Authentication
Token issuance and validation, OAuth and OIDC flows, API key handling, JWT alg confusion, refresh-token replay.
Find the authorization gaps and tenant isolation flaws in your APIs before customers do.
API penetration testing for REST, GraphQL, and webhooks — broken authorization, tenant isolation, abuse resistance, and GraphQL-specific issues the OWASP API Top 10 documents.
What's at stake
Broken object-level authorization is the most common API breach pattern — and the hardest for a scanner to catch.
If customers or partners integrate with your APIs, a tenant isolation gap or IDOR is a direct path to another customer's data. The question is whether you find it first.
A standard web app pentest will not cover your GraphQL surface, walk every tenant boundary, or test webhook signature and replay controls. This engagement does.
What we cover
Six API attack surfaces we close, mapped to OWASP API Top 10.
Authorization (BOLA / BFLA)
Object-level (IDOR) and function-level access checks across roles, tenants, and partners.
Rate limiting and abuse
Brute-force resistance, business-logic abuse, account enumeration, mass-assignment, and credential-stuffing controls.
Data exposure
Excessive data return, debug fields, verbose errors, internal IDs leaking PII, response shape across roles.
GraphQL specifics
Introspection, batching, depth and complexity limits, alias DoS, persisted-query bypass, field-level auth.
Webhooks and integrations
Signature verification, replay protection, SSRF via outbound calls, callback-URL validation.
How we test
Endpoint by endpoint, role by role.
- 01
Surface mapping
Reconcile your spec (OpenAPI, GraphQL schema) with the endpoints actually exposed in production.
- 02
Per-role testing
Test each endpoint against every documented role and across tenant boundaries.
- 03
Logic and abuse
Mass-assignment, business-logic flaws, replay, race conditions, abuse-resistance.
- 04
Walkthrough and retest
Live finding walkthrough; retest of reported findings after your fixes ship — included in scope.
What you get
One report. Three audiences.
For the board
A one-page summary of what was tested, what was found, what was fixed.
For auditors and partners
Executive section with OWASP API mapping and SOC 2 / ISO / PCI / HIPAA cross-walks.
For engineers
Each finding has the exact request, response evidence, severity, and a paste-ready remediation.
Want to know what's exposed in your API?
A quick scoping call gives you a fixed scope, price, and start date.
Get a straight answer Typical scenarios
Three patterns we see most often.
Multi-tenant SaaS API
Validate tenant isolation across every endpoint and every role.
Public or partner API
Auth, rate limiting, abuse resistance, and partner-token isolation under scrutiny.
GraphQL endpoint
Introspection, batching, alias DoS, and field-level authorization tested explicitly.
Adjacent engagements
Most teams pair API testing with one of these.
Further reading
Background from our team.
FAQ
API testing — common questions
What is API penetration testing?
A hands-on assessment of your REST, GraphQL, and webhook surfaces — focused on OWASP API Security Top 10 issues, multi-tenant isolation, authorization, and abuse resistance.
Do you test GraphQL differently from REST?
Yes. GraphQL has its own attack surface: introspection, batching attacks, depth and complexity DoS, alias confusion, and field-level auth gaps. We test these explicitly alongside standard auth checks.
How do you handle authentication for testing?
We work from test accounts representing each role and tenant in scope. For partner or B2B APIs we coordinate credentials before testing begins.
How long does an API pentest take?
2–3 weeks of testing plus a week of reporting for a single API. Larger multi-tenant or multi-API surfaces run longer — scope and date confirmed on the call.
Will the report align with OWASP API Security Top 10?
Yes. Findings are mapped to the OWASP API Security Top 10 and to your compliance framework (SOC 2, ISO, PCI, HIPAA).
Want a credible answer when a customer, auditor, or your board asks how secure you are?
A quick scoping call with the senior tester who would run your engagement. No slides, no pitch — we look at what you have, tell you what we would test first, and give you a fixed scope, price, and date.