September 29, 2025
An independent buyer’s guide for UK security leaders comparing trusted pentest providers.
Mohammed Khalil
Choosing the right penetration testing partner is mission critical in 2025’s high stakes cyber landscape. Nearly 43% of UK businesses reported experiencing a cyber attack or breach in the past 12 months. High profile incidents underscore the risk a single ransomware breach at a UK retailer this year was estimated to cost around £300 million in lost profits. At the same time, attackers are leveraging AI to craft more sophisticated exploits and phishing e.g. deepfake AI impersonation tactics are emerging, raising the bar for security testing.
With threats growing and compliance pressures mounting, regulators now demand rigorous testing and proof of remediation, organizations can’t afford a trial and error approach to penetration testing. The UK market has matured, featuring both homegrown specialists and global consultancies with UK based teams. This independent, research driven ranking aims to help UK companies navigate the options and find a provider that fits their needs. We’ve taken an unbiased look at the leading penetration testing firms, from boutique experts to big four affiliates, evaluating them against transparent criteria detailed below.
The result is a list of the top penetration testing companies in the UK for 2025, each with proven expertise. Whether you run a small tech startup or a large regulated enterprise, this guide will help you compare vendors, understand their strengths and limitations, and ultimately make a confident buying decision in a procurement friendly manner. Editorial note: DeepStrike is included in this list based on the same evaluation criteria applied to all providers.
Our Evaluation Methodology: To ensure an unbiased top companies list, we developed a rigorous methodology focused on Experience, Expertise, Authority, and Trustworthiness E E A T. Each provider was scored across multiple factors:
UK Ranking Emphasis: In line with the above, UK centric qualities were prioritized. UK headquartered and operated firms naturally ranked highly. Global consultancies are included only if they have a deep UK penetration testing practice e.g. NCC Group’s large UK team. CREST accreditation was treated as a strong quality indicator especially for government/finance engagements but not an absolute filter. Ultimately, every company on this list met our bar for technical excellence and proven UK delivery. We believe this approach ensures the rankings remain fair, procurement friendly, and relevant to UK organizations’ needs.
Now, let’s dive into the top penetration testing providers operating in the UK, and see how they stack up. Each company listing includes key facts, headquarters, founding year, size, etc., an explanation of why they stand out, notable strengths, potential limitations, and ideal best for use cases. The list is organized with UK based specialists first, followed by global players with a strong UK presence, reflecting the local emphasis of our rankings.
Why They Stand Out: DeepStrike is a next generation provider that combines elite human expertise with a modern SaaS delivery model. Founded by recognized security experts including co authors of the Web Application Hacker’s Handbook, DeepStrike has a strong pedigree in manual penetration testing. Every engagement is heavily manual and creative, the firm’s philosophy is to simulate real attackers with custom exploits and multi-step attack chains, rather than relying on off the shelf scanners. What truly differentiates DeepStrike is its fully managed PTaaS platform: clients get a cloud dashboard to track findings in real time, integrate with Slack/Jira for updates, and manage remediation. This hybrid approach of expert testing + continuous platform gives clients the best of both worlds deep one off tests and ongoing monitoring.
Key Strengths:
Potential Limitations:Being a newer player founded 2016, DeepStrike is still growing its brand recognition and global footprint. They are in the process of obtaining CREST accreditation, but as of 2025 are not yet CREST certified, some highly regulated UK clients might require an already CREST member for compliance reasons. Additionally, while the company’s size allows for personal attention, very large enterprises requiring hundreds of tests per year or extensive on site presence might find DeepStrike’s boutique team relative to big firms stretched. However, for the vast majority of mid-sized and even large UK organizations, DeepStrike’s capabilities are more than sufficient and often more cost flexible than large audit firms.
Best For: Organizations that want a high impact penetration testing program with both depth and ongoing coverage. DeepStrike is ideal for tech driven companies including scale ups and cloud first enterprises that value creative, manual testing and continuous engagement. It’s the top choice if you seek a true security partner who can adapt to your development pace for example, DevOps teams releasing frequently, or any business that wants to integrate pentesting into a continuous security best practices cycle rather than a one and done yearly audit. Editorial note: DeepStrike is included as Best Overall based on the evaluation criteria above, with no preferential treatment.
