# The 30 largest public sector organisations in the Seine-Saint-Denis department

Tamtam tracks 91 public sector organisations headquartered in the Seine-Saint-Denis department. This list ranks the 30 largest by number of employees on LinkedIn, led by SNCF Réseau, AFPA and SNCF Voyageurs. Their median headcount is 823. Half of them were founded in 1970 or later. The most common headquarters are Saint-Denis (12), Montreuil (10) and Bobigny (2).

These public sector organisations in Seine-Saint-Denis are primarily large entities, many of them national in scope. They represent a mix of government administration, higher education, and public transportation. For example, SNCF Réseau manages national railway infrastructure, AFPA is a leading adult professional training organization, and ACOSS supports employers and entrepreneurs.

The data shows a strong concentration of headquarters in Saint-Denis and Montreuil. Several universities, such as Université Sorbonne Paris Nord and Université Paris 8, are also prominent. The presence of entities like Société des grands projets highlights ongoing development in urban transit services.

🇫🇷 Seine-Saint-Denis · 30 companies · Updated Nov 12, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [SNCF Réseau](https://www.tamtam.ai/c/sncf-reseau) (sncf-reseau.fr)<br>public entity managing national railway infrastructure, unifying previous services, ensuring clear governance, and coordinating with railway operator SNCF Mobilités. | Rail Transportation | 🇫🇷 Saint-Denis | 23,115 | 2015 |
| 2 | [AFPA](https://www.tamtam.ai/c/afpa) (afpa.fr)<br>Leading adult professional training organization in France, offering a wide range of job-focused courses to help individuals gain employment and assist companies in workforce development | Professional Training and Coaching | 🇫🇷 Montreuil | 19,244 | 1946 |
| 3 | [SNCF Voyageurs](https://www.tamtam.ai/c/sncf-voyageurs) (sncf-voyageurs.com)<br>SNCF Voyageurs is a subsidiary of the SNCF Group responsible for passenger transportation on the French national railway network | Rail Transportation | 🇫🇷 Saint-Denis | 18,564 | 2020 |
| 4 | [Conseil départemental de la Seine-Saint-Denis](https://www.tamtam.ai/c/conseil-departemental-de-la-seine-saint-denis) (seinesaintdenis.fr)<br>The company works to create opportunities for local economic development, ensuring that residents benefit from job initiatives and new actions | Government Administration | 🇫🇷 Bobigny | 3,255 |  |
| 5 | [ACOSS](https://www.tamtam.ai/c/acoss) (linkedin.com)<br>A national organization supports employers and entrepreneurs by advising, informing, and streamlining services, ensuring social protection financing, and promoting responsibility, solidarity, and equity | Government Administration | 🇫🇷 Montreuil | 3,000 |  |
| 6 | [Agence Régionale de Santé Ile-de-France](https://www.tamtam.ai/c/agence-regionale-de-sante-ile-de-france) (linktr.ee)<br>Implements regional health policy, covering prevention, care, and medico-social support, developed in consultation with professionals and users for efficiency and transparency. | Government Administration | 🇫🇷 Saint-Denis | 2,332 | 2010 |
| 7 | [Université Sorbonne Paris Nord](https://www.tamtam.ai/c/universite-sorbonne-paris-nord) (univ-spn.fr)<br>A multidisciplinary university located in the northern region of Île-de-France, with campuses in Villetaneuse, Saint-Denis, La Plaine Saint-Denis, Bobigny, and Argenteuil | Higher Education | 🇫🇷 Villetaneuse | 2,033 | 1970 |
| 8 | [Université Paris 8](https://www.tamtam.ai/c/universite-paris-8) (univ-paris8.fr)<br>A leading university in Paris, specializing in Arts, Literature, Social Sciences, and Humanities, providing students with tools to understand and engage with the contemporary world | Higher Education | 🇫🇷 Saint-Denis | 1,594 | 1969 |
| 9 | [Urssaf Caisse nationale](https://www.tamtam.ai/c/urssaf-caisse-nationale) (urssaf.org)<br>Collects contributions from employers, self-employed, and employees to fund social benefits like healthcare, hospitals, and public transport, supporting economic and social development. | Government Administration | 🇫🇷 Montreuil | 1,470 | 1960 |
| 10 | [Société des grands projets](https://www.tamtam.ai/c/societe-des-grands-projets) (societedesgrandsprojets.fr)<br>Development and management of decarbonized transport projects including new metro lines and regional express services to improve daily mobility. | Urban Transit Services | 🇫🇷 Saint-Denis | 1,367 |  |
| 11 | [Université Paris 8 Vincennes-Saint-Denis](https://www.tamtam.ai/c/universite-paris-8-vincennes-saint-denis) (univ-paris8.fr)<br>Higher education institution specializing in cultural sciences, hosting over 21,000 students, numerous research teams, and doctoral schools in Paris. | Higher Education | 🇫🇷 Saint-Denis | 1,177 | 1969 |
| 12 | [Urssaf Ile-de-France](https://www.tamtam.ai/c/urssaf-ile-de-france) (lasecurecrute.fr)<br>Collection and redistribution of social security contributions ensuring workers' social protection and supporting entrepreneurs with compliance and service. | Government Administration | 🇫🇷 Montreuil | 1,142 |  |
| 13 | [Université Paris 13](https://www.tamtam.ai/c/universite-paris-13) (univ-spn.fr)<br>Higher education institution offering diverse academic programs across four main campuses located in northern Île-de-France region. | Higher Education | 🇫🇷 Villetaneuse | 1,049 | 1970 |
