# The 30 largest IT services companies in the Loire-Atlantique department

Tamtam tracks 130 IT services companies headquartered in the Loire-Atlantique department. This list ranks the 30 largest by number of employees on LinkedIn, led by Experis France, Catamania and U IRIS devient U TECH. Their median headcount is 156. Half of them were founded in 2000 or later. The most common headquarters are Saint-Herblain (10), Nantes (9) and La Chapelle-sur-Erdre (4).

These large IT services companies in Loire-Atlantique provide a range of digital transformation, consulting, and software development services. Companies like Experis France support DSI with innovative digital transformation projects, while Catamania offers digital transformation services, consulting, and software publishing. Groupe Sigma aims to enhance performance through digital impact, and ASI® focuses on a responsible digital world. U IRIS devient U TECH manages the IT system for Groupement U, and Conserto provides IT consulting across cloud, digital, and embedded domains.

The companies listed here are primarily established mid-sized to large firms, with a concentration of headquarters in Saint-Herblain. Many were founded in the late 1990s and early 2000s, indicating a mature and well-developed IT sector in the region, focusing on diverse technical expertise and comprehensive digital solutions for various sectors.

🇫🇷 Loire-Atlantique · 30 companies · Updated Nov 12, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Experis France](https://www.tamtam.ai/c/experis-france) (experisfrance.fr)<br>Supports DSI with innovative digital transformation projects, providing IT services and talent solutions to enhance organizational performance, addressing specific needs. | IT Services and IT Consulting | 🇫🇷 Nantes | 2,207 |  |
| 2 | [Catamania](https://www.tamtam.ai/c/catamania) (catamania.com)<br>Provides digital transformation services, consulting, software publishing, and information system architecture for banking, insurance, and retail sectors across international agencies using diverse technical expertise. | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 797 | 1999 |
| 3 | [U IRIS devient U TECH](https://www.tamtam.ai/c/u-iris-devient-u-tech) (u-emploi.com)<br>Management and innovation of the entire Groupement U IT system, supporting retail, supply chain, and digital transformation projects. | Software Development | 🇫🇷 Carquefou | 637 | 2011 |
| 4 | [Groupe Sigma](https://www.tamtam.ai/c/groupe-sigma-la-chapelle-sur-erdre) (sigma.fr)<br>The company aims to enhance performance through digital impact, innovate eco-friendly solutions, and build digital ecosystems with expert dialogue | IT Services and IT Consulting | 🇫🇷 La Chapelle-sur-Erdre | 607 | 1972 |
| 5 | [ASI ®](https://www.tamtam.ai/c/asi) (asi.fr)<br>Working towards a responsible digital world dedicated to serving humanity | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 590 | 1993 |
| 6 | [Conserto](https://www.tamtam.ai/c/conserto) (conserto.pro)<br>Offers IT consulting and expertise services across cloud, digital, and embedded domains through consulting, delivery centers, and labs models. | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 555 | 2013 |
| 7 | [4CAD Group](https://www.tamtam.ai/c/4cad-group) (4cadgroup.com)<br>The company offers PLM, ERP, and IoT tools to help organizations optimize their information systems for increased industrial efficiency | Software Development | 🇫🇷 Bouguenais | 463 | 2004 |
| 8 | [AIS](https://www.tamtam.ai/c/ais) (groupeais.fr)<br>AIS is a human-centric company providing expertise to clients since 1985, focusing on professional growth and fulfillment of its employees | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 289 | 1985 |
| 9 | [Younup](https://www.tamtam.ai/c/younup) (younup.fr)<br>This company offers IT services, supporting clients throughout the software lifecycle from requirements to production, focusing on web, DevOps, data, AI, agility, mobile, and cloud. | IT Services and IT Consulting | 🇫🇷 Nantes | 224 | 2019 |
| 10 | [GROUPE SYD](https://www.tamtam.ai/c/groupe-syd) (syd.fr)<br>Specializing in digital transformation, the company offers consultancy, project management, infrastructure services, Microsoft solutions integration, application development, and Microsoft expertise, emphasizing customer satisfaction and trust | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 190 | 1999 |
| 11 | [Dynamips](https://www.tamtam.ai/c/dynamips) (dynamips.com)<br>A pioneer in professional IT services, providing support to SMEs and Local Authorities across France Specializing in optimizing systems, data security, cloud solutions, and personalized IT services | Computer Networking Products | 🇫🇷 Saint-Herblain | 179 | 1992 |
| 12 | [ORINOX](https://www.tamtam.ai/c/orinox) (orinox.com)<br>Software consulting and plant design firm specializing in digitalization using AVEVA software suite for engineering, asset data visualization, resources management, simulation, and training | Business Consulting and Services | 🇫🇷 Chateaubriant | 166 | 2008 |