Why They Stand Out: NCC Group is one of the world’s largest dedicated cybersecurity firms and a heavyweight in the UK pentesting scene. With a 20+ year history, NCC has built an unparalleled knowledge base and resource pool including dedicated research teams that spend thousands of hours annually on discovering new vulnerabilities and attack techniques.. Their penetration testing services cover virtually every niche from wireless and hardware testing to social engineering, which means they can handle very complex, large scope engagements. Crucially, NCC Group carries significant credibility in regulated sectors. They are a CREST member and one of the few with NCSC CHECK status to perform government work. Enterprises often choose NCC for high assurance needs because of its proven methodology and the comfort of working with an established, publicly listed company.
Key Strengths:
Potential Limitations:NCC Group’s enterprise focus comes with premium pricing and potentially longer lead times. They are often priced at the higher end of day rates in the UK reflecting their scale and overhead. Smaller organizations or startups might find NCC’s offerings less accessible or more than they need. Also, due to their size, clients may sometimes experience variability in engagement teams while NCC’s top talent is excellent, in some cases junior consultants might lead smaller engagements, so ensuring the right team mix is important. Finally, large firms like NCC may not offer the same level of flexibility or personal touch as a boutique, processes can be a bit formal or bureaucratic for fast moving clients.
Best For: Large enterprises, financial institutions, and government agencies that require maximum assurance and a broad range of services. NCC Group is best for organizations that have complex, global IT environments or strict compliance mandates and want a provider with an impeccable pedigree. If you need a one stop partner to handle everything from routine pentests to full red team exercises at scale and are willing to invest for quality, NCC Group is an excellent choice. It’s especially suited for regulated industries where having a CREST certified, well known vendor will instill confidence with stakeholders and auditors.
Why They Stand Out: Pen Test Partners often known as PTP has a reputation as a go to boutique for deep technical expertise. Unlike many firms that diversify, PTP focuses almost solely on penetration testing and related offensive work. This specialization means their consultants are truly experts, many are conference speakers, DEF CON presenters, or contributors to security research. PTP is particularly known for tackling unusual and challenging assignments: hacking maritime and aviation systems, testing connected cars, compromising IoT gadgets, etc. Their team famously has tested everything from ships and planes to cars and industrial control systems. As a result, PTP is one of the few firms of its size capable of high end engagements like CBEST Bank of England’s rigorous framework simulations. Despite being an independent 100 person company, they punch well above their weight in skill and have gained global recognition through their public research and thought leadership.
Key Strengths:
Potential Limitations:Pen Test Partners’ focus on complex, bespoke testing means they may be relatively expensive for simpler needs. They tend to engage on projects that require significant expertise, smaller businesses looking for a quick, basic pentest might find PTP’s offering more than necessary and their pricing aligned to their specialist skills. Additionally, their capacity is limited to about 100 consultants while that is large for a boutique, extremely large scale rollouts e.g. hundreds of apps simultaneously could be challenging. PTP also does not provide many ancillary services e.g. managed SOC, extensive GRC consulting they stick to what they do best. So, if you prefer a single vendor for all security services, PTP’s narrow focus might require you to use them alongside other providers.
Best For: Organizations that need top tier technical depth in penetration testing. PTP is best for mid size to large companies who value quality over quantity for instance, a bank needing a no compromise red team engagement, or a manufacturer seeking to secure unusual connected technology. It’s an excellent fit for critical infrastructure providers and any business facing sophisticated threats and possibly regulators that demand an experienced, independent testing partner. If you have a challenging environment or a novel technology to be tested, Pen Test Partners should be high on your shortlist.
