixed-price proposal
  • Reply within 1 business day
  • NDA on request