| 13 | [VFLIT - Vous faciliter l'IT](https://www.tamtam.ai/c/vflit-vous-faciliter-l-it) (vousfaciliter-it.fr)<br>Providing integrated cybersecurity, cloud, telecom, management applications, and safety services to enhance organizational IT and communication system performance. | Retail Office Equipment | 🇫🇷 Saint-Sébastien-sur-Loire | 164 | 2000 |
| 14 | [MOCA](https://www.tamtam.ai/c/moca) (asi.fr)<br>MOCA by ASI specializes in offering technical expertise and support for Microsoft solutions to users within the Microsoft ecosystem | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 159 | 2022 |
| 15 | [Valeuriad](https://www.tamtam.ai/c/valeuriad) (valeuriad.fr)<br>Experts in transforming complex information systems, providing technical excellence in AI, data engineering, cloud, and infrastructure for large organizations. | IT Services and IT Consulting | 🇫🇷 Nantes | 156 | 2015 |
| 16 | [Capaciti](https://www.tamtam.ai/c/capaciti) (capaciti.com)<br>A regional leader in cybersecurity, providing specialized services in consulting, engineering, and system infrastructure support with offices in France and international project capabilities | IT Services and IT Consulting | 🇫🇷 Carquefou | 150 | 1999 |
| 17 | [KOSMOS](https://www.tamtam.ai/c/kosmos-nantes) (kosmos-education.com)<br>Specializing in digital education solutions, this company implements web portals, e-portfolios, mobile apps, and other digital tools for schools | IT Services and IT Consulting | 🇫🇷 Nantes | 141 | 1998 |
| 18 | [kanoma](https://www.tamtam.ai/c/kanoma) (kanoma.fr)<br>Experts guide clients digital transformation, from design to production, focusing on agile projects, development, product design, and organizational change. | IT Services and IT Consulting | 🇫🇷 Nantes | 128 | 2018 |
| 19 | [Timcod](https://www.tamtam.ai/c/timcod) (timcod.fr)<br>Provider of IT solutions for mobile workers in logistics and transportation, specializing in barcode scanners, Wi-Fi, voice recognition, and RFID technology | IT Services and IT Consulting | 🇫🇷 Carquefou | 118 | 2002 |
| 20 | [proLogistik France (DSIA)](https://www.tamtam.ai/c/prologistik-france-dsia) (logistar-dsia.com)<br>French subsidiary of a pan-European group, publishing, integrating, and hosting supply chain solutions, including WMS, OMS, LMS, TMS, ensuring optimal security and accessibility. | Software Development | 🇫🇷 Nantes | 114 | 1985 |
| 21 | [Mismo Informatique](https://www.tamtam.ai/c/mismo-informatique) (mismo.fr)<br>A comprehensive IT solutions provider offering infrastructure, hardware, software, and services to streamline operations for 3,000 businesses, with certifications and partnerships with industry leaders | IT Services and IT Consulting | 🇫🇷 La Chapelle-sur-Erdre | 113 | 1992 |
| 22 | [A5sys](https://www.tamtam.ai/c/a5sys) (a5sys.com)<br>Founded in 2001, the company specializes in IT services focusing on business intelligence, databases, and application development | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 92 | 2001 |
| 23 | [Le Phare](https://www.tamtam.ai/c/le-phare) (lephare.com)<br>Digital product factory for SMEs, ETIs, and industries Provides digital transformation consulting and custom platforms to accelerate B2B and B2B2C businesses | Technology, Information and Internet | 🇫🇷 Nantes | 87 | 2000 |
| 24 | [Iliane Informatique](https://www.tamtam.ai/c/iliane-informatique) (iliane.fr)<br>Providing comprehensive IT solutions for businesses of all sizes to effectively manage their information systems | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 83 | 1982 |
| 25 | [Mercuria](https://www.tamtam.ai/c/mercuria) (mercuria.fr)<br>Advises and supports businesses with SaaS, Cloud, or hosted solutions for accounting, financial, payroll, and HR management software, working with reliable publishers. | Software Development | 🇫🇷 La Chapelle-sur-Erdre | 82 | 1999 |
| 26 | [mobiappsFr](https://www.tamtam.ai/c/mobiappsfr) (mobiapps.fr)<br>mobiApps specializes in creating multiplatform mobile apps using emerging hybrid technologies like HTML/CSS and JavaScript, along with digital strategy services | Software Development | 🇫🇷 Orvault | 74 | 2014 |
| 27 | [Voxaly](https://www.tamtam.ai/c/voxaly) (voxaly.com)<br>Specialized in electronic voting systems, organizing elections for labor unions, supervisory boards, shareholder meetings for top French companies Customized solutions since 2006 | IT Services and IT Consulting | 🇫🇷 Saint-Herblain | 73 | 2006 |
| 28 | [ELEPHANT Technologies](https://www.tamtam.ai/c/elephant-technologies) (elephant-technologies.fr)<br>Offers expert human-centered tech consultancy, ensuring perfect alignment between client needs and employee skills across various IT domains from idea to production. | IT Services and IT Consulting | 🇫🇷 Nantes | 69 | 2017 |
| 29 | [ABASE](https://www.tamtam.ai/c/abase) (generation-net.org)<br>ABASE 20 is a digital services company providing a variety of digital solutions and services to clients | IT Services and IT Consulting | 🇫🇷 Nantes | 67 | 1993 |
| 30 | [ATÉMIS](https://www.tamtam.ai/c/atemis) (atemis.eu)<br>Providing secure and responsible IT infrastructure design, deployment, and management services tailored to specific organizational needs with local support. | IT Services and IT Consulting | 🇫🇷 La Chapelle-sur-Erdre | 61 | 1997 |

