Penetration Testing Companies in UK 2025 (Reviewed)

UK Penetration Testing Companies

• Threat landscape: 43% of UK businesses reported breaches in 2025 , compliance mandates make pentesting essential.
• DeepStrike leads UK: Modern PTaaS platform with continuous testing, real time dashboards, and free retesting.
• Key competitors: NCC Group enterprise scale, Pen Test Partners independent CREST experts, Bulletproof SMB/compliance focus, plus others.
• Coverage: Web, mobile, cloud, network, and red team assessments.
• Certifications & standards: CREST, CHECK, OSCP, PCI DSS, ISO 27001 mark quality and trust.
• Costs: £600-£3,000 per tester day Evalian, pricing varies by scope, depth black box vs. white box, and report detail.
• Market shift: Many providers now offer continuous pentesting platforms, blurring lines between one off audits and ongoing monitoring.

In 2025, UK organizations cannot afford to ignore cybersecurity. Nearly 43% of UK businesses reported at least one cyber attack or breach in the last year. A single high profile incident, like the recent Marks & Spencer attack, is estimated to have cost around £300 million in lost profit.

Penetration testing pen testing hiring ethical hackers to actively probe your systems is now a business imperative, not a luxury. Beyond finding hidden vulnerabilities, professional pentests satisfy strict compliance mandates e.g. PCI DSS 11.3, ISO 27001 and support cyber insurance requirements.

This guide reviews the top penetration testing companies in the UK. We’ll explain what modern pentesting covers see NIST SP 800 115 for the standard phases of a test, why it matters in 2025’s threat landscape, and how to choose a provider.

We compare leading UK firms from large consultancies to agile specialists highlighting their services, pricing models, certifications, and unique strengths. Whether you’re a large enterprise or an SMB, you’ll learn which pentest partner can best secure your web, mobile, cloud, and network infrastructure.

Why Penetration Testing Matters in 2025

As cyber attacks rise, pentesting is a critical defense. It goes beyond automated scanning by having skilled experts attempt real exploits. For example, a vulnerability scan might flag SQL Injection as possible, but a pentester will actively exploit it, showing how an attacker could compromise your database. In fact, vulnerability scanners often miss multi step or environment specific flaws human led pentesting validates which issues are truly dangerous.

Compliance and Risk: Regulations explicitly demand pentesting. PCI DSS v3.2.1 requires annual external and internal pentests see PCI DSS 11.3 penetration testing guide, while ISO 27001’s Annex A.12 mandates reviewing and improving security. Cyber insurers and regulators often check for CREST approved testers or NCSC CHECK status. In practice, most UK firms get at least one full pen test per year, often two, one external, one internal or adopt continuous pentesting as a service PTaaS for ongoing assurance.

Cybersecurity Context: Beyond compliance, real threats make proactive testing urgent. Attack methods are getting more sophisticated and automated see latest penetration testing statistics. For example, global data shows an average breach costs $4.4 million orders of magnitude higher than the typical pentest price. The UK pentesting market itself is growing, it was about $90 million USD in 2025 at a 17% CAGR, reflecting pentesting’s value in protecting data and reputation.

Pentest Scope: Today’s pentests cover a wide range, external network, internal network, cloud infrastructure, web and mobile apps, APIs, IoT/OT systems, wireless, and even social engineering or physical security. Modern providers often bundle red teaming full attack simulation with standard tests. You can choose black box tests with no internal info given vs white box source code/architecture provided depending on needs. Many vendors also offer integrations with DevSecOps tools, and free retesting of fixes with no surprise charges for revalidation.

In short, given the stakes in 2025 major breaches, tight audits, and cyber insurance, hiring a skilled pentesting company is essential. The rest of this article compares the top UK providers and shows how to evaluate them.

Top UK Penetration Testing Companies 2025

DeepStrike Modern, Fully Managed Pentesting

DeepStrike London/UK is a next generation pentest provider that blends heavy manual testing with a cloud based Penetration Testing as a Service PTaaS platform.

