The verdict in three sentences
A source code security audit before fundraising costs GBP 5,000 to 15,500 in the UK or USD 6,500 to 19,500 in the US in 2026 for 5 to 12 days of expert work, depending on codebase size and pentest scope. It should be ordered 3 to 6 weeks before investors' technical due diligence, leaving time to fix critical flaws rather than discovering them in the investor's report. An unfixed critical flaw rarely kills a deal, but it often leads to a warranty clause, an escrow or a valuation discount that a preventive audit avoids.
What investors check in technical due diligence
For a Series A, most funds hire a firm that spends 3 to 10 days on your product. They look less for perfection than for maturity signals: a team that knows its risks and handles them. The most frequent 2026 findings are always the same.
| Common finding | Frequency in early-stage SaaS | Severity for the investor | Indicative fix effort |
|---|---|---|---|
| Dependencies with critical CVEs | 60 to 70% | Medium | 1 to 3 days |
| Secrets (API keys, passwords) in the Git repo | 30 to 40% | High | 1 to 2 days + rotation |
| Broken access control between tenants | 15 to 25% | Critical | 3 to 10 days |
| No logging of admin access | 40 to 50% | Medium | 2 to 4 days |
| Backups never test-restored | 50% | High | 1 to 2 days |
| Personal data without documented legal basis (UK GDPR, CCPA) | 35% | High | 2 to 5 days |
| No MFA on cloud accounts | 25% | High | 0.5 day |
Cross-tenant data leakage is the finding that worries investors most, because it hits the core commercial promise of a B2B SaaS.
Audit scope and price in 2026
| Package | Content | Days | 2026 price (GBP / USD) | Total timeline |
|---|---|---|---|---|
| Express review | Dependency analysis, secret scanning, architecture review | 5 | 5,000-6,500 / 6,500-8,000 | 3 weeks |
| Standard audit | + manual code review of sensitive areas (auth, payments, multi-tenancy) | 8 | 8,000-10,500 / 10,000-13,000 | 4 weeks |
| Full audit | + targeted pentest to OWASP ASVS level 2, cloud infrastructure | 12 | 12,000-15,500 / 15,000-19,500 | 5 to 6 weeks |
| Re-test after fixes | Verification of critical fixes | 1 to 2 | 1,000-2,200 / 1,300-2,700 | 1 week |
| SOC 2 or ISO 27001 readiness option | Control gap analysis, roadmap | 3 to 5 | 3,500-6,000 / 4,300-7,500 | 2 weeks |
The expected deliverable includes a 2-page executive report readable by an investor, the list of vulnerabilities ranked by severity (CVSS), and a prioritized remediation plan with effort estimates in development days. That plan, shown in due diligence with fixes already applied, is what changes the perception of risk.
The timeline that works
Week 1: scoping, access to the repo and a staging environment. Weeks 2 and 3: analysis and pentest. Week 4: debrief and remediation plan. Weeks 4 to 6: your team fixes critical and high issues, then re-test. Starting the audit after signing the term sheet often leaves too little time: ideally, start while preparing the data room.
Mini case study
Emma, CEO of a 14-person HR SaaS startup in London, is raising a GBP 5 million Series A at a GBP 20 million pre-money valuation, with US investors in the round who ask about SOC 2. She orders a standard audit at GBP 9,500 and a re-test at GBP 1,600. The audit reveals broken access control letting a user read another customer's employee records by changing an ID, and storage keys in Git history. Fix: 7 development days, about GBP 4,000 of internal cost. Total cost: GBP 15,100. Without fixes, a fund could have required a 5% escrow of the proceeds for 12 months (GBP 250,000 locked) or a 1 to 2% valuation discount, GBP 200,000 to 400,000. The audit represents under 0.3% of the amount raised.
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FAQ
Must the auditor get access to the full source code?
Yes, a white-box audit is 2 to 3 times more effective than a black-box test for the same budget. Access is read-only under NDA and ends at the debrief.
Isn't a free automated scan enough?
Automated tools catch vulnerable dependencies and secrets well, about 40% of findings. Multi-tenant access control flaws, the most serious, need 3 to 5 days of manual review.
Should we show the audit report to investors?
The executive summary and the remediation plan with fix status, yes: it signals maturity. Technical vulnerability details stay confidential until fixed.
Does the audit replace SOC 2 or ISO 27001?
No. It prepares the ground: SOC 2 Type II typically costs USD 30,000 to 80,000 in 2026 including tooling and auditor fees over 6 to 12 months. For a Series A, a recent audit plus a compliance roadmap is usually enough.
How often should we repeat the audit?
Once a year, and before every raise or major enterprise contract. The annual re-audit usually costs 30 to 50% of the initial audit.
Let's scope your project. Send us your stack, codebase size and target due diligence date: we will price an audit between GBP 5,000 and 15,500 (USD 6,500 to 19,500) over 3 to 6 weeks. 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.
