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Top 30 consulting firms in the Essonne department

Tamtam tracks 40 consulting firms headquartered in the Essonne department. This list ranks the 30 largest by number of employees on LinkedIn, led by APIXIT, G4 and NBTECH. Their median headcount is 36. Half of them were founded in 2007 or later. The most common headquarters are Massy (7), Les Ulis (5) and Gif-sur-Yvette (2).

🇫🇷 Essonne30 companiesUpdated Nov 11, 2026

The consulting firms in Essonne are predominantly mid-sized companies specialized in engineering and IT services. APIXIT provides cybersecurity, infrastructure, and cloud solutions. NBTECH offers technical studies and industrial engineering for various sectors. ADVANCE Engineering focuses on complex nuclear projects, and DSI GROUP is an engineering services company emphasizing staff development.

Most of these firms, such as G4 in information management, Cyrias in cloud solution integration, and EZYTAIL in supply chain management, were founded between 2006 and 2018. A notable concentration of headquarters is observed in Les Ulis and Massy, indicating these areas as key hubs for consulting activities within the department.

#CompanyIndustryHeadquarters EmployeesFounded
1
APIXITapixit.fr

Provides cybersecurity, infrastructure, and cloud solutions, supporting clients through audits, consulting, integration, maintenance, and managed services for digital transformation.

IT Services and IT Consulting 🇫🇷 Les Ulis 303 1992
2
G4g4.fr

G4 specializes in streamlining information management within companies, optimizing tools for strategic alignment and providing practical support and expertise

Information Services 🇫🇷 Arpajon 254 2006
3
NBTECHnbtech.fr

Technical studies, technology consulting, and industrial engineering services for automotive, aerospace, railway, and industrial maintenance sectors across France.

Engineering Services 🇫🇷 Les Ulis 244 2014
4
DSI GROUPgroup-dsi.com

An engineering services company within the DSI GROUP, prioritizing staff development and customer relationships with a focus on flexibility and customer loyalty

IT Services and IT Consulting 🇫🇷 Massy 225 2007
5
ADVANCE Engineeringadvance-eng.fr

ADVANCE Engineering, a subsidiary of CERAP Prévention, specializes in providing technical engineering services for complex projects in the nuclear sector

Engineering Services 🇫🇷 Les Ulis 205 2012
6
CERC (Cardiovascular European Research Center)cerc-europe.org

A leading European CRO founded by experienced physicians, specializing in clinical research, innovative techniques, and supporting young scientific leaders globally

Research Services 🇫🇷 Massy 84 2008
7
PROTECTICprotectic.fr

Engineering company, intervening in large-scale industrial projects (aeronautics, space, defense, energy, transport). Accompanying major industrial players in product development.

IT Services and IT Consulting 🇫🇷 Bièvres 50 1983
8
DAF CONSEILdafconseil.com

Specializes in automotive technical training, support, consulting, engineering, and web-based SaaS solutions for repair industry professionals.

Motor Vehicle Manufacturing 🇫🇷 Lisses 49 2006
9
SOL CONSEILvertical-sea.com

Geotechnical consulting firm with over 35 years of experience offering services such as soil investigation, foundation design, and project management

Civil Engineering 🇫🇷 Massy 43 1982
10
Junior CentraleSupélecjuniorcs.fr

Junior CentraleSupélec is a student-run consulting firm offering services in digital, electronics, strategy, data analytics, and environment sectors with over 4500 future engineering graduates

IT Services and IT Consulting 🇫🇷 Gif-sur-Yvette 42 1969
11
Cyriascyrias.com

Consulting and integration company specializes in assisting Purchasing and Finance Departments with implementing Cloud Solutions, offering expertise in digital transformation projects

Software Development 🇫🇷 Massy 42 2018
12
STYRELstyrel.fr

Engineering and training services specializing in industrial IT, embedded real-time computing, custom industrial PCs, test benches, and complete system integration.

Software Development 🇫🇷 Le Plessis-Pâté 41 1984
13
EZYTAILezytail.com

Industrial supply chain management providing back office software, mutualized logistics, transportation solutions, ERP integration, and consulting for new and existing multi-channel retailing businesses.

