The verdict in three sentences
A serious security audit for a B2B site costs EUR 2,500-9,000 depending on whether it is a passive audit or a full pentest based on the OWASP Top 10, delivered in 2 to 4 weeks. The real deliverable is not the report but the prioritised remediation plan (EUR 1,500-6,000 of fixes) and the retest that confirms the vulnerabilities are truly closed. Against the cost of an exploited flaw (data breach, GDPR fine, service outage), the audit is a high-leverage defensive investment.
Audit packages and their price
2026 order of magnitude for a B2B website security audit in Amsterdam:
| Package | Price | Timeline | Content |
|---|---|---|---|
| Passive audit / scan | EUR 2,500-4,000 | 1-2 wks | Automated scan, config, headers |
| Grey-box pentest | EUR 4,500-6,500 | 2-3 wks | OWASP Top 10, manual tests |
| In-depth pentest | EUR 7,000-9,000 | 3-4 wks | Black-box + API + retest |
| Remediations | EUR 1,500-6,000 | Per findings | Prioritised fixes |
| Validation retest | Often included | 1 wk | Fix verification |
An audit without a retest is incomplete: demand that the post-fix validation be included or quoted from the start.
Deliverables and OWASP scope
A professional audit covers at minimum the major OWASP Top 10 categories and produces actionable deliverables:
| Deliverable | Included | Purpose |
|---|---|---|
| Executive report | Yes | Summary for management |
| Detailed technical report | Yes | For developers |
| Severity classification | Yes | Prioritisation (critical/high/medium) |
| CSP header check | Yes | XSS/clickjacking protection |
| Injection / auth tests | Yes | OWASP A01/A03 |
| Proof of concept (PoC) | Yes | Concrete evidence of risks |
| Remediation plan | Yes | Costed roadmap |
| Retest after fixes | Per quote | Final validation |
CSP headers and server configuration are the fastest, most cost-effective fixes: often a few hours of work to close classic risks.
Mini case study
Mr Visser, CISO of a financial-services SME in Amsterdam, commissions a grey-box pentest at EUR 5,500 on his client portal handling sensitive data. The audit reveals 2 critical flaws (injection and weak authentication) and 5 medium ones.
Remediations costed at EUR 3,200, retest included. Total cost: EUR 8,700. In contrast, a real exploitation of the authentication flaw could have exposed the data of ~1,200 clients: between breach notification, potential fine and lost contracts, the risk estimate exceeds EUR 80,000. Defensive ROI: the audit and its fixes cost about 10 % of a single avoided major incident.
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FAQ
What budget should I plan for a B2B security audit in 2026?
Expect EUR 2,500-9,000 depending on depth: passive audit at the low end, in-depth pentest with API at the high end. Add EUR 1,500-6,000 for remediations.
How long does an audit take?
Between 2 and 4 weeks for a pentest, including testing, report writing and debrief. A simple passive scan can be done in 1-2 weeks.
Is the retest really necessary?
Yes: the retest confirms the fixes truly close the flaws. An audit without a retest leaves doubt about the effectiveness of the remediations. Demand it in the quote.
What is the OWASP Top 10?
It is the reference list of the 10 most critical web security risks (injection, authentication, XSS...). A serious audit systematically covers these categories.
How much does an actually exploited flaw cost?
Between mandatory notification, GDPR fine (up to a percentage of turnover), recovery and loss of trust, a major incident frequently exceeds EUR 50,000-100,000 for an SME. The audit is a prevention investment.
Let's scope your project. Tell us the site type, the data processed and the audit level you want: we will frame an OWASP audit with a prioritised report, remediations and retest. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
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.