## 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 Loire-Atlantique department

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- [Software Development companies in the Loire-Atlantique department](https://www.tamtam.ai/l/software-development-companies-loire-atlantique) (137)
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- [IT Services and IT Consulting companies in the Loire-Atlantique department](https://www.tamtam.ai/l/it-services-and-it-consulting-companies-loire-atlantique) (110)
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- [Distributors and wholesalers in the Loire-Atlantique department](https://www.tamtam.ai/l/distributors-and-wholesalers-loire-atlantique) (94)
- [Hardware manufacturers in the Loire-Atlantique department](https://www.tamtam.ai/l/hardware-companies-loire-atlantique) (86)
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- [Public sector organisations in the Loire-Atlantique department](https://www.tamtam.ai/l/public-sector-organisations-loire-atlantique) (80)
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- [Education providers in the Loire-Atlantique department](https://www.tamtam.ai/l/education-companies-loire-atlantique) (68)
- [Real Estate companies in the Loire-Atlantique department](https://www.tamtam.ai/l/real-estate-companies-loire-atlantique) (67)
- [Financial services firms in the Loire-Atlantique department](https://www.tamtam.ai/l/financial-services-firms-loire-atlantique) (65)
- [Law Practice companies in the Loire-Atlantique department](https://www.tamtam.ai/l/law-practice-companies-loire-atlantique) (62)
- [Retail companies in the Loire-Atlantique department](https://www.tamtam.ai/l/retail-companies-loire-atlantique) (61)
- [Subscription businesses in the Loire-Atlantique department](https://www.tamtam.ai/l/subscription-businesses-loire-atlantique) (61)
- [Critical infrastructure operators in the Loire-Atlantique department](https://www.tamtam.ai/l/critical-infrastructure-operators-loire-atlantique) (58)
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- [Construction companies in the Loire-Atlantique department](https://www.tamtam.ai/l/construction-companies-loire-atlantique) (57)

## 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 the Hauts-de-Seine department](https://www.tamtam.ai/l/it-services-companies-hauts-de-seine) (737)
- [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)
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- [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 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)

## The same list elsewhere

- [IT services companies in the world](https://www.tamtam.ai/l/it-services-companies-in-the-world) (20,934)
- [IT services companies in Europe](https://www.tamtam.ai/l/it-services-companies-in-europe) (11,376)

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Source: https://www.tamtam.ai/l/it-services-companies-loire-atlantique