Software Development 🇫🇷 Grigny 41 2010
14
SOCASSsocass.fr

Specialized consulting company focusing on maintenance, operations, technology engineering, and innovation for industrial and tertiary sectors with a human-centered approach

Engineering Services 🇫🇷 Les Ulis 39 2007
15
CREATYM Francecreatym-france.com

Specialized in engineering services, technical consulting, and studies for industrial actors, prioritizing human-centric approach, teamwork, and passion for technology to enhance client services

Industrial Machinery Manufacturing 🇫🇷 Massy 36 2013

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16
CONSTRUIREconstruire-sa.fr

The company provides engineering services for various industries, offering expertise in developing innovative solutions and technical support

Construction 🇫🇷 Dourdan 31 2019
17
IDETEC Environnementsites.google.com

IDETEC Environment is a leading player in monitoring engineering, providing services from network diagnostics to site supervision, with a focus on quality and accreditation

Engineering Services 🇫🇷 Villebon-sur-Yvette 30 2000
18
Infass Systèmesinfass.com

Development of tailored software solutions for insurance, temporary work, petroleum storage, and point-to-point transport industries with specialized expertise.

Software Development 🇫🇷 Montgeron 29 1973
19
Aryason Consultingaryason.fr

Massy based firm specialized in providing professional advice on computer systems and software solutions with seven years of industry experience.

Software Development 🇫🇷 Massy 26 2013
20
CPP-SYSTEM

A consulting and IT service company operating in Madagascar and France, specialized in digital payment, customer loyalty, and management solutions Coming soon!

IT Services and IT Consulting 🇫🇷 Ballainvilliers 24 n/a
21
iNet Systeminet-system.com

A Paris-based company offers Apple technology advice, product resale, installation, integration, support contracts, and software development services

Software Development 🇫🇷 Bièvres 14 2004
22
IPC - Groupe Gengisipc-gengis.fr

A reliable partner providing tailored solutions in structural engineering since 1998, navigating complex regulations and economic challenges with a focus on client needs

Engineering Services 🇫🇷 Palaiseau 14 1998
23
Soler Conseilsolerconseil.fr

A geotechnical engineering consulting firm with a laboratory, offering services from project initiation to completion, led by experienced professionals

Real Estate 🇫🇷 Massy 10 1986
24
Sol Paysagesolpaysage.fr

Sol Paysage is an environmental consultancy specializing in landscape design, soil, and biodiversity They work on various scales from large territories to gardens, focusing on sustainable development

Environmental Services 🇫🇷 Orsay 10 1995
25
KAPSIKUMkapsikum.com

KAPSIKUM supports the healthcare industries through its services and solutions

Business Consulting and Services 🇫🇷 Saclay 10 2022
26
INGCADingcad.fr

INGCAD is a specialized engineering consulting firm focusing on Civil Engineering drawing, with a dynamic team committed to meeting client needs

Civil Engineering 🇫🇷 Saclay 8 2016
27
AËXORaexor.eu

AEXOR is an engineering firm specializing in ATEX industrial risk solutions, training, certification, chemical risk assessment, and pilot project development in various fields

Research Services 🇫🇷 Les Ulis 7 2007
28
Newasysnewasys.com

NEWASYS provides water consulting services to industries, communities, and private entities, focusing on reducing water consumption and promoting the reuse of non-conventional water sources

Water, Waste, Steam, and Air Conditioning Services 🇫🇷 Gif-sur-Yvette 7 n/a
29
ATLANTIS GEOTECHNIQUEatlantis-geotechnique.fr

Expert geotechnical consulting office providing comprehensive soil studies, hydrogeological analysis, and pollution assessments for construction, infrastructure, and land development projects across France.

Construction 🇫🇷 Ris-Orangis 6 2024
30
ACTUAL PME, Conseil et Expertise Comptableactualpme.fr

A consulting and accounting firm with two agencies in Essonne, offering financial, legal, tax, management, and social advisory services to businesses

Accounting 🇫🇷 Linas 6 n/a

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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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