# 30 leading cybersecurity companies in the Hauts-de-Seine department

Tamtam tracks 154 cybersecurity companies headquartered in the Hauts-de-Seine department. This list ranks the 30 largest by number of employees on LinkedIn, led by Orange, Thales and Astek. Their median headcount is 559. Half of them were founded in 2001 or later. The most common headquarters are Boulogne-Billancourt (4), Puteaux (4) and Courbevoie (3).

These companies are primarily large and mid-sized firms in the Hauts-de-Seine department, predominantly focused on IT services and consulting, with a strong emphasis on cybersecurity and telecommunications. Several companies also operate in defense, aerospace, and environmental services. The concentration of headquarters in cities like Nanterre, Issy-les-Moulineaux, and Boulogne-Billancourt is notable.

Key players include Orange, a global telecommunications operator; Thales, specializing in cybersecurity and defense; Astek, providing IT services for digital transformation; and Orange Cyberdefense, a leading security provider. Other significant firms are Dekra France, offering inspection and certification services, and CS GROUP, which designs and maintains critical systems.

🇫🇷 Hauts-de-Seine · 30 companies · Updated Nov 11, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Orange](https://www.tamtam.ai/c/orange-issy-les-moulineaux) (orange.com)<br>A leading global telecommunications operator offering services to millions of customers and multinational companies across 26 countries | Telecommunications | 🇫🇷 Issy-les-Moulineaux | 146,935 |  |
| 2 | [Thales](https://www.tamtam.ai/c/thales) (thalesgroup.com)<br>Multinational specializing in cybersecurity, defense, aerospace, digital identity, and secure communications for governments and industries. | Defense and Space Manufacturing | 🇫🇷 Meudon | 65,031 |  |
| 3 | [Astek](https://www.tamtam.ai/c/astek) (astekgroup.fr)<br>Supports clients with high-value service, deep technical expertise across technology, operations, and engineering, focusing on sustainable digital transformation with humans at the core. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 6,035 | 1988 |
| 4 | [Orange Cyberdefense](https://www.tamtam.ai/c/orange-cyberdefense) (orangecyberdefense.com)<br>Expert cybersecurity business unit of the Orange Group. They are a leading security provider, striving to build a safer digital society. | IT Services and IT Consulting | 🇫🇷 Nanterre | 4,274 |  |
| 5 | [Dekra France](https://www.tamtam.ai/c/dekra-france) (dekra.fr)<br>Inspection, certification, risk management, audits, training, and consulting services for automotive, transport, industry, environment, and safety sectors. | Environmental Services | 🇫🇷 Le Plessis Robinson | 3,188 | 1925 |
| 6 | [CS GROUP](https://www.tamtam.ai/c/cs-group) (cs-soprasteria.com)<br>Designs, builds, deploys, and maintains critical systems with innovative solutions and products, ensuring operational efficiency and security for client missions. | IT Services and IT Consulting | 🇫🇷 Le Plessis Robinson | 2,968 | 1968 |
| 7 | [SPIE ICS](https://www.tamtam.ai/c/spie-ics) (spie.fr)<br>Supports digital transformation for businesses with ICT solutions, providing expertise in IT infrastructure, cloud, cybersecurity, and data & IoT for enhanced performance and user well-being. | IT Services and IT Consulting | 🇫🇷 Malakoff | 2,930 | 2001 |