• Services: Provides penetration testing across networks external/internal, web and mobile apps, APIs, and cloud environments. Engagements emphasize human led testing over automation every project includes custom exploits and creative attack paths. Clients access a cloud PTaaS dashboard with Slack, Jira, and ServiceNow integration, plus detailed reports mapped to business risk. Includes free unlimited retesting of fixes for 12 months.
• Certifications & Compliance: Team holds advanced certifications including OSCP, OSWE, OSCE, OSWP, CISSP, GIAC GWAPT, and eCPPT. Reporting supports SOC 2, ISO 27001, HIPAA, and PCI DSS compliance. Currently pursuing CREST accreditation for UK market recognition.
• Clients: Popular with tech companies, scale ups, and enterprises seeking a balance of continuous security assurance and deep manual testing. Known for quick onboarding tests often start within 48 hours.
• Pricing: Offers tiered packages:
  • Basic one off engagements for quick audits.
  • Premium subscriptions for continuous coverage.
  • Startup friendly packages tailored to growing businesses.
• Key Strength: Founded by experts co authors of the Web Application Hacker’s Handbook, DeepStrike combines elite manual expertise with a PTaaS delivery model. Their methodology consistently finds vulnerabilities that automated tools and other vendors miss.

DeepStrike UK stands out as a next generation pentest provider that blends manual creativity with continuous PTaaS transparency. Ideal for fast moving organizations that need rapid onboarding, continuous security validation, and actionable reports mapped to compliance and real world risk.

NCC Group Enterprise Scale Security Leader

NCC Group Manchester HQ, FTSE 250 listed is one of the UK’s largest cybersecurity consultancies.

• Services: Offers a complete penetration testing portfolio, including external/internal networks, web and mobile apps, cloud infrastructure, IoT, wireless, and physical security assessments. Also provides advanced red and purple teaming, supported by 1,000+ research days annually to keep methodologies at the cutting edge.
• Certifications & Compliance: Fully CREST accredited and an NCSC CHECK provider approved for UK government pentests. Operates UKAS accredited labs ISO 17025 and holds ISO 27001 certification. Many consultants hold advanced credentials such as CREST CCT, the highest pentesting certification.
• Clients: Trusted by regulated industries including banking, defense, and government, as well as enterprises with complex, multi country infrastructures.
• Pricing: Positioned at the premium end of the market, reflecting scale, pedigree, and assurance requirements. Pricing aligns with large, bespoke enterprise engagements.
• Key Strength: With 2,200 employees globally and a FTSE 250 listing, NCC Group brings unmatched scale, credibility, and global reach. Capable of delivering the largest and most complex pentest scopes, they are widely seen as the go to provider for maximum assurance.

NCC Group stands out for its scale, pedigree, and deep expertise, making it the preferred partner for regulated enterprises and government clients. While pricing is premium, their research driven methodology, global footprint, and regulatory approvals ensure maximum assurance.

Pen Test Partners Expert Independent Specialists

Pen Test Partners PTP is a UK boutique 100+ staff founded in 2010, focused entirely on hands-on security testing.

• Services: Dedicated exclusively to hands-on security testing. Coverage includes web and mobile apps, APIs, networks, IoT/OT industrial systems, code reviews, wireless security, and advanced Red Team, CBEST, GBEST, and TIBER assessments. Also offers incident response and DFIR services. Provides a PTaaS portal for managing engagements, but emphasizes manual, deep dive analysis.
• Certifications & Compliance: Fully CREST accredited and NCSC CHECK certified qualified for UK government testing. Holds PCI QSA, Cyber Essentials Plus, and is licensed for CBEST/TIBER regulatory testing. Staff certifications include OSCP, OSWP, CISSP, and more.
• Clients: Strong presence in critical infrastructure sectors, including power grids, payment systems, airports, and nuclear facilities. Also serves enterprises requiring high assurance red team engagements.
• Pricing: Boutique level, project based pricing. Engagements are tailored to highly complex and sensitive environments, often requiring bespoke scoping.
• Key Strength: Known for independent expertise and persistence. With 100+ UK based staff, PTP’s veteran consultants frequently present at conferences and publish research on emerging threats. Clients highlight their thoroughness and determination in uncovering every possible attack path.

Pen Test Partners is a standout choice for organizations needing elite technical depth, independence, and UK based expertise. Their proven track record in ICS/SCADA, complex red team scenarios, and regulatory testing positions them as one of the UK’s most respected boutique pentest firms.

Nettitude LRQA Compliance Focused Consultancy

Nettitude, now part of Lloyd’s Register/LRQA is a large UK cyber firm known for blending technical testing with a strict compliance mindset.

• Services: Provides cloud, network, web/mobile, IoT, and OT pentests, as well as full red teaming. Often bundles testing with ISO 27001 and PCI DSS audit support, making them a one stop shop for regulated clients. Also delivers MDR services and security architecture reviews.
• Certifications & Compliance: Fully CREST accredited and NCSC CHECK certified, aligned with ISO 27001 standards through parent company LRQA Lloyd’s Register. Consultants hold GIAC, OSCP, and PCI QSA certifications, ensuring both technical and compliance credibility.
• Clients: Trusted by banks, government departments, maritime, energy, and other regulated industries where both security and audit readiness are critical.
• Pricing: Engagements are typically project based, often structured around compliance driven scopes. Pricing reflects the dual value of technical assurance plus audit ready documentation.
• Key Strength: Nettitude blends technical depth with compliance rigor. Known for professional, executive ready reporting and remediation guidance aligned to international standards. Excels when audit evidence ISO, PCI, Cyber Essentials Plus is just as important as security findings.

