The Best Web Application Penetration Testing Companies in the UK (2026)

The best web application penetration testing companies in the UK for 2026 are listed below. Each one holds a CREST penetration testing accreditation and publishes a dedicated web application testing page, and each is compared on published pricing, retests and report turnaround so you can shortlist quickly.

1. Sencode

Sencode is a UK penetration testing company with a web application penetration testing page that includes business logic testing and follows the OWASP testing guide. That page states a complimentary retest with a stated retest window, fixed-scope pricing after a short scoping call, and a report turnaround after testing is complete. 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 web application penetration testing service covering manual exploitation of the OWASP Top 10, business-logic flaws, broken authentication, IDOR, SSRF and multi-tenant security boundaries, measured against OWASP ASVS. It is one of two companies on this list that publish pricing. Web application tests start from £5,000 on the pricing page, and the typical engagement costs £8,000 to £18,000 over 6 to 12 days. Small, at £5,000 to £8,000, is a single-role application over 5 days. Standard, at £8,000 to £18,000, is multi-role SaaS with payments over 8 to 12 days. Enterprise, at £18,000 to £35,000, is multi-tenant over 15 to 20 days. Verified: CREST Marketplace listing for EJN Labs.

Every engagement is a fixed price for a defined scope, and the quote arrives within 24 hours of a 30-minute scoping call. The published day rate for its CREST-certified consultants is £1,100 to £1,400, scaled by the rarity of the engagement, but clients are never billed by the day. The pricing page works through a standard SaaS example: 8 days of manual testing, 1 day of reporting and a typical price of £12,000.

Retesting of fixed findings is free until every finding is closed, with no time limit. By EJN Labs’ own figures, free retests save clients up to 35% against paying for retesting separately, and free rescheduling means a slipped release date costs nothing. There are no callout, cancellation or out-of-hours fees.

Findings are posted to a client portal as they are confirmed. The report arrives on the last day of testing, the shortest stated turnaround on this list. Each finding carries a CVSS score and remediation guidance, and every engagement ends with a signed letter of attestation. Testing is by UK-based, CREST-certified penetration testers. It is safe-by-default on production, with no denial of service, and out of hours slots are available. The business holds ISO 27001, ISO 9001, Cyber Essentials and Cyber Essentials Plus.

Sencode’s dedicated web application page, stated complimentary retest and stated report turnaround 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, with free retests until every finding is closed, a fixed quote in 24 hours and a report on the last day of testing, which is why it sits second.

3. JUMPSEC

JUMPSEC is a UK offensive security company whose application penetration testing page includes web application testing for access control, authentication, business logic and cross-site scripting, working to OWASP ASVS and the OWASP Web and API Top 10. CREST-accredited for penetration testing, vulnerability assessment, incident response, security operations centre and threat led penetration testing. Verified: CREST Marketplace listing.

4. OnSecurity

OnSecurity is a UK penetration testing company with a dedicated web application penetration testing page that covers issues such as SQL injection, cross-site scripting, CSRF, business logic flaws and permission weaknesses. That page states free retests for resolved issues within a flexible window. CREST-accredited for penetration testing. Verified: CREST Marketplace listing.

5. Sentrium

Sentrium is an independent UK penetration testing consultancy with a website penetration testing page covering websites and web applications, following the OWASP web security testing guide. Its penetration testing page states retesting of high and critical findings for a limited period after the test. CREST-accredited for penetration testing and cyber audit. Verified: CREST Marketplace listing.

6. Precursor Security

Precursor Security is a UK offensive security consultancy with a dedicated web application penetration testing page covering OWASP Top 10, business logic flaws, broken access control and authentication weaknesses, and describing its testing as fixed-price and OWASP ASVS-aligned. That page states a starting price for a small application and a free retest. Its penetration testing page states a report turnaround after 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 with a web app penetration testing page stating that tests follow the OWASP Testing Guide and include the OWASP Top 10 as standard, covering authentication, session handling, access controls and business logic. The page states a free retest for remediated vulnerabilities, and its penetration testing page states a report turnaround after completing the test. CREST-accredited for penetration testing, application security testing, vulnerability assessment, incident response and security operations centre. 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 a live, dedicated public page for web application penetration testing. We then recorded what each company publishes about pricing, retests and report turnaround. All pages were checked on 24 October 2026. Entries from three onwards are in no particular order.

• 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.
• A dedicated web application page. A home page that lists web application testing in a menu was not enough. Each entry needed its own public page for this service. Well-known testing companies without one 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 web application team usually has to prove that findings were fixed, and often by a customer or audit deadline. Where a company states its retest terms or report turnaround we noted it; where we could not find it, we recorded not found rather than inventing an answer.

How the companies compare

All seven companies hold verified CREST penetration testing accreditation, show a United Kingdom headquarters on their listing, and have a dedicated web application 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 taken from each company’s own public pages, linked in its profile above, as they stood on 24 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 you have to have a web application penetration test?

No rule names a web application penetration test as mandatory for every organisation. The duties that lead teams to commission one are narrower or broader than that. If your application sits in a payment card environment, PCI DSS 4.0.1 requirement 11.4.1 requires a documented penetration testing methodology based on an industry-accepted approach, and requirements 11.4.2 and 11.4.3 require internal and external penetration testing at least once every 12 months and after significant change. That applies to systems in the cardholder data environment, not to every web application.

UK GDPR Article 32(1)(d) requires a process for regularly testing, assessing and evaluating the effectiveness of your security measures. It does not name penetration testing as the method, but a test of the application that holds personal data is one recognised way to evidence that process. ISO 27001 does not require a penetration test either: Annex A 8.8 on management of technical vulnerabilities is apply-or-justify, and the ISO 27002 guidance for it lists periodic, documented penetration tests as one approach. The NCSC’s penetration testing guidance describes a penetration test as a method of gaining assurance in your vulnerability assessment and management processes.

For EU financial entities, DORA (Regulation (EU) 2022/2554) Articles 24 to 26 set digital operational resilience testing duties, and Article 26 requires threat-led penetration testing at least every three years for entities their authority identifies. The European Banking Authority keeps the DORA technical standards on threat led penetration tests with the other operational resilience material. In practice the request for a web application test usually comes from outside the team: an enterprise customer’s security questionnaire, a procurement panel, an auditor or a cyber insurer. For scope and cost, see our guide to penetration testing pricing.

What a buyer should ask a web application 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. Is the testing manual, and does it cover business logic and authorisation? Ask how testers check role boundaries, IDOR and multi-tenant separation, because a scanner alone does not find them.
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, and do we see findings before it? If a release or a customer deadline is driving the test, the gap between the end of testing and the report matters, as does live access to findings.
5. Can you test our production application safely? Ask how disruptive checks are handled, whether denial of service is excluded, and whether out of hours testing is available.
6. What is the fixed price for our scope? Ask for a day count and a day rate, not a range, and ask what a change of scope costs.

Get a quote

Read the published day rate of £1,100 to £1,400 and the web application starting price of £5,000 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 web application penetration testing from EJN Labs.