API security testing
APIs carry your data. Test them like they matter.
REST and GraphQL APIs tested for broken authorisation, data exposure and abuse, against the OWASP API Security Top 10.
Why teams call us
Problems this solves
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01
One ID change exposes another customer
Broken object-level authorisation lets a user read or change records by changing an identifier.
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02
APIs return more than the app shows
Mobile and web apps often hide fields that the API still sends to anyone who asks.
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03
Partners and integrations multiply access
Third-party keys and webhooks widen who can call what.
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04
No limits on expensive operations
Missing rate limits allow scraping, brute force and cost-driven abuse.
Our approach
Modern applications are mostly APIs, and attackers call them directly. We test each endpoint for who can call it, what it returns and how it behaves under abuse, using the OWASP API Security Top 10 (2023) as the baseline.
Testing covers authentication and token handling, object- and function-level authorisation, mass assignment, input validation, rate limiting, and the security of webhooks and partner integrations.
What is included
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Authorisation testing
Object-level and function-level authorisation checked across users and roles.
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Token and key handling
JWTs, OAuth flows, API keys and their expiry and scope.
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Data exposure
Responses reviewed for fields and records that should not be returned.
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Rate limiting and abuse
Brute force, enumeration and resource-consumption checks.
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Webhooks and integrations
Signature verification, replay protection and partner access.
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GraphQL specifics
Introspection, query depth and batching abuse.
What you receive
- Endpoint inventory and coverage matrix
- Findings with request and response evidence
- Risk rating and impact per finding
- Fix guidance per framework
- Retest and closure report
Technology we work with
- OWASP API Security Top 10
- OpenAPI
- GraphQL
- OAuth 2.0
- JWT
- Postman
- Burp Suite
Industries
How an engagement runs
Every engagement starts with a signed agreement and an advance payment as set out in your proposal. Work begins once both are complete.
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01
Scope
API documentation, environments, test credentials per role and exclusions agreed.
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02
Map
Endpoints, parameters and data flows documented.
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03
Test
Authorisation, authentication, input and abuse testing.
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04
Report and retest
Findings delivered with evidence; fixes retested.
Ready to start? Talk to us directly.
Tell us what you need in a few lines. A specialist replies with next steps and a written proposal before any work begins.
Frequently asked questions
Can't find your answer? Ask us
Do you need API documentation?
Can you test partner or open-banking APIs?
Do you test GraphQL?
Start with a conversation.
Share a few details. A specialist replies with next steps, usually starting with a short call.