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.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
Orangeorange.com
A leading global telecommunications operator offering services to millions of customers and multinational companies across 26 countries |
146,935 | |||
| 2 |
Thalesthalesgroup.com
Multinational specializing in cybersecurity, defense, aerospace, digital identity, and secure communications for governments and industries. |
65,031 | |||
| 3 |
Astekastekgroup.fr
Supports clients with high-value service, deep technical expertise across technology, operations, and engineering, focusing on sustainable digital transformation with humans at the core. |
6,035 | |||
| 4 |
Orange Cyberdefenseorangecyberdefense.com
Expert cybersecurity business unit of the Orange Group. They are a leading security provider, striving to build a safer digital society. |
4,274 | |||
| 5 |
Dekra Francedekra.fr
Inspection, certification, risk management, audits, training, and consulting services for automotive, transport, industry, environment, and safety sectors. |
3,188 | |||
| 6 |
CS GROUPcs-soprasteria.com
Designs, builds, deploys, and maintains critical systems with innovative solutions and products, ensuring operational efficiency and security for client missions. |
2,968 | |||
| 7 | 2,930 | ||||
| 8 |
SCC Francescc.com
Provides comprehensive IT solutions, including cybersecurity, digital workplace, and hybrid infrastructure, enabling businesses to optimize operations and achieve their goals. |
1,422 | |||
| 9 |
NXO Francenxo.eu
Independent leader in French Telecom integration, undertaking complex projects, anticipating customer needs, attracting talent, and focusing on well-done work. |
1,200 | |||
| 10 |
Axians Franceaxians.fr
Supports clients with digital infrastructure and solutions, covering applications, data, networks, cloud, telecom, and cybersecurity through consulting, design, integration, and services. |
1,137 | |||
| 11 |
Nomios Groupnomios.com
Designs, secures, and manages digital infrastructures, developing innovative cybersecurity and networking solutions through consulting, managed, and professional services for organizations. |
887 | |||
| 12 |
I-TRACINGi-tracing.com
This company offers comprehensive cybersecurity services globally, managing cyber risks, anticipating threats, ensuring system security, and providing rapid incident response to minimize attack consequences. |
683 | |||
| 13 | 586 | ||||
| 14 |
Devoteam | Google Cloud Partnergcloud.devoteam.com
Provides innovative Google Cloud solutions across AI, IT modernization, security, and work transformation, with expertise in migrating users and assisting organizations. |
579 | |||
| 15 |
Nexpublicanexpublica.com
Develops innovative, secure software solutions for public, parapublic, and private sectors, supporting over 4,000 public and 1,200 private organizations. |
559 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 16 |
ChapsVisionchapsvision.com
French software company specializing in data intelligence and AI, providing industry-specific solutions for diverse sectors, supporting digital transformation globally. |
558 | |||
| 17 |
Paritelparitel.fr
Paritel, a telecom operator for small businesses, prioritizes performance and individual talent while fostering teamwork and career development for its 700 employees |
501 | |||
| 18 |
Hervé Schauer Consultants (HSC)hs2.fr
Provides information security consulting, audits, penetration tests, risk management, and training services to secure diverse infrastructures and systems. |
500 | |||
| 19 |
Equans Digitalequans-digital.com
Connects operational and information technology systems to structure infrastructure data, improving energy efficiency, asset availability, and security through cybersecurity and applied artificial intelligence. |
499 | |||
| 20 |
Thales Cybersecurity Servicesthalesgroup.com
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. |
495 | |||
| 21 | 463 | ||||
| 22 | 435 | ||||
| 23 |
Stormshieldstormshield.com
Provides certified cybersecurity solutions for critical infrastructure, sensitive data, and operational environments to ensure cyber-serenity for clients globally. |
433 | |||
| 24 | 424 | ||||
| 25 |
Devoteam | Cyber Trustdevoteam.com
Empowering clients to protect digital transformation by managing risks and deploying innovative cybersecurity solutions, ensuring resilience in the digital age |
374 | |||
| 26 |
ADENTISadentis.fr
High-tech consulting company developing software and embedded systems for digital TV, telecom, medical electronics, defense, and aeronautics. Research lab. |
362 | |||
| 27 |
Avanquestavanquestgroup.com
A leading software publisher offering PDF, Security, and Photo products, utilizing cutting edge technology to enhance user experience worldwide |
340 | |||
| 28 |
Cloud Templecloud-temple.com
Provides IT transformation, hosting, and outsourcing for critical business applications. Guides customers from conception to maintenance across various IT verticals, specializing in private cloud. |
310 | |||
| 29 |
NEXTEDIAnextedia.com
The Nextedia Group specializes in Cybersecurity, Cloud, Digital Workspace, and Customer Experience, providing expertise and solutions to large companies across various sectors |
305 | |||
| 30 |
EfficientIPefficientip.com
Offers network security and automation, specializing in DNS-DHCP-IPAM (DDI), ensuring reliable, agile, and secure IP infrastructure for business continuity and application access. |
269 | |||
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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 5,160
- Multinational companies in the Hauts-de-Seine department 1,231
- IT services companies in the Hauts-de-Seine department 737
- IT Services and IT Consulting companies in the Hauts-de-Seine department 706
- Professional services firms in the Hauts-de-Seine department 629
- Consulting firms in the Hauts-de-Seine department 563
- Companies with in-house R&D in the Hauts-de-Seine department 510
- SaaS companies in the Hauts-de-Seine department 389
- Business Consulting and Services companies in the Hauts-de-Seine department 304
- Software Development companies in the Hauts-de-Seine department 301
- Retail chains in the Hauts-de-Seine department 292
- Manufacturers in the Hauts-de-Seine department 285
- Advertising Services companies in the Hauts-de-Seine department 281
- Marketing and communications agencies in the Hauts-de-Seine department 235
- Subscription businesses in the Hauts-de-Seine department 228
- Hardware manufacturers in the Hauts-de-Seine department 199
- Financial services firms in the Hauts-de-Seine department 198
- Companies with a mobile app in the Hauts-de-Seine department 189
- Critical infrastructure operators in the Hauts-de-Seine department 169
- AI companies in the Hauts-de-Seine department 159
- Education providers in the Hauts-de-Seine department 159
- Distributors and wholesalers in the Hauts-de-Seine department 154
- Recruitment and staffing agencies in the Hauts-de-Seine department 152
- Energy companies in the Hauts-de-Seine department 144
The same list elsewhere in France
- Cybersecurity companies in France 958
- Cybersecurity companies in Île-de-France 525
- Cybersecurity companies in Auvergne-Rhône-Alpes 91
- Cybersecurity companies in Occitanie 49
- Cybersecurity companies in Provence-Alpes-Côte d'Azur 48
- Cybersecurity companies in the Rhône department 48
- Cybersecurity companies in Hauts-de-France 44
- Cybersecurity companies in Grand Est 40
- Cybersecurity companies in Brittany 37
- Cybersecurity companies in the Bouches-du-Rhône department 36
- Cybersecurity companies in Nouvelle-Aquitaine 35
- Cybersecurity companies in the Nord department 30
- Cybersecurity companies in Pays de la Loire 28
- Cybersecurity companies in the Haute-Garonne department 27
- Cybersecurity companies in the Ille-et-Vilaine department 25
- Cybersecurity companies in the Yvelines department 25
- Cybersecurity companies in Paris 290