Why They Stand Out: Nettitude is distinguished by its dual DNA strong technical pentesting capabilities combined with a compliance/audit mindset. Now operating under the LRQA banner Lloyd’s Register Quality Assurance, Nettitude bridges the gap between pure hackers and auditors. This makes them especially valuable for clients who not only want vulnerabilities found, but also need the process and results to satisfy regulators, auditors, or customer due diligence. Nettitude’s team conducts penetration tests with an eye toward standards like ISO 27001, PCI DSS, and Cyber Essentials, often bundling these services. For example, a Nettitude engagement might include a web app pentest and simultaneously provide evidence needed for an ISO 27001 control or a PCI requirement a one stop shop for security assessment and compliance reporting. They are CREST approved and CHECK certified, reinforcing their credibility in the UK market.
Key Strengths:
Potential Limitations:Nettitude’s compliance oriented approach might feel too process heavy for some tech companies purely seeking offensive excellence. They may not appear as cool or cutting edge as some boutique hacker firms, as their branding leans toward professionalism and assurance. If an organization’s main goal is creative red teaming above all else, other firms might be flashier in that regard. Additionally, being part of a larger corporate group LRQA could introduce some bureaucracy e.g., potentially slower sales or legal processes than a small firm. Pricing is generally aligned to enterprise consulting rates, while they do offer fixed scope packages for SMEs, their sweet spot is often mid to large clients with compliance budgets. Lastly, extremely agile development teams might find Nettitude less flexible in ad hoc testing compared to a smaller PTaaS focused provider, as their engagements tend to be well scoped and scheduled though this is often necessary for formal compliance tests.
Best For: Heavily regulated organizations and those that want a meticulous, standards aligned approach. Nettitude is a top choice for financial institutions, insurance companies, government agencies, and global firms in sectors like shipping or energy where both security and compliance are paramount. If your goal is to tick all the right boxes CREST, CHECK, PCI, ISO and get a solid penetration test, Nettitude offers that package. It’s ideal for security conscious companies that must regularly report cybersecurity status to regulators, audit committees, or board executives. Nettitude will ensure your penetration testing results are packaged in a business friendly, compliance friendly manner.
Why They Stand Out: Bulletproof positions itself as a one stop cyber partner for SMEs and mid market firms, combining penetration testing expertise with a range of security services tailored to smaller budgets. They are CREST certified and emphasize making security accessible for everyone which translates to pentest offerings that are packaged and priced for organizations that may not have in-house security teams. Bulletproof’s testing services cover the usual technical areas, but with an added focus on meeting common compliance needs PCI, GDPR, Cyber Essentials. For example, they often bundle penetration testing with Cyber Essentials Plus certification packages, or provide quick turnaround tests to help a company satisfy a partner due diligence requirement. Their ability to simplify the process and guide less experienced clients is a big plus. In short, Bulletproof shines at taking enterprise grade practices CREST accredited testing, etc. and delivering them in a streamlined, cost effective way for businesses that need security but don’t have unlimited resources.
Key Strengths:
Potential Limitations:Bulletproof’s breadth of services, pentesting, MDR, training, etc. can mean they are not as purely specialized in high end penetration testing as some competitors. For extremely complex or advanced testing scenarios e.g. nation state level threat simulations or niche industrial systems, a boutique specialist might outperform them. Their focus on SMEs also means they might not have as much experience with ultra large enterprise environments although they do serve some bigger clients, their sweet spot is mid market. Additionally, while their packaged approach is great for consistency, very custom needs might be less of a fit. For instance, if an organization wants an open ended, creative red team that goes beyond standardized test plans, they might lean towards a more specialized firm. In terms of certifications, Bulletproof is CREST accredited good but not known for things like CHECK or CBEST assignments so for certain government or financial sector needs, they might not check every box.
Best For: Small and mid size companies in the UK that need reliable penetration testing and security services without the complexity or cost of big consultancies. Bulletproof is ideal for businesses seeking to achieve compliance with PCI DSS, Cyber Essentials, ISO 27001 as part of their security testing the company will ensure you pass those hurdles. It’s also a strong choice for any mid market firm that values quick, efficient service and perhaps wants an ongoing security partner for multiple needs testing, managed SOC, etc.. Examples: a fintech startup preparing for a SOC 2 audit, a regional law firm needing a web app test for client assurance, or an online retailer looking to bolster security and get certified Bulletproof would serve these scenarios well.
