The Best Penetration Testing Companies for UK Fintech (2026)

The best penetration testing companies for UK fintech in 2026 are listed below. Each one holds a verified CREST penetration testing accreditation and shows public evidence of working with fintech and payments firms, and each is compared on published pricing, retests and report turnaround.

1. OnSecurity

OnSecurity is a UK penetration testing company with a dedicated fintech penetration testing service covering payment processing security, mobile banking vulnerabilities and Open Banking API threats, and it publishes fintech articles on Open Banking API security testing and PCI DSS compliance testing. Its fintech page states that vulnerabilities are reported as they are discovered, and its homepage FAQ states that fixed findings are retested for free within a retesting window. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

2. EJN Labs

EJN Labs is a CREST-accredited UK penetration testing consultancy with a dedicated fintech penetration testing service covering payment and open banking APIs, merchant dashboards, wallets, card issuing, payment orchestration, KYC onboarding and iOS and Android banking apps. It is one of three companies on this list that publish 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 and Cyber Essentials Plus. Verified: CREST Marketplace listing for EJN Labs.

For a fintech, 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 partner banks, enterprise customers and PCI DSS assessors usually ask 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. The report arrives on the last day of testing. 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 account details, payment instructions or cardholder 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 payment flows and release schedules 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 a partner bank, a PCI DSS assessor or an auditor.

OnSecurity’s dedicated fintech service page and its fintech articles on Open Banking and PCI DSS 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. Sencode

Sencode is a UK penetration testing company whose fintech penetration testing page covers payment platforms, financial applications, APIs, mobile products and cloud environments. That page states complimentary retesting with a 6 month retest window, and its penetration testing page states that the report is typically furnished within 5 days after testing is complete. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

4. CodeShield

CodeShield is a UK cyber security company whose penetration testing for fintech page covers payment platforms, neobanks, lending apps, open banking providers, wealthtech and crypto firms. The same page states that it can retest once findings are addressed, without stating the terms. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

5. Sentrium

Sentrium is an independent UK penetration testing consultancy with a financial services and fintech page covering payments, loans and the sensitive financial data they depend on. Its penetration testing page states a free retesting window to validate fixes. Its service pages give indicative price ranges by test type. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

6. Precursor Security

Precursor Security is a UK offensive security consultancy with a financial services sector page that names payment processors and fintech companies among the organisations it works with. It also publishes pricing: its cost page states engagements from £2,500 at approximately £1,200 per consultant day, with a 30-day retest, and 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.

7. Evalian

Evalian is a UK data protection and security consultancy whose finance and fintech cyber security page describes its services for finance and fintech businesses, a useful pairing for firms that want testing and UK GDPR advice from one supplier. Its penetration testing page states a free retest and a report within seven days of completing the test. CREST-accredited for penetration testing, vulnerability assessment, incident response and security operations centre. Verified: CREST Marketplace listing.

8. Kroll (incorporating Redscan)

Kroll is a global risk advisory firm whose UK cyber practice absorbed Redscan. Redscan’s fintech cyber security page sets out the security challenges of fintech, from banking and payments to asset management and insurance. Kroll holds CREST accreditation for penetration testing, incident response and security operations centre. Redscan has no standalone listing, so check the Kroll entry. Verified: CREST Marketplace listing for Kroll LLC.

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 work with fintech and payments firms. 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.
• Fintech sector evidence. A general penetration testing company was not enough. Each entry needed a public page showing fintech or payments work: a dedicated fintech or financial services page that names fintech, payment platforms or payment processors. 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 fintech usually has to prove that findings were fixed, and often by a partner bank’s or customer’s deadline. 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 eight companies hold verified CREST penetration testing accreditation, show a United Kingdom headquarters on their listing except Kroll, and have public fintech or payments evidence. 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 fintech firms have to have a penetration test?

No FCA rule names a penetration test as mandatory for an authorised fintech. The duties that lead firms to commission one are broader. Regulation 98 of the Payment Services Regulations 2017 requires each payment service provider to establish a framework with appropriate mitigation measures and control mechanisms to manage the operational and security risks of its payment services, and to give the FCA an updated and comprehensive assessment of those risks and of the adequacy of its controls, annually or at shorter intervals the FCA directs.

The FCA’s operational resilience chapter, SYSC 15A, applies under SYSC 15A.1.1R to electronic money institutions, payment institutions and registered account information service providers for their payment and e-money activities. SYSC 15A.2.1R requires a firm to identify its important business services, and SYSC 15A.5.1R requires a testing plan showing how it will gain assurance that it can remain within its impact tolerances. That is scenario testing in general, and a penetration test can inform it by identifying exploitable weaknesses in the systems those services depend on. UK GDPR Article 32(1)(d) requires a process for regularly testing the effectiveness of your security measures. It does not name penetration testing as the method.

Where a fintech stores, processes or transmits cardholder data, PCI DSS v4.0.1 is different: requirement 11.4.2 calls for internal penetration testing and requirement 11.4.3 for external penetration testing, each at least once every 12 months and after significant change. PCI DSS is a card scheme standard that your acquirer or payment partner holds you to, not legislation. Outside the rules, the request usually comes from partner banks, enterprise customers and investors during due diligence. For scope and cost, see our guide to financial services penetration testing.

What a fintech 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 the payment and open banking APIs for business logic flaws, not just known vulnerabilities? Ask how authentication flows, payout changes and balance handling under concurrent requests are covered.
3. Where are the testers based, and who will see our data? Account details and payment instructions may be visible during testing, so ask where the people doing the work are located and how findings are stored.
4. Is a retest included, and for how long? Partner banks and PCI DSS assessors ask for evidence that findings were fixed, so a retest that is capped or charged separately changes the real price.
5. When do we get the report? If a partner bank deadline, an audit date or a release is driving the test, the gap between the end of testing and the report matters.
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 fintech.

Related: Winning Bank Contracts: Where Penetration Testing Sits in PRA SS2/21 Vendor Reviews and Penetration Testing Cost for UK Fintechs and Payment Firms.