# 30 leading IT services companies in the Hauts-de-Seine department

Tamtam tracks 737 IT services companies headquartered in the Hauts-de-Seine department. This list ranks the 30 largest by number of employees on LinkedIn, led by Orange, ALTEN and VINCI Energies. Their median headcount is 2,968. Half of them were founded in 1989 or later. The most common headquarters are Boulogne-Billancourt (7), Nanterre (6) and Neuilly-sur-Seine (4).

The Hauts-de-Seine department is home to a concentration of large IT services and consulting firms. These companies, many of which are well-established, offer a range of services from telecommunications to digital transformation. Notable examples include Orange, a global telecommunications operator; ALTEN, providing engineering and IT services; VINCI Energies, which implements multi-technical solutions for environmental transition; and Devoteam, an AI-driven tech consulting firm.

A significant pattern among these companies is their focus on digital transformation and technological solutions across various industries. Many are headquartered in a few key cities within the department, such as Boulogne-Billancourt, Nanterre, and Neuilly-sur-Seine.

🇫🇷 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 | [ALTEN](https://www.tamtam.ai/c/alten) (alten.com)<br>Provides engineering and IT services, supporting businesses in technological and sustainable transformation across various industries with high-level consultant-engineers. | Engineering Services | 🇫🇷 Boulogne-Billancourt | 38,710 | 1988 |
| 3 | [VINCI Energies](https://www.tamtam.ai/c/vinci-energies) (vinci-energies.com)<br>Contributes to environmental transition by implementing customized multi-technical solutions from design to maintenance, enhancing infrastructure reliability, efficiency, and sustainability for energy and digital sectors. | IT Services and IT Consulting | 🇫🇷 Nanterre | 25,848 |  |
| 4 | [Altran](https://www.tamtam.ai/c/altran) (capgemini-engineering.com)<br>Altran, now Capgemini Engineering, offers engineering services Follow them on LinkedIn for updates and insights | IT Services and IT Consulting | 🇫🇷 Neuilly-sur-Seine | 11,652 |  |
| 5 | [Devoteam](https://www.tamtam.ai/c/devoteam) (devoteam.com)<br>AI-driven tech consulting firm specializing in cloud platforms, cyber, data, and sustainability, guiding businesses through sustainable digital transformation to deliver value. | Business Consulting and Services | 🇫🇷 Levallois-Perret | 10,274 |  |
| 6 | [Econocom](https://www.tamtam.ai/c/econocom) (econocom.com)<br>Supplies, finances, and provides managed services for workplace, audiovisual, and infrastructures, supporting businesses in their digital transformation with equipment and support. | IT Services and IT Consulting | 🇫🇷 Puteaux | 7,123 | 1973 |
| 7 | [Actemium](https://www.tamtam.ai/c/actemium) (actemium.com)<br>Delivering bespoke solutions and services globally, combining local business unit expertise to create value throughout the industrial life cycle for a sustainable world. | Automation Machinery Manufacturing | 🇫🇷 Nanterre | 6,718 |  |
| 8 | [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 |
| 9 | [Vulcain Engineering Group](https://www.tamtam.ai/c/vulcain-engineering-group) (vulcain-eng.com)<br>Provides engineering consulting and project solutions for energy and environmental sectors, delivering technical assistance, expertise, and project management globally. | Business Consulting and Services | 🇫🇷 Neuilly-sur-Seine | 5,234 | 2005 |
| 10 | [OPEN](https://www.tamtam.ai/c/open-levallois-perret) (open.global)<br>Supports large companies and public organizations in digital transformation, focusing on technological performance, sovereignty, digital sobriety, and scaling innovations with advanced solutions. | IT Services and IT Consulting | 🇫🇷 Levallois-Perret | 4,705 | 1989 |
| 11 | [Axians](https://www.tamtam.ai/c/axians) (axians.com)<br>A technology company supporting digital transformation by providing ICT solutions in cybersecurity, telecommunication, data analytics, cloud services, and more | IT Services and IT Consulting | 🇫🇷 Nanterre | 4,186 |  |
| 12 | [Cegedim](https://www.tamtam.ai/c/cegedim) (cegedim.com)<br>Technology and services for digital data flow management in healthcare ecosystems and B2B, plus business software publishing for healthcare and insurance professionals. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 4,103 | 1969 |
| 13 | [Scalian](https://www.tamtam.ai/c/scalian) (scalian.com)<br>A global company founded in 1989 with 3 business lines focusing on Digital Transformation, Digital Systems, and Operations Performance across various countries | Business Consulting and Services | 🇫🇷 Neuilly-sur-Seine | 4,098 | 1989 |