Why They Stand Out: Secarma is renowned in the UK security community for its pure offensive security focus and attacker mindset. The company’s origins date back to a pentesting firm established in 2001, and over the years Secarma has maintained a culture of hardcore ethical hacking. They are the team you call when you want to be truly challenged by your pentest. Secarma’s consultants often operate like real threat actors, their red team engagements might include multi month persistent attacks, custom malware implants, and covert techniques to evade detection. In fact, Secarma has been an early contributor to frameworks like CBEST and GBEST UK’s bank and government red teaming programs. They also invest in R&D, having developed in house tools e.g., their EndView implant mentioned in industry circles. Unlike some firms that do pentesting alongside many services, Secarma sticks almost exclusively to offensive security, which has honed their skills in this domain.
Key Strengths:
Potential Limitations:As a specialized offensive shop, Secarma may not be the right fit for routine or compliance driven testing for a small web app, their skills and pricing are geared towards more complex scenarios. They are often engaged by organizations that already have a mature security program and want to push the limits. If you’re new to security testing, Secarma’s style might be overkill. Additionally, Secarma doesn’t advertise broader services, they are not the ones to do your ISO 27001 audit or manage your SOC. So, they work best alongside your internal team or other providers not as a one stop provider for all security needs. Their availability can also be an issue: truly good red teamers are in high demand, so you may need to schedule well in advance for a major engagement. Finally, because they focus on offense, you should ensure you have the capability to act on their findings. Secarma will give you the honest ugly truth about your weaknesses, but remediation will largely be up to you or other consultants.
Best For: Organizations that want to be challenged at the highest level of penetration testing. Secarma is best for medium to large enterprises that have gotten past basic security audits and now need to test their resilience against skilled, determined attackers. It’s a top choice for companies with mature security operations banks, government bodies, large healthcare, etc. looking to validate their defenses through realistic red teaming. If your priority is to simulate an advanced cyber attack to see how far an intruder could get and to train your defenders in the process Secarma is an ideal partner. It's an offense on hard mode, perfect for fortifying organizations that cannot afford a single serious breach.
Comparison of Top UK Penetration Testing Providers 2025
| Company | Specialization | Best For | Primary Region | Compliance Creds | Ideal Client Size |
|---|---|---|---|---|---|
| DeepStrike | Manual pentesting + continuous PTaaS | All around security assurance, Best Overall 2025 | UK London HQ, global delivery | Pursuing CREST, testers hold OSCP/CISSP, aligns with ISO 27001/PCI | Mid size tech firms to large enterprises needing flexible testing |
| NCC Group | Enterprise scale, full spectrum security services | Large regulated enterprises, gov’t | Global UK origin | CREST, CHECK, ISO 17025 lab, ISO 27001 | Large enterprises hundreds/thousands of assets |
| Pen Test Partners | Deep dive boutique pentesting, IoT/OT expertise | Critical infrastructure, elite testing needs | UK Buckingham HQ, US/EU offices | CREST, CHECK, CBEST/TIBER licensed, OSCP/OSWP staff | Mid to large orgs needing specialized expertise |
| Nettitude LRQA | Pentesting + compliance integration | Regulated industries, finance, etc. | UK Birmingham HQ, global via LRQA | CREST, CHECK, ISO 27001, PCI QSA team | Mid to large enterprises with heavy compliance needs |
| Bulletproof | Affordable pentest & 24/7 SOC for SMBs | SMBs and mid market needing compliance | UK London HQ | CREST accredited, Cyber Essentials, ISO 27001 | Small to mid size businesses incl. startups |
| Secarma | Adversary simulations & red teaming | Advanced threat emulation, red team drills | UK Manchester HQ | CREST, CHECK, OSCP/GIAC team | Mid to large orgs with mature security programs |
Table: A quick comparison of the top UK pentesting companies. Compliance Creds highlights notable certifications or accreditations each provider holds.