Nettitude is a strong choice for organizations that need penetration testing plus compliance alignment. Their dual focus on technical assurance and audit readiness makes them a preferred partner for highly regulated sectors where governance and standards carry equal weight to vulnerability discovery.

Bulletproof SME and Compliance Specialist

Bulletproof is a UK headquartered cybersecurity company serving clients from SMBs to enterprises.

• Services: Provides web, mobile, network, cloud, and social engineering tests, with additional red teaming capabilities. Core focus is compliance driven pentesting for frameworks like PCI DSS, ISO 27001, GDPR, SOC 2, and HIPAA. Clients manage findings via an online portal with prioritized vulnerabilities and recommended fixes.
• Certifications & Compliance: CREST accredited and ISO 27001 certified. Pentesters hold OSCP and similar qualifications. Frequently deliver Cyber Essentials Plus packages and GDPR DPIA support for UK specific compliance.
• Clients: Works with both SMBs and larger enterprises, though especially popular in the mid market segment where compliance validation is a key driver.
• Pricing: Offers SME friendly packages, including fixed scope deals and smaller project options. Designed for affordability and rapid delivery while still meeting CREST standards.
• Key Strength: Known for speed, accessibility, and customer service. Engagements can be launched quickly, with reports often delivered within days. Customers value their approachable team and emphasis on business impact over technical jargon.

Bulletproof is a solid contender for SMBs and mid market UK firms seeking affordable, compliance ready pentesting. With CREST accreditation, fast turnaround, and clear reporting, they combine credibility with convenience making them ideal for organizations that need practical, budget conscious testing.

Secarma Offensive Minded Red Teamers

Secarma Manchester, est. 2001 is a UK firm known for deeply offensive security testing.

• Services: Offers web, mobile, and infrastructure pentests, with a reputation for complex red team operations that blend digital, physical, and social engineering attacks. Provides a PTaaS model for organizations seeking continuous testing. Known for in house R&D and tool development e.g., the EndView implant.
• Certifications & Compliance: CREST accredited and NCSC CHECK approved. Consultants hold OSCP, GIAC Pentest, and related advanced certifications. Early contributor to UK CBEST and GBEST simulations.
• Clients: Frequently engaged by NHS, fintech firms, and the energy sector, as well as government and regulated industries requiring adversary level assurance.
• Pricing: Engagements are typically project based and priced for complex, adversary style testing scenarios, with continuous PTaaS options available for enterprise clients.
• Key Strength: Renowned for persistence and chained exploit discovery. Secarma’s methodology is based on the philosophy that we don't quit until every door and window is checked. Their ability to simulate determined adversaries makes them especially valuable for sensitive, high security environments.

Secarma is a strong choice for organizations facing sophisticated threat actors and needing deep, persistent red team engagements. Their attacker mindset, combined with creativity and advanced tooling, positions them among the UK’s most specialized offensive security firms.

Other Notable UK Pentesters

Beyond the leading providers highlighted above, several other firms contribute to the UK penetration testing ecosystem:

• Context Information Security now part of Accenture: Known for government and defense consulting, providing high assurance pentesting and red teaming.
• Specialized IoT testers: A handful of niche boutiques focus exclusively on IoT and embedded device security.
• BAE Systems Applied Intelligence: Brings defense grade methodologies into enterprise pentesting and red team projects.
• F Secure Consulting now WithSecure: Offers global consulting services with strong expertise in application and network testing.
• Kroll Redscan: Provides offensive testing and MDR services, often paired with incident response.

All above firms have proven track records. Smaller boutiques offer agility and deep focus on specific sectors, while global players deliver vast resources. Pricing is always project based. Consider the provider’s certification pedigree, methodology manual vs automated, black vs white box, and how well their services match your scope web, mobile, cloud, IoT, etc..

DeepStrike stands out for combining top tier pentesting expertise with a modern PTaaS delivery, clients get aggressive human led testing plus continuous monitoring and retesting. Enterprises seeking scale and maximum assurance may lean towards NCC or Nettitude, whereas others might choose Bulletproof or Secarma for their niche strengths. In all cases, the goal is the same, find vulnerabilities before attackers do.