| 14 | [VISEO](https://www.tamtam.ai/c/viseo) (viseo.com)<br>Assists clients globally with digital and business transformation using advanced technology and industry expertise for productivity, innovation, and competitiveness. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 3,016 | 1999 |
| 15 | [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 |
| 16 | [VINCI Energies en France](https://www.tamtam.ai/c/vinci-energies-en-france)<br>Accelerating environmental transition in France by focusing on energy and digital transformations for factories, buildings, cities, and energy/transport infrastructure with innovative solutions | Environmental Services | 🇫🇷 Nanterre | 2,953 |  |
| 17 | [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 |
| 18 | [SQLI](https://www.tamtam.ai/c/sqli) (sqli.com)<br>Leading European group for customer experience and digital transformation services. Empowering international brands with digital innovation, combining technology, methodologies, and AI for business growth. | IT Services and IT Consulting | 🇫🇷 Levallois-Perret | 2,854 | 1990 |
| 19 | [Sogetrel](https://www.tamtam.ai/c/sogetrel) (sogetrel.fr)<br>A leader in digital transformation, specializing in digital infrastructure services and connected devices to enhance citizens' lives, business performance, and sustainable development | Telecommunications | 🇫🇷 Issy-les-Moulineaux | 2,581 | 1985 |
| 20 | [Apside](https://www.tamtam.ai/c/apside) (apside.com)<br>Provides consulting, engineering in Information Systems, Technical and Scientific Computing, Automotive and Financial Engineering, for large French and European groups. | IT Services and IT Consulting | 🇫🇷 Boulogne-Billancourt | 2,300 | 1976 |
| 21 | [HELPLINE](https://www.tamtam.ai/c/helpline) (helpline.fr)<br>Specialized in user support outsourcing, AI-enhanced employee experience, and IT asset management. Supports IT departments and offers seamless employee experience. | IT Services and IT Consulting | 🇫🇷 Nanterre | 2,115 | 1994 |
| 22 | [agap2](https://www.tamtam.ai/c/agap2) (agap2.com)<br>Global consulting firm specializing in industries and information systems, creating value for customers and consultants through innovation and extensive technical know-how. | Business Consulting and Services | 🇫🇷 Boulogne-Billancourt | 2,075 | 2005 |
| 23 | [Infotel](https://www.tamtam.ai/c/infotel) (infotel.com)<br>Provides IT and digital transformation consulting for large enterprises, focusing on strategic design, technological expertise, and agile development, from conception to implementation. | IT Services and IT Consulting | 🇫🇷 Neuilly-sur-Seine | 1,894 | 1979 |
| 24 | [Extia](https://www.tamtam.ai/c/extia) (extia-group.com)<br>Offers IT consulting services across various sectors, focusing on employee well-being to drive project success and client performance with a collaborative approach. | IT Services and IT Consulting | 🇫🇷 Sèvres | 1,881 | 2007 |
| 25 | [Sopra HR Software](https://www.tamtam.ai/c/sopra-hr-software) (soprahr.com)<br>Provides payroll, HR management, and digitalization solutions for medium to large organizations, leveraging digital and AI for HR transformation in local and international contexts. | Human Resources Services | 🇫🇷 Courbevoie | 1,880 | 2015 |
| 26 | [Davidson consulting](https://www.tamtam.ai/c/davidson-consulting) (davidson.fr)<br>A management consulting and technology company with over 2,000 employees, expanding internationally with a focus on employee well-being and creativity | Business Consulting and Services | 🇫🇷 Boulogne-Billancourt | 1,843 | 2005 |
| 27 | [Sofrecom](https://www.tamtam.ai/c/sofrecom) (sofrecom.com)<br>Advises, guides, and supports telecommunications players' digital transformation and green transition, offering business, network, and IT consulting for improved operational performance. | IT Services and IT Consulting | 🇫🇷 Châtillon | 1,469 | 1966 |
| 28 | [Niji](https://www.tamtam.ai/c/niji) (niji.fr)<br>Provides consulting, design, and technology implementation for digital transformation in businesses and public organizations, including Salesforce integration and cybersecurity. | IT Services and IT Consulting | 🇫🇷 Issy-les-Moulineaux | 1,460 | 2001 |
| 29 | [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 |
| 30 | [IGA](https://www.tamtam.ai/c/iga) (iga.fr)<br>Develops software components, creates custom solutions, implements installations, and provides specific services like hosting and accounting outsourcing for insurance, travel, and trade. | Software Development | 🇫🇷 Malakoff | 1,358 | 1985 |