One important consideration when choosing a penetration testing partner is whether you’re better served by a large enterprise provider or a smaller boutique firm. Both have advantages, and the right choice depends on your organization’s size, culture, and needs. Here’s a breakdown to help guide that decision:
Selecting a penetration testing company can be daunting. Many providers market similar sounding services, so it’s crucial to look past the buzzwords and focus on what really matters. Here are some buyer’s tips to avoid common pitfalls and zero in on the right vendor:
In summary, match the provider to your organization’s complexity and culture. A 20 person startup probably doesn’t need a Big Four consultancy, likewise, a multinational may struggle with a 5 person shop for a huge project. Evaluate your needs: if you require hand holding, quick turnarounds, or specialized skills, lean toward a capable boutique. If you need scale, multi service bundles, and a well oiled machine, a larger firm is fitting. Remember, a credible provider big or small will welcome your questions about their approach and experience. Use those conversations to judge if they truly get your business and can meet your expectations.
Penetration testing costs can vary widely depending on scope and provider. In the UK, day rates typically range from around £600 up to £1,500+ per day per tester, based on the tester’s seniority and the firm’s overhead. A small basic test 2-3 days on one web app or external network might cost roughly £3k–£6k. A medium engagement 1 week on multiple systems could be in the £7k–£15k range. Large scale or red team exercises spanning several weeks can run £20k–£30k+. Enterprise class providers tend to charge towards the higher end but may include more comprehensive reporting and project management. Keep in mind, price also depends on factors like: is it black box vs. white box white box can be quicker with access, how many IPs/apps, and how deep the testing goes. Always request a detailed quote. Good vendors will break down the hours or days and the deliverables. Beware of quotes that are dramatically lower than others, as mentioned earlier, they might be cutting corners e.g., doing only automated scans. It’s better to prioritize value a thorough test that might cost a bit more is worth it when the average UK breach can cost vastly more to remediate.
Generally, yes the skills and certifications of the testing team are more important than any particular tool they use. Tools like Burp Suite, Nessus, Metasploit, etc. are widely available, what differentiates providers is how expertly they use tools and perform manual testing. Certifications like OSCP, OSWE, CREST, CISSP, etc., signal that a tester or firm has proven knowledge and adheres to industry standards. For example, a CREST certified company has had its methodologies assessed, which adds trust. That said, certifications shouldn’t be the only criteria, not every great hacker has a cert, and some cert holders might lack real world creativity. But as a buyer, if you don’t have other info, certs are a useful quality filter. On the other hand, fancy proprietary tools or AI platforms touted by a vendor should be taken with a grain of salt. Ask what problems those tools solve and how they integrate with human expertise. A firm that leads with its people’s expertise and mentions tools as supporting aids is often a better bet than one that markets a push button pentest tool. In summary: prioritize people and process over product. The best providers have skilled humans who know how to leverage tools and when to go beyond them.
The duration of a penetration test depends on scope and complexity. A straightforward test of a single web application or small network segment can often be done in 3-5 days of testing with reporting time on top of that. This might equate to one week elapsed. Broader assessments, like a full external and internal network pentest for a mid size company, might take 1 2 weeks of effort. A comprehensive red team simulation can run 4-6 weeks or more, since it involves phases of reconnaissance, exploitation, persistence, etc., often spaced out to mimic a real attacker. Keep in mind scheduling and reporting add to the timeline: after active testing, firms usually take a few days to compile the report. Also, high severity findings may be reported earlier in an engagement for safety. If you have a deadline e.g., a compliance audit, communicate that upfront many providers can adjust to meet a specific delivery date as long as they know. In terms of lead time, good providers can be booked out weeks in advance, so it’s wise to engage a provider at least a month or two before you need the test to start, if possible. Some smaller tests can be expedited, but complex ones benefit from planning.
A quality penetration test report typically includes:
Better reports will prioritize issues by risk and possibly provide a roadmap for remediation e.g., fix these critical items immediately, these medium items next, etc.. They should also include the testing methodology and scope clearly what was in scope, what was out, any assumptions. Watch out for overly brief reports e.g., a one page letter saying everything’s fine or a raw dump of scan results that indicate a poor assessment. Instead, expect a document that not only lists bugs but explains the implications of each and contextualizes them for your organization. Some firms also offer a live walkthrough or debrief meeting as part of deliverables. This is very valuable, as you can ask questions and understand the findings better. Don’t hesitate to ask a prospective provider for a sample redacted report to ensure their reporting meets your expectations.