| 8 | [SCC France](https://www.tamtam.ai/c/scc-france) (scc.com)<br>Provides comprehensive IT solutions, including cybersecurity, digital workplace, and hybrid infrastructure, enabling businesses to optimize operations and achieve their goals. | IT Services and IT Consulting | 🇫🇷 Nanterre | 1,422 | 1975 |
| 9 | [NXO France](https://www.tamtam.ai/c/nxo-france) (nxo.eu)<br>Independent leader in French Telecom integration, undertaking complex projects, anticipating customer needs, attracting talent, and focusing on well-done work. | IT Services and IT Consulting | 🇫🇷 Puteaux | 1,200 |  |
| 10 | [Axians France](https://www.tamtam.ai/c/axians-france) (axians.fr)<br>Supports clients with digital infrastructure and solutions, covering applications, data, networks, cloud, telecom, and cybersecurity through consulting, design, integration, and services. | IT Services and IT Consulting | 🇫🇷 Nanterre | 1,137 | 1999 |
| 11 | [Nomios Group](https://www.tamtam.ai/c/nomios-group) (nomios.com)<br>Designs, secures, and manages digital infrastructures, developing innovative cybersecurity and networking solutions through consulting, managed, and professional services for organizations. | Computer and Network Security | 🇫🇷 Boulogne-Billancourt | 887 | 2004 |
| 12 | [I-TRACING](https://www.tamtam.ai/c/i-tracing) (i-tracing.com)<br>This company offers comprehensive cybersecurity services globally, managing cyber risks, anticipating threats, ensuring system security, and providing rapid incident response to minimize attack consequences. | Computer and Network Security | 🇫🇷 Courbevoie | 683 | 2005 |
| 13 | [oXya](https://www.tamtam.ai/c/oxya) (oxya.com)<br>Leading provider of SAP technical services, cloud solutions, and hosting for midsize and global organizations, enhancing efficiency and flexibility of SAP infrastructure worldwide | IT Services and IT Consulting | 🇫🇷 Issy-les-Moulineaux | 586 |  |
| 14 | [Devoteam \| Google Cloud Partner](https://www.tamtam.ai/c/devoteam-google-cloud-partner) (gcloud.devoteam.com)<br>Provides innovative Google Cloud solutions across AI, IT modernization, security, and work transformation, with expertise in migrating users and assisting organizations. | IT Services and IT Consulting | 🇫🇷 Levallois-Perret | 579 |  |
| 15 | [Nexpublica](https://www.tamtam.ai/c/nexpublica) (nexpublica.com)<br>Develops innovative, secure software solutions for public, parapublic, and private sectors, supporting over 4,000 public and 1,200 private organizations. | Software Development | 🇫🇷 Clichy | 559 |  |
| 16 | [ChapsVision](https://www.tamtam.ai/c/chapsvision) (chapsvision.com)<br>French software company specializing in data intelligence and AI, providing industry-specific solutions for diverse sectors, supporting digital transformation globally. | Software Development | 🇫🇷 Suresnes | 558 | 2019 |
| 17 | [Paritel](https://www.tamtam.ai/c/paritel) (paritel.fr)<br>Paritel, a telecom operator for small businesses, prioritizes performance and individual talent while fostering teamwork and career development for its 700 employees | Telecommunications | 🇫🇷 Bois-Colombes | 501 | 1991 |
| 18 | [Hervé Schauer Consultants (HSC)](https://www.tamtam.ai/c/herve-schauer-consultants-hsc) (hs2.fr)<br>Provides information security consulting, audits, penetration tests, risk management, and training services to secure diverse infrastructures and systems. | Computer and Network Security | 🇫🇷 Neuilly-sur-Seine | 500 | 1989 |
| 19 | [Equans Digital](https://www.tamtam.ai/c/equans-digital) (equans-digital.com)<br>Connects operational and information technology systems to structure infrastructure data, improving energy efficiency, asset availability, and security through cybersecurity and applied artificial intelligence. | IT Services and IT Consulting | 🇫🇷 Courbevoie | 499 |  |