How to Choose a Penetration Testing Provider

Selecting a pentesting firm is partly about technical depth and partly about fit. Here are key criteria and a simple checklist:

• Certifications & Accreditations: Look for CREST or CHECK membership, especially if your sector requires it. CREST certified companies have independently verified standards and processes. Check that lead testers hold strong certs OSCP, CISSP, CEH, etc.. Asking for sample reports can verify quality.
• Experience & Focus: Consider industry experience. Some firms specialize e.g. critical infrastructure Pen Test Partners is noted for OT/SCADA and CBEST/TIBER engagements, finance NCC Group’s long history in banking, or SMEs Bulletproof’s focus. Ensure they’ve tested similar technologies e.g. cloud platforms, mobile apps, IoT. Check public case studies if available.
• Methodology: A good pentester follows standards OWASP, PTES, NIST SP 800 115, etc. see 48†L131 L139 and uses mostly manual testing, not just automated scans. Ask about black box vs white box approach and tools used e.g. Burp Suite, Metasploit, Nessus. Beware overly cheap quotes as one industry guide warns, a £XX price may cover only an automated scan, not a full manual pentest. Our penetration testing RFP writing guide can help structure your requirements.
• Scope & Reporting: Define scope clearly web apps, network, APIs, social engineering, etc.. Check if internal vs external coverage, and whether mobile or cloud are included e.g. mobile app pentesting solution anchors. Evaluate their reporting quality, does it include an executive summary, risk ratings, and actionable remediation advice? Many UK firms now include at least one free retest of fixes. If continuous testing is important, ask if they offer a dashboard driven PTaaS platform see continuous penetration testing platform.
• Cost & Turnaround: Get detailed quotes day rates or fixed price and clarify inclusions. Day rates in the UK typically range from about £600-£3,000 depending on tester seniority and company. A small 3-5 day web test might cost £3k-£7k, whereas a 2-3 week full scope engagement could be £15k-£30k or more. For SMEs, look for packaged deals some firms offer startup/SMB rates see our penetration testing for startups and SMBs. Prioritize what systems are most critical to test first. Remember, a thorough pentest especially for compliance is an investment average breaches cost millions, far more than a test.
• Communication & Support: Pentesting isn’t a one off. You want a partner who explains findings clearly, is responsive to questions, and helps with post test planning. Many clients value vendors that offer quick project kickoff weeks, not months and hands on debrief calls. Read reviews or ask for references.

By following these steps, scoping your needs, checking credentials, comparing services and pricing, and asking the right questions. The next section describes some of the top UK providers and what makes them unique.

Penetration Testing Costs in the UK

Pricing varies widely by project. As noted above, day rates in the UK range roughly from £600 up to £3,000 per tester day. Total cost depends on: scope number and complexity of systems, depth internal vs external, black box vs white box, and expertise senior pentesters cost more. For example:

• A basic 2-3 day external network or web app test might be £3k-£6k.
• A mid sized 1 week project covering multiple apps and network segments could be £7k-£15k.
• A comprehensive multi week engagement e.g. full red team or large corporate network often runs into the £20k-£30k+ range.

Many firms will quote either a fixed price or a number of days. Make sure the quote lists deliverables report, retest policy, support. Some providers like DeepStrike bundle unlimited retesting of verified fixes for a set period. Others may offer penetration testing quote checklists and cost calculators to ensure transparency. For startups and SMBs, look for tailored packages, some vendors market quick turnaround, fixed scope scans plus one app tests in the £2k-£5k range.

Emphasize key assets in your scope. It’s better to get one high quality test on your crown jewels than a broad but shallow scan. Ensure you allocate budget not just for the test itself, but also for timely remediation and follow up. Remember, the average cost of a single data breach is still on the order of millions spending a few thousand on prevention is money well spent.

The UK pentesting market is rich with capable providers. From DeepStrike’s modern PTaaS platform and expert red teamers, to the massive scale of NCC Group, the deep expertise of Pen Test Partners, and the SMB focus of firms like Bulletproof each has a place.

Your choice depends on your organization’s size, industry, budget and risk profile. Key takeaways, look for certified expertise CREST, CHECK, OSCP, etc., clear methodology automated scan vs human test, and strong post test support reporting, retesting.

Ready to Strengthen Your Defenses? The threats of 2025 demand more than just awareness, they require readiness. If you’re looking to validate your security posture, identify hidden risks, or build a resilient defense strategy, DeepStrike is here to help. Our team of practitioners provides clear, actionable guidance to protect your business.