At minimum, annually. Most standards PCI DSS, ISO 27001, etc. and insurance policies suggest at least an annual penetration test of critical systems. Many UK businesses do it twice a year for example, an external network test and an internal/application test at six month intervals. However, the trend is moving toward more frequent testing of changing assets. If you have a web application that updates monthly, waiting a whole year could be risky, in such cases, quarterly or per release testing is advisable. Some organizations adopt continuous penetration testing or PTaaS models where certain assets are tested on an ongoing cycle with automation plus periodic human testing. Also consider triggering tests after significant changes: new infrastructure deployment, major app version release, or after an incident to harden defenses. For cloud environments or CI/CD workflows, it’s increasingly common to integrate security testing continuously including automated scans plus manual tests of major changes. In summary, do a full scope test at least once a year, but assess your risk and update frequency to decide if key systems need more frequent attention. Many companies find that a mix of continuous scanning, an annual big pentest, and targeted tests in between on new features or high risk areas works well. Ultimately, penetration testing should be an ongoing practice, not a one time checkbox, the threat landscape changes too fast for a yearly snapshot to be sufficient in all cases.
Not strictly necessary, but highly recommended for certain scenarios. CREST is a respected accreditation body in the UK choosing a CREST certified provider gives you assurance that the company follows industry best practices and that their testers have been vetted CREST has rigorous exams. If you’re in a regulated industry finance, government, utilities, using a CREST member company is often considered best practice and sometimes required for specific engagements e.g., CBEST tests require CREST approved suppliers. That said, there are competent providers who may not yet be CREST accredited but still have strong credentials like OSCP certified staff, or ex CLAS/CHECK consultants. For many private sector companies, what matters most is the skill of the tester and quality of work CREST is one way to gauge that, but not the only way. If a provider is not CREST accredited, ask about other signs of trust: Are they an NCSC CHECK service provider? Do their team leads have certifications or a strong portfolio? Also consider scale CREST accreditation is a must have if you want the broad assurance and formal process of a larger firm. But a smaller boutique might do excellent work without it, especially if led by well known experts. In summary: Use CREST as a differentiator when narrowing down choices, especially for high criticality tests. If two vendors are otherwise equal, the CREST member is the safer bet for quality. But don’t automatically dismiss a non CREST firm if they demonstrate excellence in other ways. Always weigh the full picture of expertise, not just one label.
Selecting the right penetration testing company is a key decision that can significantly impact your organization’s security posture. In this article, we’ve provided a comprehensive, neutral comparison of the top UK providers in 2025 from innovative boutiques like DeepStrike, to enterprise stalwarts like NCC Group, to compliance experts like Nettitude and beyond. Our goal is to equip you with a clear understanding of each option’s strengths and weaknesses, so you can make an informed, confident choice aligned with your needs.
Cyber threats will continue to evolve, but partnering with a trusted pentest provider helps ensure you find and fix vulnerabilities before attackers do. Remember that best is context dependent: the best provider for a small fintech startup may differ from the best for a government agency. Use the methodology and criteria we discussed as a guide to evaluate any vendor transparency, expertise, and track record are hallmarks of a provider you can trust. By focusing on factual research and avoiding hype, we hope this ranking has built your trust in the recommendations.
Ultimately, the right penetration testing partner will not only deliver a report, but also become a valuable ally in your ongoing security journey. With the UK’s threat landscape and regulatory demands in mind, the companies listed here are all capable allies. Take your time, ask questions, and choose the provider that instills the most confidence for your organization’s mission. An informed decision today will pay off in a stronger defense against tomorrow’s cyber attacks.
About the Author
Mohammed Khalil is a Cybersecurity Architect at DeepStrike, specializing in advanced penetration testing and offensive security operations. With certifications including CISSP, OSCP, and OSWE, he has led numerous red team engagements for Fortune 500 companies, focusing on cloud security, application vulnerabilities, and adversary emulation. His work involves dissecting complex attack chains and developing resilient defense strategies for clients in the finance, healthcare, and technology sectors.
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