| 20 | [Thales Cybersecurity Services](https://www.tamtam.ai/c/thales-cybersecurity-services) (thalesgroup.com)<br>Delivering cybersecurity products and services. Protecting organizations by identifying, detecting, and responding to cyber threats. Specializing in data security and digital infrastructure protection for diverse sectors. | Computer and Network Security | 🇫🇷 Meudon | 495 | 2018 |
| 21 | [Linkt](https://www.tamtam.ai/c/linkt) (linkt.fr)<br>Provides managed services, telecom, and cybersecurity expertise for mid-sized and large companies, and local authorities, to optimize and secure their digital infrastructure. | Telecommunications | 🇫🇷 Puteaux | 463 | 2016 |
| 22 | [METSYS](https://www.tamtam.ai/c/metsys) (metsys.fr)<br>Advises clients on cybersecurity, infrastructure, and cloud solution design and implementation. Over 500 employees across France, 93.2M in revenue. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 435 | 2011 |
| 23 | [Stormshield](https://www.tamtam.ai/c/stormshield) (stormshield.com)<br>Provides certified cybersecurity solutions for critical infrastructure, sensitive data, and operational environments to ensure cyber-serenity for clients globally. | Computer and Network Security | 🇫🇷 Issy-les-Moulineaux | 433 | 2014 |
| 24 | [Almond](https://www.tamtam.ai/c/almond) (almond.eu)<br>Formed from NetXP and Provadys, positioned as a major independent French player in audit and consulting for Cybersecurity, Cloud, and Infrastructure. | IT Services and IT Consulting | 🇫🇷 Sèvres | 424 | 2006 |
| 25 | [Devoteam \| Cyber Trust](https://www.tamtam.ai/c/devoteam-cyber-trust) (devoteam.com)<br>Empowering clients to protect digital transformation by managing risks and deploying innovative cybersecurity solutions, ensuring resilience in the digital age | IT Services and IT Consulting | 🇫🇷 Levallois-Perret | 374 | 1995 |
| 26 | [ADENTIS](https://www.tamtam.ai/c/adentis) (adentis.fr)<br>High-tech consulting company developing software and embedded systems for digital TV, telecom, medical electronics, defense, and aeronautics. Research lab. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 362 | 2000 |
| 27 | [Avanquest](https://www.tamtam.ai/c/avanquest) (avanquestgroup.com)<br>A leading software publisher offering PDF, Security, and Photo products, utilizing cutting edge technology to enhance user experience worldwide | Software Development | 🇫🇷 Courbevoie | 340 | 1984 |
| 28 | [Cloud Temple](https://www.tamtam.ai/c/cloud-temple) (cloud-temple.com)<br>Provides IT transformation, hosting, and outsourcing for critical business applications. Guides customers from conception to maintenance across various IT verticals, specializing in private cloud. | IT Services and IT Consulting | 🇫🇷 Puteaux | 310 | 2017 |
| 29 | [NEXTEDIA](https://www.tamtam.ai/c/nextedia) (nextedia.com)<br>The Nextedia Group specializes in Cybersecurity, Cloud, Digital Workspace, and Customer Experience, providing expertise and solutions to large companies across various sectors | IT Services and IT Consulting | 🇫🇷 Puteaux | 305 |  |
| 30 | [EfficientIP](https://www.tamtam.ai/c/efficientip) (efficientip.com)<br>Offers network security and automation, specializing in DNS-DHCP-IPAM (DDI), ensuring reliable, agile, and secure IP infrastructure for business continuity and application access. | Computer and Network Security | 🇫🇷 La Garenne-Colombes | 269 | 2004 |

