This selection of large critical infrastructure operators in Yvelines highlights significant employers in construction, environmental services, and public administration. Companies like Eiffage, with 7684 employees, and Bouygues Energies & Services, with 5960 employees, are prominent in building and maintaining essential infrastructure. Other key players include Banque Populaire Val de France in banking, SDIS 78 for fire and rescue, and ENSIO in telecommunications.
The data shows a strong presence of public and semi-public entities, alongside large private groups. A notable cluster of headquarters is found in Versailles, home to SDIS 78, Service d’infrastructure de la Défense, and CPAM des Yvelines, indicating a concentration of administrative and public service functions in the historic city.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
Eiffageeiffage.com
Join a close-knit company valuing teamwork, innovation, and individuality to build a human-sized future, welcoming diverse talents to thrive |
7,684 | |||
| 2 |
Bouygues Energies & Servicesbouygues-es.fr
Bouygues Energies & Services is a key player in energy and digital transition, focusing on sustainable solutions and workforce development |
5,960 | |||
| 3 |
Banque Populaire Val de Francebanquepopulaire.fr
This cooperative provides banking and insurance services, helping 550,000 clients and 132,700 members realize their personal and professional life projects. |
1,524 | |||
| 4 | 1,061 | ||||
| 5 | 964 | ||||
| 6 |
Eiffage Raileiffagerail.com
Specializes in rail infrastructure construction, maintenance, and modernization, providing comprehensive solutions for railway networks and urban transit systems. |
938 | |||
| 7 | 937 | ||||
| 8 |
Service d’infrastructure de la Défensedefense.gouv.fr
Manages, builds, and maintains the French Ministry of Armed Forces' real estate, ensuring infrastructure support and energy control for military operations domestically and abroad. |
850 | |||
| 9 |
Credit Agricole Payment Servicesca-payment-services.com
Designing payment solutions for group entities, processing transactions, and developing innovative, secure service offerings with leading market standards. |
736 | |||
| 10 |
Hôpital de Poissy-Saint-Germain-en-Layeghtyvelinesnord.fr
Public hospital in Yvelines, France, providing healthcare, education, and research across eight specialized care poles for all ages |
636 | |||
| 11 |
CPAM des Yvelinesameli.fr
A private organization serving the CNAM for public service, protecting over 15 million individuals by implementing healthcare policies locally in Yvelines |
480 | |||
| 12 |
Stellantis Financial Services UK, Germany and Austriastellantisfinancialservices.com
Provides vehicle finance solutions for brands within the Stellantis Group. Additionally, offers instant access and fixed-term deposit accounts in Germany. |
411 | |||
| 13 |
Centre Hospitalier de Plaisirch-plaisir.fr
Provides diverse, specialized hospital and outpatient care in South Yvelines, including radiology, MRI, and CT scans, focusing on gerontological, medico-social, and mental health. |
349 | |||
| 14 |
Centre hospitalier de Rambouilletch-rambouillet.fr
Provides diverse medical services including imaging, surgery, cardiology, dialysis, emergency care, and laboratory support for local population. |
345 | |||
| 15 |
Eiffage Concessionseiffageconcessions.com
The company specializes in developing sustainable infrastructure projects, focusing on transport, renewable energy, urban facilities, and quality of life improvement for communities |
338 | |||
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 |
Hôpital de Mantes-la-Jolieghtyvelinesnord.fr
Provides comprehensive, specialized hospital care, day hospital and outpatient surgery, accommodation beds, and various specialized consultations, as part of a public hospital group. |
253 | |||
| 17 |
HOPITAL PRIVE DE L'OUEST PARISIENhopital-prive-de-l-ouest-parisien-trappes.ramsaysante.fr
Multidisciplinary hospital providing high-quality medical-surgical care, established as the largest private Medicine Surgery Obstetrics (MCO) facility in Yvelines. |
202 | |||
| 18 | 198 | ||||
| 19 |
HOPITAL LE VESINEThopital-levesinet.fr
Specializing in follow-up care and rehabilitation services to support patients in their recovery and improve their overall well-being |
187 | |||
| 20 |
Hôpital de Meulan - Les Mureauxghtyvelinesnord.fr
Provides hospital care, day care, and consultations in various specialties, part of the Yvelines Nord hospital group. |
186 | |||
| 21 |
Les Sentinelles du Raillessentinellesdurail.fr
Established in 2014, a railway construction safety company with ISO 9001 and OHSAS 18001 certification, growing steadily with 190 operators, focusing on excellence, quality, and agility Offering various services for railway projects |
126 | |||
| 22 |
Colas Rail Infra Servicescolasrail.com
Ensuring safety on railway construction sites through human announcements, portable radio announcement devices, insulation devices, and managing work trains on closed lines. |
125 | |||
| 23 |
HOPITAL PRIVE DE VERSAILLEShopital-prive-de-versailles.ramsaysante.fr
A hospital and health care facility located in Versailles, France, providing medical services to patients in the ??le-de-France region |
93 | |||
| 24 |
CA-SILCA
IT production services for Groupe Crédit Agricole, including infrastructure management, cloud solutions, big data, SOC operations, and user services |
83 | |||
| 25 |
CASGBS - Communauté d'agglomération Saint Germain Boucles de Seinesaintgermainbouclesdeseine.fr
Join a dynamic intercommunal organization near Paris, dedicated to innovation in active mobility, environment, economic development, and more for the benefit of its diverse population |
78 | |||
| 26 |
Communauté d'agglomération Rambouillet Territoiresrt78.fr
Management of community space, economic growth, infrastructure, environment, culture, sports, generational actions, sanitation, and sustainable development across 36 communes. |
76 | |||
| 27 |
Sitrevasitreva.fr
A syndicate managing waste treatment and disposal for its members in France, operating waste collection services and recycling centers |
51 | |||
| 28 |
Clinique Saint-Germain - Vivalto Santécliniquesaintgermain.vivalto-sante.com
Operates as a multidisciplinary health facility in Saint-Germain-en-Laye, part of the third-largest national private hospitalization group. |
49 | |||
| 29 |
Centre Cardiologique d’Evecquemont - Vivalto Santécardiologie-evecquemont.fr
A healthcare center specializing in cardiovascular care, geriatrics, sleep disorder diagnostics Affiliated with Vivalto Santé group, serving 5,500 patients annually |
48 | |||
| 30 |
Centre Hospitalier de la Mauldrechmauldre.fr
Medical practice company in Îledefrance, France, focused on providing healthcare services at 23 Rue Saint Louis, Jouars Pontchartrain |
47 | |||
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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.
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- Government Administration companies in the Yvelines department 51
- Construction companies in the Yvelines department 50
- Automotive manufacturers and suppliers in the Yvelines department 49
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The same list elsewhere in France
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- Critical infrastructure operators in Bourgogne-Franche-Comté 76
- Critical infrastructure operators in the Haute-Garonne department 64
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- Critical infrastructure operators in the Loire-Atlantique department 59
- Critical infrastructure operators in the Hérault department 57
- Critical infrastructure operators in the Seine-Saint-Denis department 53
- Critical infrastructure operators in the Seine-Maritime department 46
- Critical infrastructure operators in Paris 331