Websites11 min read

Web App Security Audit & Pentest Cost for Mid-Market in Amsterdam (2026)

Mohamed Bah·Fondateur, Kolonell
September 4, 2026
Share:
Web App Security Audit & Pentest Cost for Mid-Market in Amsterdam (2026)

Web App Security Audit & Pentest Cost for Mid-Market in Amsterdam (2026)

Websites

The verdict in three sentences

An application pentest for a mid-market firm in Amsterdam costs between 6,000 and 20,000 EUR in 2026 depending on the surface tested, with report, remediation plan and re-test included. The baseline reference remains the OWASP Top 10 (injection, authentication, access control, data exposure). Budget 2 to 3 weeks: a modest investment against the cost of an incident (outage, data exfiltration, regulatory fine).

Pentest pricing grid in 2026

Price depends on scope, depth (black, grey, white box) and the number of roles to test.

Audit typeTypical scope2026 order of magnitude (EUR)Timeline
Standard app pentest1 web app, 2-3 roles6,000 - 12,0002 weeks
Deep pentestApp + API + back office12,000 - 20,0003 weeks
Code audit (review)Source code security review8,000 - 18,0002-3 weeks
Architecture auditCloud, network, segmentation7,000 - 15,0002 weeks
External intrusion testInternet-facing perimeter5,000 - 12,0001-2 weeks
Post-fix re-testVerify remediationsoften included2-4 days

A mid-market firm shipping a new application usually picks the deep app pentest (app + API), since the back office is often where access-control flaws hide.

What the OWASP Top 10 covers

The report ranks vulnerabilities by severity with an action plan. Here are the most commonly found categories and their impact.

OWASP categoryConcrete examplePotential impact
Broken access controlAccess to another account's dataCustomer data leak
Injection (SQL, etc.)Unfiltered queryDatabase theft/tampering
Cryptographic failuresSensitive data in clear textGDPR exposure
Security misconfigurationMissing header, exposed serviceTakeover
Weak authenticationNo attempt limitCompromised accounts
Vulnerable componentsOutdated libraryKnown exploit

Each vulnerability is rated (critical / high / medium / low) with an actionable recommendation, so you can prioritize fixes.

Need a professional website?

Kolonell builds websites that attract clients, optimized for the Sénégalese market. Free quote in 2 minutes.

Prefer a call back?

Leave your WhatsApp number and a Kolonell expert will get back to you within 1 business day. Free, no strings attached.

Mini case study

Nadia, CISO of a 400-employee industrial mid-market firm in Amsterdam. Before shipping a client portal handling 15,000 accounts, she orders a deep pentest (chosen budget: 15,000 EUR). The audit reveals 2 critical flaws (access control and injection) and 5 medium ones. Fix, then re-test included. By contrast, exfiltration of the 15,000 accounts would trigger a regulator notification, incident-response costs and a potential fine: in crisis management and lost trust alone, the order of magnitude exceeds 150,000 - 300,000 EUR. The audit cost / risk avoided ratio is around 1 to 10 or 1 to 20.

FAQ

Black, grey or white box: how does price differ? In white box (with code and account access), the tester goes faster and deeper, so better value. Black box simulates an external attacker but covers less surface at equal budget.

Is the re-test really included? With a serious provider, yes: after your fixes, a verification confirms the flaws are closed. Require it in the quote; it is what truly validates the fix.

How often should we redo a pentest? At least once a year and systematically before every major release or architecture change. Budget 6,000 to 20,000 EUR per campaign depending on scope.

Does an audit guarantee zero flaws? No: it strongly reduces risk by finding known, exploitable vulnerabilities at test time. Security is a continuous process, not a permanent certificate.

Should we warn the host before testing? Yes, written authorization and a test window are essential, especially on cloud infrastructure, to avoid automatic blocking during the engagement.

Let's scope your project. Share the scope to test (app, API, back office), the number of roles and your go-live date. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.

Tags:#security audit#pentest#OWASP#mid-market#Amsterdam#cybersecurity
Share:

Mohamed Bah

Fondateur, Kolonell

Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.