These are critical infrastructure operators in the Seine-et-Marne department, mostly mid-sized firms. The companies listed include TSO, specializing in rail construction and maintenance, and Grand Hôpital de l'Est Francilien, an integrated hospital network. SDIS 77 - Sapeurs-pompiers de Seine-et-Marne focuses on fire prevention and emergency response, while CASDEN Banque Populaire is a cooperative bank for the public sector. CELESTE provides internet and connectivity solutions for businesses.
A clear pattern emerges with a strong presence of companies in the rail transportation sector, such as TSO, TSO CATENAIRES, and FVF - Sécurité Ferroviaire, all headquartered in Chelles. This indicates a significant concentration of expertise and operations related to railway infrastructure in that specific city.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 | 2,494 | ||||
| 2 |
Grand Hôpital de l'Est Francilienghef.fr
Integrated hospital network providing extensive medical and psychiatric care across multiple sites, serving the northern Seine-et-Marne population. |
904 | |||
| 3 |
SDIS 77 - Sapeurs-pompiers de Seine-et-Marnesdis77.fr
A public establishment in Seine-et-Marne focused on preventing, protecting, and fighting fires, as well as providing emergency response in the region |
862 | |||
| 4 |
CASDEN Banque Populairecasden.fr
The company is a cooperative bank serving the public sector, offering savings, loans, and insurance with a focus on social values and partnerships |
642 | |||
| 5 |
CELESTEceleste.fr
A national provider of internet access and connectivity solutions for businesses, offering innovative, high-availability, and eco-friendly services such as fiber optic connections and cloud hosting |
537 | |||
| 6 |
TSO CATENAIREStso.fr
Specializes in designing, installing, and maintaining electrification and power supply systems essential for sustainable railway infrastructure projects worldwide. |
403 | |||
| 7 |
Numericablenumericable.fr
Leading French cable operator offering modular TV, internet, phone, and mobile services to 98 million households, with extensive coverage and high-speed fiber options |
354 | |||
| 8 |
Centre hospitalier du Sud Seine-et-Marnech-sud-seine-et-marne.fr
Groups hospitals in Fontainebleau, Montereau-Fault-Yonne, and Nemours, resulting from a shared medical project to provide healthcare services in the region. |
332 | |||
| 9 |
Fondation Ellen Poidatzfondationpoidatz.com
Management of pediatric rehabilitation centers, support for disabled children and adults, adapted schooling, and research in healthcare innovation. |
329 | |||
| 10 |
HOPITAL FORCILLES - Fondation Cognacq-Jayhopital-forcilles.cognacq-jay.fr
The company provides rehabilitation for patients with chronic diseases, cancer treatment expertise, and medical consultations for locals in Seine-et-Marne |
278 | |||
| 11 |
Groupe Hospitalier Sud Ile-de-Franceghsif.fr
Leading public healthcare group in Southern Seine-et-Marne, France, comprised of hospitals, health facilities, and a shared direction with a gerontology establishment |
259 | |||
| 12 | 163 | ||||
| 13 |
FVF - Sécurité Ferroviairetso.fr
Since 2012, a company specializing in railway security works on maintenance, regeneration, and new line projects with a focus on safety for clients like SNCF |
148 | |||
| 14 |
TSO SIGNALISATIONtso.fr
The company offers a comprehensive range of railway signaling services including technical studies, civil engineering, signaling, telecommunications, rockfall detection, and railway safety |
105 | |||
| 15 |
ProCarsprocars.com
ProCars is a private and independent road passenger transport company in Île-de-France, offering various services including tourist transportation and event services |
100 | |||
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 |
Clinique Saint-Jean l'Ermitageclinique-saint-jean-ermitage.fr
A leading private clinic in Île-de-France with over 50 years of experience, offering specialized medical care in surgery, medicine, rehabilitation, imaging, and oncology |
95 | |||
| 17 |
CH Léon Binet - Provins
Diagnostic, treatment, prevention, and health education services, operating a hospital with 399 beds and 60 places, employing 900 professionals. |
67 | |||
| 18 |
HOPITAL PRIVE DE MARNE CHANTEREINEhopital-prive-marne-chantereine.ramsaysante.fr
A medical practice company located in Île-de-France, France, providing healthcare services at RUE MARIE CURIE in Brou Sur Chantereine |
65 | |||
| 19 |
Appliwaveappliwave.com
An operator Cloud and Telecom provider through a network of partners, offering innovative solutions for SMEs and midsize companies in France and Germany |
40 | |||
| 20 |
Communauté de Communes Brie des Rivières et Châteaux - CCBRC (77)briedesrivieresetchateaux.fr