| 14 | [Plaine Commune](https://www.tamtam.ai/c/plaine-commune) (plainecommune.fr)<br>A territory in the Greater Paris region undergoing significant transformation, known for culture, creativity, and hosting events like Paris 2024 Keep updated on social media | Government Administration | 🇫🇷 Saint-Denis | 1,017 | 2000 |
| 15 | [Ville de Montreuil](https://www.tamtam.ai/c/ville-de-montreuil) (montreuil.fr)<br>Local government providing public services and employment opportunities for residents in a densely populated urban area in Île-de-France. | Government Administration | 🇫🇷 Montreuil | 823 |  |
| 16 | [Ville de Saint-Denis](https://www.tamtam.ai/c/ville-de-saint-denis) (ville-saint-denis.fr)<br>Local government providing public services, supporting daily life and personal projects for approximately 115,000 residents in Saint-Denis. | Government Administration | 🇫🇷 Saint-Denis | 666 |  |
| 17 | [FranceAgriMer](https://www.tamtam.ai/c/franceagrimer) (franceagrimer.fr)<br>A national establishment under the French Ministry for Agriculture, providing economic expertise, market monitoring, and strategic support for the agriculture and sea sectors | Government Administration | 🇫🇷 Montreuil | 636 | 2009 |
| 18 | [SNCF Voyageurs Matériel](https://www.tamtam.ai/c/sncf-voyageurs-materiel) (sncf-voyageurs.com)<br>Manages maintenance for nearly 17,000 rolling stock units. Provides high-level industrial performance, ensuring safety, quality, and technical expertise for internal and external clients. | Rail Transportation | 🇫🇷 Saint-Denis | 606 |  |
| 19 | [Cour nationale du droit d'asile (CNDA)](https://www.tamtam.ai/c/cour-nationale-du-droit-d-asile-cnda) (cnda.fr)<br>Specialized administrative court in France responsible for reviewing asylum decisions and appeals against the decisions of the French Office for Refugees and Stateless Persons | Government Administration | 🇫🇷 Montreuil | 549 |  |
| 20 | [Economat des armées](https://www.tamtam.ai/c/economat-des-armees) (economat-armees.com)<br>Central purchasing and service provider supporting defense administrative units with food supply, collective catering, general goods, transport, and camp management. | Defense and Space Manufacturing | 🇫🇷 Pantin | 521 | 1959 |
| 21 | [UCANSS](https://www.tamtam.ai/c/ucanss) (ucanss.fr)<br>It is an employer federation for Social Security, managing social dialogue, offering HR, purchasing, and real estate services, and promoting innovation and efficiency for its clients. | Government Administration | 🇫🇷 Montreuil | 511 | 1970 |
| 22 | [Grand Paris Express](https://www.tamtam.ai/c/grand-paris-express) (grandparisexpress.fr)<br>Public organization creating the new Grand Paris automated metro, responsible for designing, developing, and building the network's infrastructure and stations | Urban Transit Services | 🇫🇷 Saint-Denis | 454 | 2011 |
| 23 | [AFPAR](https://www.tamtam.ai/c/afpar) (afpar.re)<br>A Public Local Company in Réunion specializing in professional training, career reconversion, and enhancing employability of job seekers for 60 years | Technical and Vocational Training | 🇫🇷 Saint-Denis | 432 | 1963 |
| 24 | [UGECAM Ile-de-France](https://www.tamtam.ai/c/ugecam-ile-de-france) (groupe-ugecam.fr)<br>Non-profit organization providing comprehensive health and social care services, supporting rehabilitation and reintegration for individuals with disabilities across various age groups and needs. | Hospitals and Health Care | 🇫🇷 Montreuil | 419 | 2000 |
| 25 | [CENTRE HOSPITALIER DE MONTREUIL HOPITAL ANDRE GREGOIRE](https://www.tamtam.ai/c/centre-hospitalier-de-montreuil-hopital-andre-gregoire) (ght-gpne.fr)<br>Medical practice company based in Montreuil, France, providing a range of healthcare services at Hôpital André Grégoire | Medical Practices | 🇫🇷 Montreuil | 388 |  |
| 26 | [Centre Interdépartemental de Gestion de la petite couronne d'Ile de France](https://www.tamtam.ai/c/centre-interdepartemental-de-gestion-de-la-petite-couronne-d-ile-de-france) (cig929394.fr)<br>Provides human resources management services to local authorities and public establishments. Offers HR advice, services, and expert support in employment, health, and statutory matters. | Human Resources Services | 🇫🇷 Pantin | 337 | 1984 |
| 27 | [Mairie du Blanc-Mesnil](https://www.tamtam.ai/c/mairie-du-blanc-mesnil) (blancmesnil.fr)<br>Local government administration serving over 57,300 residents in Seine-Saint-Denis, providing municipal services and community information. | Government Administration | 🇫🇷 Le Blanc-Mesnil | 318 |  |
| 28 | [Seine-Saint-Denis habitat](https://www.tamtam.ai/c/seine-saint-denis-habitat) (seinesaintdenishabitat.fr)<br>A leading social housing provider in Seine-Saint-Denis, managing over 33,000 rental units in 30 municipalities in the department | Real Estate | 🇫🇷 Bobigny | 306 | 1970 |
| 29 | [GHT Grand Paris Nord-Est](https://www.tamtam.ai/c/ght-grand-paris-nord-est) (ght-gpne.fr)<br>Three hospitals in Seine-Saint-Denis providing specialized, teaching, and research healthcare services with over 6000 professionals ensuring coordinated, quality patient care. | Hospitals and Health Care | 🇫🇷 Montfermeil | 297 | 2016 |
| 30 | [Centre Hospitalier de Saint-Denis](https://www.tamtam.ai/c/centre-hospitalier-de-saint-denis) (ch-stdenis.fr)<br>Public hospital offering medical care without discrimination, with a focus on multicultural patient care Provides various medical specialties, including emergency services and perinatal care | Hospitals and Health Care | 🇫🇷 Saint-Denis | 293 |  |

