24 hours
To a fixed-price scope
From $4,000*
Web app and API pentest
Free retest
Included in every engagement
2,000+
Clients served worldwide
*Final pricing is determined after scoping.
Why your APIs need a penetration test
What is API penetration testing? API penetration testing is a manual security test of the endpoints, authentication and authorization behind your web, mobile and partner integrations. It focuses on broken object level and function level authorization, mass assignment, rate limits and data exposure, aligned to the OWASP API Security Top 10.
APIs hold your customers' data, and authorization logic is often scattered across individual controllers. Scanners cannot see broken authorization, because every request they send looks valid.
Authorization is the main risk
Object-level and function-level flaws let users reach data and actions they should not.
Scanners send valid requests
Only testing with multiple roles and tenants shows broken authorization.
Buyers ask for API evidence
Enterprise security teams want a recent independent API test and proof of fixes.
OWASP API Security risk
What it means
What we test
API1 Broken Object Level Authorization
Users can reach other users' objects by changing an ID
Every endpoint, role and tenant pair
API2 Broken Authentication
Weak login, reset or token handling
Login, reset, token and session flows
API3 Broken Object Property Level Authorization
Users can read or write fields they should not
Excessive data in responses and mass assignment
API4 Unrestricted Resource Consumption
No limits on requests or resources
Rate limits and abuse resistance
API5 Broken Function Level Authorization
Lower roles can call admin functions
The full role matrix on every route
API7 Server Side Request Forgery
The API fetches attacker-chosen URLs
Fetch, import and webhook features
What enterprise security reviewers expect from an API pentest
- Coverage of every endpoint in scope. Not a sample.
- Testing across roles and tenants. With real account types.
- A documented methodology. OWASP API Security Top 10 and OWASP WSTG.
- Risk-rated findings. With reproduction evidence.
- Proof of remediation. Fixes verified by a retest.
- A shareable report. A summary buyers can attach to their vendor file.
Requirements vary by buyer. Confirm yours before scoping, and we will align the test to them.
API pentest services
We scope to the APIs that hold customer data, so the test supports your sales and audits and your budget is not spent outside them.
Authorization testing
Object-level and function-level checks across every endpoint, role and tenant pair.
Authentication and tokens
Login, password reset, OAuth 2.0 token flows and API key management.
Business logic
Workflow, limit and ownership checks that attackers abuse.
Input handling
Mass assignment, injection and SSRF in fetch and import features.
Rate limiting and abuse
Brute force, credential stuffing and enumeration resistance.
Data exposure
Excessive data in responses, verbose errors and permissive CORS policies.
Building in a specific sector? See SaaS penetration testing, fintech penetration testing and healthcare penetration testing. Need the cloud layer too? See cloud penetration testing.
How much does API penetration testing cost? A pentest of one web application and one API starts from $4,000* at Redfox, typically in 5 business days. Cloud testing starts from $2,400* and external network testing from $1,600*. *Final pricing is determined after scoping and depends on endpoints, roles, tenants and environments. You get a fixed quote within 24 hours.
API pentest methodology
Manual testing by senior consultants, aligned to OWASP WSTG, OWASP API Security Top 10, PTES and NIST SP 800-115. Not automated scanning.
01 / Scope in 24 hours
We import your API spec, provision test accounts and agree rules of engagement. You receive a fixed-price quote.
02 / Mapping
We build an endpoint inventory and a role and tenant matrix, and review authentication flows.
03 / Authorization testing
We run object-level and function-level checks across every endpoint, role and tenant pair.
04 / Logic and input testing, then reporting
We test mass assignment, rate limits, injection and data exposure. Critical findings are reported to you immediately, followed by a report and a walkthrough with the engineers who tested.
05 / Free retest
After you fix findings, we retest and issue a clean report and retest letter.
What an API pentest typically finds
These are the issues we most often find in APIs, and the ones that matter most to enterprise buyers.
Broken object level authorization
Export and download endpoints that return another tenant's data when given a project ID.
Broken function level authorization
A read-only role that can create admin API keys because the server never checks the role.
Mass assignment
Profile endpoints that bind every field and let a member promote themselves to admin.
No rate limiting
Login and password reset open to credential stuffing and account enumeration.
Excessive data exposure
User list responses and verbose errors that return more than the client needs.
Long-lived tokens
Access tokens that stay valid too long, plus permissive CORS policies.
How to prepare for an API penetration test
When should we schedule it? Book the test at least 6 weeks before a customer deadline or audit. A five-day test plus a three-week fix window needs about six weeks of runway.
01 / Share your API spec
An OpenAPI or Postman file covering the endpoints in scope.
02 / Provision tenants and roles
At least two tenants, with every role in each.
03 / Describe authentication
OAuth 2.0 flows, API key handling and any partner access.
04 / Use a staging environment
Mirroring production where possible, with a contact for critical findings.
05 / Reserve time to fix and retest
Plan engineering time so the free retest lands before the deadline.
The API pentest report
Reports designed to support your customer and audit evidence. We test security. Your customers and auditors decide what satisfies their requirements. Reports are delivered as PDF, ready to upload as evidence to your compliance platform.
Document
What it contains
Who uses it
Customer-safe summary
Scope, test dates, results and remediation status, without sensitive technical detail
Customers, procurement, sales
Full technical report
Risk ratings, proof-of-concept evidence, reproduction steps and fix guidance for every finding
Engineering and auditors
Methodology and appendices
Scope, approach and evidence, with strict QA on every report
Security reviewers
Retest report
Verified fixes and a retest letter
Customers and auditors
Case study: API authorization testing before an enterprise security review
Illustrative scenario. This example shows the kind of result this engagement delivers. It is not a named client.
The situation
A US workflow automation company (Series B, 180 employees) needed a third-party pentest and a clean remediation record to close a Fortune 500 deal within 30 days.
What we tested
A REST API with 140 endpoints, three roles with two tenant accounts each, an admin web console, OAuth 2.0 flows and API key management. 5 days of testing.
What we found
2 critical, 4 high and 6 medium findings. One customer could read another customer's data through the export endpoint, and a Viewer could create admin API keys.
The result
The company fixed all critical and high findings in three weeks. The retest confirmed the fixes, and a clean retest letter reached the buyer before the review deadline.
Download the full case study (PDF)
See the scope, approach, findings and retest results. Enter your details to get the PDF.
Why companies choose Redfox for API testing
Black Hat USA 2026 trainers
Official training provider for Advanced Adversary Tactics and Evasion at Mandalay Bay, Las Vegas. The tradecraft we teach is what we use on your systems.
16+ years in offensive security
Manual, exploit-driven testing, not scanner output.
5,000+ engagements
Delivered for 2,000+ clients worldwide, including SaaS, fintech and healthcare technology companies.
Free retest in every engagement
We verify your fixes and issue a clean report you can share with customers, partners and auditors.
Their focus on practical remediation helps security teams better understand and address potential exposure.
XEEFT.IO
Last updated October 2026.
API penetration testing FAQ
How much does API penetration testing cost?
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How long does a API penetration test take?
Will a penetration test affect our production systems?
What happens if you find a critical vulnerability?
What is API penetration testing?
Why can't a scanner find API authorization flaws?
Which standard do you use?
How often should we test our APIs?
Can you test mobile and partner APIs?
Do you test internal APIs?
Does API testing help with SOC 2 and enterprise reviews?
Can we share the report with customers?
Get your API pentest quote
A senior consultant replies within one business day with a fixed-price quote. Not sure what is in scope? Ask for a free 30-minute scope review.
Redfox Cyber Security Inc.
8 The Green, Ste. A,
Dover, Delaware 19901,
United States.