## How this list is built

Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 11, 2026.

## More company lists in the Hauts-de-Seine department

- [The largest companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/largest-companies-hauts-de-seine) (5,160)
- [Multinational companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/multinational-companies-hauts-de-seine) (1,231)
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- [Professional services firms in the Hauts-de-Seine department](https://www.tamtam.ai/l/professional-services-firms-hauts-de-seine) (629)
- [Consulting firms in the Hauts-de-Seine department](https://www.tamtam.ai/l/consulting-firms-hauts-de-seine) (563)
- [Companies with in-house R&D in the Hauts-de-Seine department](https://www.tamtam.ai/l/r-and-d-companies-hauts-de-seine) (510)
- [SaaS companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/saas-companies-hauts-de-seine) (389)
- [Business Consulting and Services companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/business-consulting-and-services-companies-hauts-de-seine) (304)
- [Software Development companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/software-development-companies-hauts-de-seine) (301)
- [Retail chains in the Hauts-de-Seine department](https://www.tamtam.ai/l/retail-chains-hauts-de-seine) (292)
- [Manufacturers in the Hauts-de-Seine department](https://www.tamtam.ai/l/manufacturers-hauts-de-seine) (285)
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- [Marketing and communications agencies in the Hauts-de-Seine department](https://www.tamtam.ai/l/marketing-agencies-hauts-de-seine) (235)
- [Subscription businesses in the Hauts-de-Seine department](https://www.tamtam.ai/l/subscription-businesses-hauts-de-seine) (228)
- [Hardware manufacturers in the Hauts-de-Seine department](https://www.tamtam.ai/l/hardware-companies-hauts-de-seine) (199)
- [Financial services firms in the Hauts-de-Seine department](https://www.tamtam.ai/l/financial-services-firms-hauts-de-seine) (198)
- [Companies with a mobile app in the Hauts-de-Seine department](https://www.tamtam.ai/l/companies-with-mobile-app-hauts-de-seine) (189)
- [Critical infrastructure operators in the Hauts-de-Seine department](https://www.tamtam.ai/l/critical-infrastructure-operators-hauts-de-seine) (169)
- [AI companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/ai-companies-hauts-de-seine) (159)
- [Education providers in the Hauts-de-Seine department](https://www.tamtam.ai/l/education-companies-hauts-de-seine) (159)
- [Distributors and wholesalers in the Hauts-de-Seine department](https://www.tamtam.ai/l/distributors-and-wholesalers-hauts-de-seine) (154)
- [Recruitment and staffing agencies in the Hauts-de-Seine department](https://www.tamtam.ai/l/recruitment-agencies-hauts-de-seine) (152)
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## The same list elsewhere in France

- [Cybersecurity companies in France](https://www.tamtam.ai/l/cybersecurity-companies-france) (958)
- [Cybersecurity companies in Île-de-France](https://www.tamtam.ai/l/cybersecurity-companies-ile-de-france) (525)
- [Cybersecurity companies in Auvergne-Rhône-Alpes](https://www.tamtam.ai/l/cybersecurity-companies-auvergne-rhone-alpes) (91)
- [Cybersecurity companies in Occitanie](https://www.tamtam.ai/l/cybersecurity-companies-occitanie) (49)
- [Cybersecurity companies in Provence-Alpes-Côte d'Azur](https://www.tamtam.ai/l/cybersecurity-companies-provence-alpes-cote-dazur) (48)
- [Cybersecurity companies in the Rhône department](https://www.tamtam.ai/l/cybersecurity-companies-rhone) (48)
- [Cybersecurity companies in Hauts-de-France](https://www.tamtam.ai/l/cybersecurity-companies-hauts-de-france) (44)
- [Cybersecurity companies in Grand Est](https://www.tamtam.ai/l/cybersecurity-companies-grand-est) (40)
- [Cybersecurity companies in Brittany](https://www.tamtam.ai/l/cybersecurity-companies-brittany) (37)
- [Cybersecurity companies in the Bouches-du-Rhône department](https://www.tamtam.ai/l/cybersecurity-companies-bouches-du-rhone) (36)
- [Cybersecurity companies in Nouvelle-Aquitaine](https://www.tamtam.ai/l/cybersecurity-companies-nouvelle-aquitaine) (35)
- [Cybersecurity companies in the Nord department](https://www.tamtam.ai/l/cybersecurity-companies-nord) (30)
- [Cybersecurity companies in Pays de la Loire](https://www.tamtam.ai/l/cybersecurity-companies-pays-de-la-loire) (28)
- [Cybersecurity companies in the Haute-Garonne department](https://www.tamtam.ai/l/cybersecurity-companies-haute-garonne) (27)
- [Cybersecurity companies in the Ille-et-Vilaine department](https://www.tamtam.ai/l/cybersecurity-companies-ille-et-vilaine) (25)
- [Cybersecurity companies in the Yvelines department](https://www.tamtam.ai/l/cybersecurity-companies-yvelines) (25)
- [Cybersecurity companies in Paris](https://www.tamtam.ai/l/cybersecurity-companies-paris) (290)

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Source: https://www.tamtam.ai/l/cybersecurity-companies-hauts-de-seine