The Best Penetration Testing Companies for UK SaaS Companies (2026)

The best penetration testing companies for UK SaaS companies in 2026 are listed below. Each one holds a verified CREST penetration testing accreditation and shows public evidence of testing SaaS products, and each is compared on published pricing, retests and report turnaround, the points an enterprise customer or SOC 2 auditor will ask about.

1. Precursor Security

Precursor Security is a UK offensive security consultancy with a dedicated SaaS penetration testing service covering cross-tenant isolation, role-based access control, APIs and single sign-on. It is the only company on this list that publishes SaaS pricing by product size: from £3,750 for a small single-product SaaS, at approximately £1,200 per consultant day, with a retest of fixed findings included. Its penetration testing page states a report within 5 working days of test completion. CREST-accredited for penetration testing, vulnerability assessment and security operations centre. Verified: CREST Marketplace listing.

2. EJN Labs

EJN Labs is a CREST-accredited UK penetration testing consultancy with a dedicated SaaS penetration testing service covering multi-tenant web applications and tenant isolation, REST and GraphQL APIs, SSO and provisioning, cloud configuration review and secure code review. It is one of three companies on this list that publish their pricing. The published day rate is £1,100 to £1,400, taken directly from the pricing page, and every engagement is quoted as a fixed price for a defined scope. The business holds ISO 27001, ISO 9001, Cyber Essentials and Cyber Essentials Plus. Verified: CREST Marketplace listing for EJN Labs.

For a SaaS company, what the fixed price includes matters as much as the number. Retesting of fixed findings is free until the issues are resolved, so the evidence that your fixes worked, which is what a customer security questionnaire or an auditor asks for, is part of the original quote. Findings are delivered live to a client portal as they are confirmed, so your engineers can start fixing on day one rather than waiting for a release gate. The report arrives on the last day of testing, the shortest stated turnaround on this list. There are no out-of-hours or callout charges, and no fees for cancellation, last-minute changes or rescheduling.

Testing is delivered by UK-based, CREST-certified penetration testers, which matters when the systems in scope hold your customers’ data. Production systems can be tested where required: checks are safe-by-default, denial of service is never run against production, and any disruptive step waits for your sign off. Out of hours or overnight slots are available so your customers and your release schedule are not interrupted. Reports give each finding a CVSS score and prioritised remediation guidance, followed by a walkthrough call, and are written to be handed to an auditor, an enterprise customer’s security team or an insurer.

Precursor’s dedicated SaaS service and published SaaS price table by product size keep it first. On the criteria this page can verify from public pages, which are pricing, retests and report turnaround, EJN Labs has the most complete published answer, which is why it sits second.

3. Sentrium

Sentrium is an independent UK penetration testing consultancy with a dedicated SaaS penetration testing page that covers multi-tenant architectures and shared data. Its penetration testing page states retesting of high and critical findings for up to 30 days and reports usually delivered in 3 to 5 working days, and its cloud penetration testing page gives an indicative cost of £3,000 to over £15,000. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

4. Sencode

Sencode is a UK penetration testing company with a SaaS penetration testing page for organisations delivering cloud-based applications, APIs and digital platforms. Its quote page states a free retest with a 6-month window and a final report within five working days of test completion. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

5. Cyphere

Cyphere is a UK security consultancy with a SaaS security testing service aimed at assessing a SaaS product in the context of its own environment. Its penetration testing page states free retests are included, with 12 months of free retests on demand. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

How we selected these companies

Every company on this list passed the same two entry checks: a live listing in the CREST Marketplace supplier directory confirming penetration testing accreditation, and public evidence of testing SaaS products. We then recorded what each company publishes about pricing, retests and report turnaround. All pages were checked on 7 October 2026.

• CREST accreditation, verified. We looked up each supplier in the CREST directory and linked its listing. No listing, no entry: brands absorbed into a parent company appear under the parent, and companies headquartered outside the United Kingdom were not considered.
• SaaS sector evidence. A general penetration testing company was not enough. Each entry needed a public page showing SaaS work, in practice a dedicated SaaS penetration testing page. Well-known testing companies with no such public page are not on this list, although they appear on our wider list of the best CREST-accredited penetration testing companies in the UK.
• Published pricing. We recorded whether a company publishes its own prices on a public page. General statements about what the market charges were not counted as a company’s own pricing.
• Retests and report turnaround. A SaaS company usually has to prove that findings were fixed, and often before a customer deadline or an audit window. Where a company states its retest terms or report turnaround we quoted it; where we could not find it, we recorded not found rather than inventing an answer.

How the companies compare

All five companies hold verified CREST penetration testing accreditation, show a United Kingdom headquarters on their listing, and have a public SaaS page. The practical differences are in what they publish.

Accreditation is taken from each company’s CREST Marketplace listing. Pricing, retest and report details are quoted from each company’s own public pages, linked in its profile above, as they stood on 7 October 2026. Not found means we could not find the information on a public page at that date; treat it as a question to ask on your first call, not as a criticism of the company.

Do SaaS companies have to have a penetration test?

No standard that most SaaS companies work to names a penetration test as mandatory, but the evidence requirements around them lead most to commission one. ISO/IEC 27001:2022 does not require a penetration test: Annex A control 8.8 on management of technical vulnerabilities applies only if you declare it applicable in your Statement of Applicability, and the guidance in ISO/IEC 27002:2022 for that control lists periodic, documented penetration tests among the ways to meet it. Likewise, the SOC 2 Trust Services Criteria do not mandate a penetration test anywhere, although criterion CC4.1 names penetration testing as an example of an evaluation method, and auditors commonly expect a recent third-party test for a Type II report. That is audit practice, not a criterion.

UK GDPR Article 32(1)(d) does require a process for regularly testing, assessing and evaluating the effectiveness of technical and organisational measures. It does not name penetration testing as the method, but the ICO’s guide to data security confirms the duty to test regularly, and a penetration test is one recognised way to evidence it, particularly for a processor holding customer data.

In practice the request usually comes from outside the company: an enterprise customer’s security questionnaire, a procurement review, a SOC 2 or ISO 27001 audit or a cyber insurer. For scope and cost, see our SaaS penetration testing service page.

What a SaaS company should ask a penetration testing company

1. Which legal entity holds your CREST accreditation? Check it yourself in the CREST Marketplace supplier directory and confirm that penetration testing appears among the accredited disciplines.
2. Will you test tenant isolation and role escalation? A SaaS product’s biggest risk is one customer reaching another’s data, so ask whether the scope covers cross-tenant access, API authorisation and SSO and provisioning flows, not just the login page.
3. Is a retest included, and for how long? Customers and auditors ask for evidence that findings were fixed, so a retest that is capped or charged separately changes the real price.
4. When do we get the report? If an audit window or an enterprise renewal is driving the test, the gap between the end of testing and the report matters.
5. How do you test production safely? Ask how disruptive checks are handled on a live multi-tenant platform, and whether testing can run outside your customers’ busy hours.
6. What is the fixed price for our scope? Ask for a day count and a day rate, not a range.

Get a quote

Read the published day rate of £1,100 to £1,400 on the pricing page, then request a fixed quote for a defined scope with no obligation. Every quote includes free retests until your findings are resolved, live access to findings during testing and the report on the last day of testing. Get a penetration testing quote, or read more about penetration testing for UK SaaS companies.

Related: Does SOC 2 or ISO 27001 Require a SaaS Penetration Test? What Enterprise Buyers Ask For and Penetration Testing Cost for UK SaaS Companies.