Rural intercommunal group, 31 municipalities, 39,445 inhabitants. Historical and landscape heritage, castles and rivers. South Seine-et-Marne. |
39 | |||
| 21 |
MÉDECINE INTENSIVE-RÉANIMATION GHSIF MELUNghsif.fr
The company provides intensive care services for critically ill patients, offering advanced diagnostic and treatment techniques for various organ failures |
36 | |||
| 22 | 35 | ||||
| 23 |
HAD de la région de Melunhadmelun.fr
Established in May 2016, the company provides comprehensive healthcare services to patients at home in the Melun region through a non-profit private healthcare partnership |
34 | |||
| 24 |
CLINIQUE DE MONTEVRAINclinique-montevrain.ramsaysante.fr
A medical practice company located in Montevrain, France, offering healthcare services at 15 RTE DE PROVINS in Îledefrance |
30 | |||
| 25 |
PSP GROUPEpsp-groupe.fr
Specialized in partial and full load transport, express and courier services across France and Europe, including import, export, and logistics. |
29 | |||
| 26 |
Mainfreight Francemainfreight.com
Specialist in palletized groupage and full load transport across France and Europe, including hazardous goods with real-time tracking. |
25 | |||
| 27 |
SIETREMsietrem.fr
A mixed syndicate managing waste collection, treatment, and valorization for 31 municipalities, also running a waste prevention program, led by Christian ROBACHE |
25 | |||
| 28 |
MEDIA FRETmediafret.com
Specialized transport and logistics services with extensive experience, ensuring secure, cost-effective freight delivery across France and internationally. |
22 | |||
| 29 |
Keolis Portes et Val de Brie
A global public transport operator, leading in automatic metro and tramway systems, as well as healthcare transport and parking services Serving 300 authorities worldwide |
20 | |||
| 30 |
Keolis Roissy Pays de France Estiledefrance-mobilites.fr
Global public transport operator providing services in 16 countries on 4 continents, specializing in automated metros, trams, medical transport, and parking solutions Serving 3 billion passengers annually |
15 | |||
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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 Seine-et-Marne department
- The largest companies in the Seine-et-Marne department 947
- Multinational companies in the Seine-et-Marne department 139
- Companies with in-house R&D in the Seine-et-Marne department 104
- Manufacturers in the Seine-et-Marne department 100
- Hardware manufacturers in the Seine-et-Marne department 84
- Distributors and wholesalers in the Seine-et-Marne department 82
- Retail chains in the Seine-et-Marne department 68
- Construction companies in the Seine-et-Marne department 57
- Family-owned companies in the Seine-et-Marne department 49
- Public sector organisations in the Seine-et-Marne department 49
- Professional services firms in the Seine-et-Marne department 41
- Government Administration companies in the Seine-et-Marne department 39
- Industrial Machinery Manufacturing companies in the Seine-et-Marne department 34
- Wholesale companies in the Seine-et-Marne department 34
- Retail companies in the Seine-et-Marne department 33
- Education providers in the Seine-et-Marne department 31
- IT Services and IT Consulting companies in the Seine-et-Marne department 31
- IT services companies in the Seine-et-Marne department 29
- Contract manufacturers in the Seine-et-Marne department 26
- Healthcare providers in the Seine-et-Marne department 26
- Higher Education companies in the Seine-et-Marne department 25
The same list elsewhere in France
- Critical infrastructure operators in France 2,721
- Critical infrastructure operators in Île-de-France 780
- Critical infrastructure operators in Auvergne-Rhône-Alpes 299
- Critical infrastructure operators in Grand Est 257
- Critical infrastructure operators in Occitanie 216
- Critical infrastructure operators in Nouvelle-Aquitaine 209
- Critical infrastructure operators in Provence-Alpes-Côte d'Azur 200
- Critical infrastructure operators in Hauts-de-France 174
- Critical infrastructure operators in the Hauts-de-Seine department 169
- Critical infrastructure operators in Pays de la Loire 127
- Critical infrastructure operators in Brittany 120
- Critical infrastructure operators in Normandy 103
- Critical infrastructure operators in the Bouches-du-Rhône department 98
- Critical infrastructure operators in the Rhône department 94
- Critical infrastructure operators in Centre-Val de Loire 87
- Critical infrastructure operators in the Nord department 87
- Critical infrastructure operators in Bourgogne-Franche-Comté 76
- Critical infrastructure operators in the Haute-Garonne department 64
- Critical infrastructure operators in the Gironde department 63
- 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