## 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 12, 2026.

## More company lists in the Seine-Saint-Denis department

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- [SaaS companies in the Seine-Saint-Denis department](https://www.tamtam.ai/l/saas-companies-seine-saint-denis) (37)
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## The same list elsewhere in France

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- [Public sector organisations in Grand Est](https://www.tamtam.ai/l/public-sector-organisations-grand-est) (427)
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- [Public sector organisations in Occitanie](https://www.tamtam.ai/l/public-sector-organisations-occitanie) (317)
- [Public sector organisations in Nouvelle-Aquitaine](https://www.tamtam.ai/l/public-sector-organisations-nouvelle-aquitaine) (310)
- [Public sector organisations in Hauts-de-France](https://www.tamtam.ai/l/public-sector-organisations-hauts-de-france) (261)
- [Public sector organisations in Pays de la Loire](https://www.tamtam.ai/l/public-sector-organisations-pays-de-la-loire) (185)
- [Public sector organisations in the Bouches-du-Rhône department](https://www.tamtam.ai/l/public-sector-organisations-bouches-du-rhone) (183)
- [Public sector organisations in Normandy](https://www.tamtam.ai/l/public-sector-organisations-normandy) (166)
- [Public sector organisations in Brittany](https://www.tamtam.ai/l/public-sector-organisations-brittany) (165)
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- [Public sector organisations in Bourgogne-Franche-Comté](https://www.tamtam.ai/l/public-sector-organisations-bourgogne-franche-comte) (130)
- [Public sector organisations in Centre-Val de Loire](https://www.tamtam.ai/l/public-sector-organisations-centre-val-de-loire) (121)
- [Public sector organisations in the Rhône department](https://www.tamtam.ai/l/public-sector-organisations-rhone) (120)
- [Public sector organisations in the Haute-Garonne department](https://www.tamtam.ai/l/public-sector-organisations-haute-garonne) (111)
- [Public sector organisations in the Gironde department](https://www.tamtam.ai/l/public-sector-organisations-gironde) (109)
- [Public sector organisations in the Hauts-de-Seine department](https://www.tamtam.ai/l/public-sector-organisations-hauts-de-seine) (96)
- [Public sector organisations in the Isère department](https://www.tamtam.ai/l/public-sector-organisations-isere) (80)
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- [Public sector organisations in Toulouse](https://www.tamtam.ai/l/public-sector-organisations-toulouse) (83)

## The same list elsewhere

- [Public sector organisations in the world](https://www.tamtam.ai/l/public-sector-organisations-in-the-world) (18,493)
- [Public sector organisations in Europe](https://www.tamtam.ai/l/public-sector-organisations-in-europe) (8,568)

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Source: https://www.tamtam.ai/l/public-sector-organisations-seine-saint-denis