Network Penetration Testing Providers

Network penetration testing evaluates the security of your organisation's network infrastructure by simulating attacks against internal and external network assets. External network pen testing targets internet-facing systems including firewalls, VPN gateways, mail servers, DNS servers, and web servers to identify vulnerabilities that could allow an attacker to gain initial access.

Internal network pen testing simulates an attacker who has already gained a foothold inside the network, testing for lateral movement opportunities, privilege escalation paths, misconfigured services, weak credentials, and unpatched systems. Testers use tools and techniques similar to those used by real adversaries, including port scanning, service enumeration, vulnerability exploitation, and credential attacks.

Network pen testing is critical for organisations of all sizes and is required by compliance frameworks including PCI DSS, NIST CSF, ISO 27001, and Cyber Essentials. Regular testing helps organisations understand their actual security posture and prioritise remediation efforts based on real risk.

29 providers
Top UK ProviderElite TestersResearch-Driven
SECFORCE logo

SECFORCE

Leading UK offensive security consultancy based in Canary Wharf, delivering CREST-accredited penetration testing and adversary simulation to organisations with the most demanding security requirements.

95
Score
LOCLondon, United Kingdom
Web ApplicationNetworkMobile App+9
CRESTISO 27001Cyber Essentials
Best UK ProviderBest for EnterpriseResearch Leaders
NCC Group logo

NCC Group

Global cybersecurity consultancy with CREST, CHECK, and CBEST accreditation, renowned for deep technical research and comprehensive penetration testing services.

75
Score
LOCManchester, United Kingdom
Web ApplicationNetworkMobile App+13
CRESTCHECKCBEST+6
Nettitude logo

Nettitude

CREST, CHECK, and CBEST accredited UK consultancy within Lloyd's Register, delivering premium penetration testing for government and critical infrastructure.

64
Score
LOCLondon, United Kingdom
Web ApplicationNetworkMobile App+10
CRESTCHECKCBEST+2
Best for Mid-MarketBest for Financial Services
NetSPI logo

NetSPI

Leading penetration testing firm with the Resolve platform for continuous attack surface management, trusted by nine of the top ten US banks.

60
Score
LOCMinneapolis, Minnesota, United States
Web ApplicationNetworkCloud+8
SOC 2ISO 27001CREST
Trustwave logo

Trustwave

Global managed security provider with the elite SpiderLabs penetration testing team and deep PCI DSS compliance expertise.

57
Score
LOCChicago, Illinois, United States
Web ApplicationNetworkMobile App+7
PCI QSAISO 27001SOC 2+1
Bridewell logo

Bridewell

Fast-growing CREST and CHECK-accredited UK cybersecurity consultancy with deep expertise in critical national infrastructure sectors.

56
Score
LOCBristol, United Kingdom
Web ApplicationNetworkCloud+7
CRESTCHECKISO 27001+1
Pentest People logo

Pentest People

CREST and CHECK-accredited UK penetration testing firm with an innovative SecurePortal platform and transparent pricing for mid-market organizations.

55
Score
LOCLeeds, United Kingdom
Web ApplicationNetworkMobile App+7
CRESTCHECKCyber Essentials Plus+1
Mandiant logo

Mandiant

World-renowned cybersecurity firm now part of Google Cloud, delivering threat intelligence-led penetration testing and red teaming informed by front-line incident response experience.

53
Score
LOCReston, Virginia, United States
Red TeamingPurple TeamingNetwork+6
SOC 2ISO 27001FedRAMP 3PAO
Best OverallElite TestersResearch Pioneers
Bishop Fox logo

Bishop Fox

Premier US-based offensive security firm known for elite penetration testers, cutting-edge research, and the Cosmos continuous attack surface management platform.

50
Score
LOCTempe, Arizona, United States
Web ApplicationNetworkMobile App+8
SOC 2OSCP Employer
Rapid7 logo

Rapid7

Creators of Metasploit offering enterprise penetration testing integrated with their comprehensive vulnerability management and security operations platform.

50
Score
LOCBoston, Massachusetts, United States
Web ApplicationNetworkMobile App+7
SOC 2ISO 27001
Coalfire logo

Coalfire

Compliance-focused cybersecurity advisory firm and FedRAMP 3PAO specializing in penetration testing that meets stringent regulatory requirements.

50
Score
LOCWestminster, Colorado, United States
Web ApplicationNetworkCloud+5
SOC 2FedRAMP 3PAOPCI QSA+1
WithSecure logo

WithSecure

Leading European cybersecurity firm offering penetration testing with deep expertise in EU regulatory compliance including GDPR, NIS 2, and TIBER-EU.

49
Score
LOCHelsinki, Finland
Web ApplicationNetworkCloud+7
CRESTISO 27001
Claranet logo

Claranet

CREST and CHECK-accredited European managed services provider delivering penetration testing with deep infrastructure and cloud hosting expertise.

48
Score
LOCLondon, United Kingdom
Web ApplicationNetworkMobile App+5
CRESTCHECKISO 27001+1
HackerOne logo

HackerOne

World's largest ethical hacker platform with over one million researchers, offering bug bounties and structured penetration testing to the US DoD and Fortune 500.