## 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)
- [IT Services and IT Consulting companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/it-services-and-it-consulting-companies-hauts-de-seine) (706)
- [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)
- [Advertising Services companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/advertising-services-companies-hauts-de-seine) (281)
- [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)
- [Cybersecurity companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/cybersecurity-companies-hauts-de-seine) (154)
- [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)
- [Energy companies in the Hauts-de-Seine department](https://www.tamtam.ai/l/energy-companies-hauts-de-seine) (144)

## The same list elsewhere in France

- [IT services companies in France](https://www.tamtam.ai/l/it-services-companies-france) (5,000)
- [IT services companies in Île-de-France](https://www.tamtam.ai/l/it-services-companies-ile-de-france) (2,624)
- [IT services companies in Auvergne-Rhône-Alpes](https://www.tamtam.ai/l/it-services-companies-auvergne-rhone-alpes) (519)
- [IT services companies in the Rhône department](https://www.tamtam.ai/l/it-services-companies-rhone) (286)
- [IT services companies in Occitanie](https://www.tamtam.ai/l/it-services-companies-occitanie) (280)
- [IT services companies in Provence-Alpes-Côte d'Azur](https://www.tamtam.ai/l/it-services-companies-provence-alpes-cote-dazur) (268)
- [IT services companies in Grand Est](https://www.tamtam.ai/l/it-services-companies-grand-est) (248)
- [IT services companies in Hauts-de-France](https://www.tamtam.ai/l/it-services-companies-hauts-de-france) (236)
- [IT services companies in Pays de la Loire](https://www.tamtam.ai/l/it-services-companies-pays-de-la-loire) (205)
- [IT services companies in Nouvelle-Aquitaine](https://www.tamtam.ai/l/it-services-companies-nouvelle-aquitaine) (194)
- [IT services companies in the Nord department](https://www.tamtam.ai/l/it-services-companies-nord) (170)
- [IT services companies in the Haute-Garonne department](https://www.tamtam.ai/l/it-services-companies-haute-garonne) (158)
- [IT services companies in the Bouches-du-Rhône department](https://www.tamtam.ai/l/it-services-companies-bouches-du-rhone) (155)
- [IT services companies in the Loire-Atlantique department](https://www.tamtam.ai/l/it-services-companies-loire-atlantique) (130)
- [IT services companies in the Yvelines department](https://www.tamtam.ai/l/it-services-companies-yvelines) (121)
- [IT services companies in Brittany](https://www.tamtam.ai/l/it-services-companies-brittany) (113)
- [IT services companies in the Val-de-Marne department](https://www.tamtam.ai/l/it-services-companies-val-de-marne) (101)
- [IT services companies in the Gironde department](https://www.tamtam.ai/l/it-services-companies-gironde) (99)
- [IT services companies in Paris](https://www.tamtam.ai/l/it-services-companies-paris) (1,386)
- [IT services companies in Lyon](https://www.tamtam.ai/l/it-services-companies-lyon) (171)
- [IT services companies in Boulogne-Billancourt](https://www.tamtam.ai/l/it-services-companies-boulogne-billancourt) (125)
- [IT services companies in Toulouse](https://www.tamtam.ai/l/it-services-companies-toulouse) (119)
- [IT services companies in Levallois-Perret](https://www.tamtam.ai/l/it-services-companies-levallois-perret) (94)
- [IT services companies in Neuilly-sur-Seine](https://www.tamtam.ai/l/it-services-companies-neuilly-sur-seine) (87)

---

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