Explore our penetration testing services to see how we can uncover vulnerabilities before attackers do. Drop us a line, we’re always ready to dive in.

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 finance, healthcare, and technology sectors.

FAQs

• What’s the difference between a penetration test and a vulnerability assessment?

A penetration test is an active attack simulation, whereas a vulnerability assessment is a primarily automated scan. A vuln assessment will identify known issues e.g. missing patches or misconfigurations and produce a list of potential weaknesses. A penetration test goes further ethical hackers try to exploit vulnerabilities to determine impact. Think of a vuln scan as a health check up, and a pentest as a realistic attack drill. For example, a scan might flag SQL Injection possible in a web app. In a pentest, the tester will attempt that injection and, if successful, show exactly how an attacker could use it to compromise data. In practice, organizations often do both, routine vulnerability scans for obvious flaws and periodic pentests for deep assurance. In fact, many pentest providers include an automated scan phase as part of their methodology.

• How much does penetration testing cost in the UK?

Costs vary by scope and complexity. UK pentesters typically charge £600-£3,000 per tester day. A small project e.g. a 3 day external web test might be £3k-£5k total, while a medium enterprise test 15-20 days across apps and networks could be £15k-£30k. Day rates depend on tester seniority and firm reputation CREST certified experts often command higher rates. Many firms give custom quotes after you define scope. Remember, quality is key: a thorough pentest that finds real vulnerabilities is far cheaper than the cost of a breach, often millions. Always compare what’s included in the number of IPs/apps, internal vs external, deliverables and follow a penetration testing quote checklist to avoid surprises.

• Do we need a CREST certified penetration testing company?

It’s not legally mandatory for most businesses, but it’s strongly recommended. CREST accreditation means the company has passed rigorous audits and that its testers meet industry standards. In the UK, many regulations and contracts explicitly prefer or require a CREST approved vendor. Choosing a CREST certified firm ensures a baseline of competence. That said, excellent testers can work outside CREST too just to verify their individual experience and certifications OSCP, CISSP, etc.. A safe rule of thumb for compliance heavy sectors finance, healthcare, government, go CREST certified to check all boxes.

• How often should we conduct penetration testing?

At a minimum annually or after significant changes. Standards like ISO 27001 and PCI DSS require at least yearly tests and after any major network/app upgrade. Many UK businesses test twice a year once for external assets and once internal, or one broad test and one targeted e.g. mobile app. There’s a trend toward continuous testing doing smaller pentests on each software release or as a quarterly service PTaaS. If you have a fast DevOps cycle, consider integrating pentests into your pipeline. Frequency should match risk high profile industries finance, energy, healthcare often test more often, while smaller orgs start with yearly tests. The key is to consistently schedule it so security remains a priority, not an afterthought.

• Will penetration testing disrupt our operations?

A well planned penetration test should cause minimal disruption. Professional testers coordinate with you to avoid outages for example, they’ll often run noisy scans or exploits outside business hours, or use a staging environment if available. Before starting, you’ll set rules of engagement e.g. critical systems off limits, bandwidth limits. Testers continuously monitor systems and can pause if anything breaks. In rare cases a test might overload an unstable server, but that risk is mitigated by careful scope selection and communication. Generally, a pentest is far less disruptive than a real breach. Reputable firms emphasize a safe approach to attack hard but safely, since their goal is to improve security, not cause downtime.

• What happens after a penetration test?

After testing, you’ll receive a detailed report, an executive summary and technical section. It lists each finding with severity, evidence screenshots or exploit output, and recommended remediation steps. Your team should address the vulnerabilities, some fixes may be quick patches, config changes, others may need code or architecture updates. The pentesters will usually offer a debrief call to explain the issues. Many providers include a free retest of any fixed vulnerabilities typically within a few months to verify closures. Once all critical issues are resolved and documented, your security posture is greatly improved. Audit trails of the report and fixes can also help when demonstrating compliance. Then, planning the next test security is an ongoing journey.

• Can small businesses in the UK afford penetration testing?

Absolutely and they really should budget for it. Cyberattacks are not limited to big companies, in fact, a high percentage of SMEs face breaches. Many pentest firms now offer scaled down packages or startup discounts. For example, an SMB might only test its main website and a basic internal scan 2-3 days total, costing in the low thousands of pounds. Some companies including DeepStrike allow payment plans or multi phase testing to spread cost. Think of it this way, the financial and reputational damage from a single breach or a regulatory fine far exceeds the cost of a test. Plus, having a pentest report can boost your credibility with partners or insurers. A modest security investment now can prevent a catastrophe later.