47
Score
LOCSan Francisco, California, United States
Web ApplicationAPIMobile App+3
SOC 2ISO 27001FedRAMP 3PAO
Integrity360 logo

Integrity360

CREST-accredited pan-European cybersecurity services provider delivering penetration testing and managed security from Dublin with a strong UK and Ireland presence.

44
Score
LOCDublin, Ireland
Web ApplicationNetworkMobile App+6
CRESTISO 27001SOC 2
Black Hills Information Security logo

Black Hills Information Security

Community-driven penetration testing firm known for free security education, open-source tools, Wild West Hackin' Fest, and practical offensive security services.

44
Score
LOCSpearfish, South Dakota, United States
NetworkWeb ApplicationSocial Engineering+5
SOC 2
SEC Consult logo

SEC Consult

Leading European cybersecurity consultancy from Vienna with a prolific vulnerability research program and deep expertise in IoT and embedded systems security.

43
Score
LOCVienna, Austria
Web ApplicationNetworkMobile App+7
ISO 27001
CrowdStrike logo

CrowdStrike

Global cybersecurity leader leveraging world-class threat intelligence from the Falcon platform to deliver intelligence-led penetration testing and red teaming.

43
Score
LOCAustin, Texas, United States
Red TeamingNetworkWeb Application+5
SOC 2ISO 27001
IOActive logo

IOActive

Elite boutique security consultancy specializing in IoT, SCADA/ICS, embedded systems, and hardware security research with world-renowned researchers.

42
Score
LOCSeattle, Washington, United States
Web ApplicationNetworkIoT+7
OSCP Employer
Secureworks logo

Secureworks

Dell Technologies-backed cybersecurity firm with elite Counter Threat Unit intelligence informing enterprise penetration testing and adversary simulation.

41
Score
LOCAtlanta, Georgia, United States
Web ApplicationNetworkCloud+7
SOC 2ISO 27001
Rhino Security Labs logo

Rhino Security Labs

Cloud security penetration testing specialists known for the Pacu AWS exploitation framework and deep expertise across AWS, Azure, and GCP environments.

41
Score
LOCSeattle, Washington, United States
CloudWeb ApplicationNetwork+4
SOC 2
Praetorian logo

Praetorian

Offensive security firm founded by former DoD professionals, offering elite penetration testing and the Chariot continuous attack surface management platform.

40
Score
LOCAustin, Texas, United States
Web ApplicationNetworkCloud+7
SOC 2
Offensive Security logo

Offensive Security

Creators of OSCP, Kali Linux, and Exploit-DB, offering elite penetration testing services from the team that trains the world's ethical hackers.

40
Score
LOCNew York, New York, United States
Web ApplicationNetworkRed Teaming+5
OSCP Employer
Bugcrowd logo

Bugcrowd

Leading crowdsourced security platform offering managed bug bounty programs and crowd-powered penetration testing with hundreds of thousands of ethical hackers.

40
Score
LOCSan Francisco, California, United States
Web ApplicationAPIMobile App+3
SOC 2ISO 27001
Synack logo

Synack

FedRAMP-authorized crowdsourced penetration testing platform combining vetted elite hackers with AI-powered Hydra technology for continuous security testing.

39
Score
LOCRedwood City, California, United States
Web ApplicationNetworkAPI+4
FedRAMP 3PAOSOC 2
Aon Cyber Solutions logo

Aon Cyber Solutions

Cybersecurity consulting division of global insurance leader Aon, uniquely combining penetration testing with cyber risk quantification and insurance expertise.

36
Score
LOCLondon, United Kingdom
Web ApplicationNetworkCloud+5
ISO 27001SOC 2
Securin logo

Securin

Vulnerability intelligence-driven penetration testing firm providing contextual security assessments informed by threat actor exploitation data and ransomware tracking.

34
Score
LOCAlbuquerque, New Mexico, United States
Web ApplicationNetworkAPI+3
SOC 2
BreachLock logo

BreachLock

Cloud-based Penetration Testing as a Service platform combining AI-driven automation with expert manual testing at accessible price points.

33
Score
LOCNew York, New York, United States
Web ApplicationNetworkAPI+4
SOC 2ISO 27001
Cobalt logo

Cobalt

Pioneer of Pentest as a Service, delivering fast, platform-based penetration testing with a vetted global community of security researchers.

29
Score
LOCSan Francisco, California, United States
Web ApplicationNetworkAPI+2
SOC 2

Network Penetration Testing FAQs

What is the difference between external and internal network pen testing?+

External testing targets internet-facing systems to find ways an attacker could breach the perimeter. Internal testing simulates an attacker already inside the network, testing for lateral movement and privilege escalation.

Will network pen testing cause downtime?+

Professional penetration testers take precautions to avoid service disruption. Testing is typically scheduled during agreed windows and testers avoid denial-of-service attacks unless specifically requested and authorised.

What do I need to provide for a network pen test?+

For external testing, provide IP ranges and domains in scope. For internal testing, provide network access (VPN or on-site), IP ranges, and any systems to exclude. Clear scoping and rules of engagement should be agreed in advance.