| # | Company | Employees |
|---|---|---|
| 1 |
Gartnergartner.com
A global company providing expert-led research and data-driven insights to help executives make faster, smarter decisions and achieve stronger performance |
22,206 |
| 2 |
TRC Companies, Inc.trccompanies.com
Providing advisory, consulting, construction, engineering, and management services to help clients adapt and achieve sustainable, impactful results. |
7,463 |
| 3 |
Electronic Data Systemsdxc.com
A global company founded in 1962 offering electronic data processing management personnel and computer hardware, focusing on large corporations and government contracts |
3,809 |
| 4 |
Daymondaymon.com
Provides end-to-end private brand development services including strategy, product development, quality assurance, supplier management, sales, and branding solutions. |
2,262 |
| 5 |
ISG (Information Services Group)isg-one.com
Global AI-focused technology research and advisory firm helping organizations optimize technology investments and achieve operational excellence and growth. |
2,189 |
| 6 |
Rizingrizing.com
A global SAP partner offering strategy, implementation, and support for SAP HCM, EAM, and Retail/Fashion industries, driving business transformation with industry expertise |
989 |
| 7 |
MMA (Marketing Management Analytics)mma.com
Provides unified marketing and commercial measurement, data management, software, and consulting services to enhance brand value and revenue growth. |
911 |
| 8 |
SDG Corporationsdgc.com
A global provider of technology and consulting services specializing in cybersecurity, identity, and risk management solutions for enterprises worldwide |
754 |
| 9 |
Crisil Coalition Greenwichgreenwich.com
A leading provider of strategic benchmarking and analytics to the financial services industry, offering actionable insights to improve business performance |
660 |
| 10 | 648 | |
| 11 |
SimiTreesimitreehc.com
SimiTree provides a wide range of support services and consulting to post-acute organizations in the healthcare industry to improve performance and revenue |
526 |
| 12 |
Butler Aerospace & Defensebutler.com
Specializing in state-of-the-art, cost-optimized solutions, we cater to Aerospace, Defense, and Federal markets by offering high-end engineering talent and flexible business models |
521 |
| 13 |
Rizing Consumer Industriesrizing.com
Leader in retail and consumer products for SAP software, providing specialized solutions and consulting services to optimize SAP experience worldwide |
505 |
| 14 |
BL Companiesblcompanies.com
Company offering integrated architecture, engineering, environmental sciences, land surveying, and planning services with a focus on quality, employee ownership, and work-life balance |
498 |
| 15 |
USI Consulting Groupusicg.com
A leading retirement plan consulting and benefits administration firm, providing comprehensive guidance and innovative solutions for employers and their employees nationwide |
494 |
| 16 |
Fuss & O'Neillfando.com
A full-service engineering and planning firm with over 95 years of experience, serving public and private sectors across the East Coast |
484 |
| 17 |
LogicSource, Inc.logicsource.com
LogicSource specializes in procurement services for indirect goods, helping brands optimize spending through expertise, technology, and strategic partnerships. |
423 |
| 18 |
AI Engineers, Inc.aiengineers.com
A multidisciplinary engineering firm providing innovative solutions for infrastructure needs, prioritizing accountability, entrepreneurship, innovation, inclusiveness, and transparency to benefit communities |
411 |
| 19 |
Lockwoodthelockwoodgrp.com
The company collaborates with pharmaceutical, biotech, and medical device industries to create evidence-based, impactful strategies and communications for brand development |
405 |
| 20 |
Zaelabzaelab.com
Highly-skilled digital partner advising global B2B organizations on delivering next-generation digital solutions to market |
391 |
| 21 |
Comply Regulatory Servicescomply.com
An advanced provider of compliance and registration products and services for financial institutions, offering expert consulting and education to navigate regulatory requirements |
312 |
| 22 |
Consulting Engineering Services (CES)ceseng.com
Specializes in sustainable MEP/FP engineering for commercial and residential buildings, focusing on energy efficiency, net-zero, and resilient design. |
306 |
| 23 |
EverestDX Inceverestdx.com
A digital platform services company specializing in orchestration, intelligent operations, and AI-powered analytics for enterprise IT to enable seamless digital transformation |
280 |
| 24 |
MTU Aero Engines North Americamtuusa.com
Specializing in complete engineering services for the gas turbine industry, providing design, analysis, project management, and aftermarket engineering solutions tailored to individual needs |
220 |
| 25 |
Maganti IT Resources, LLCmitresource.com
A leading IT Software development and consulting firm, specializing in designing and delivering technology solutions to help clients gain a competitive edge |
198 |
| 26 |
Cyma Systems Inccymasys.com
A technology solutions firm in Connecticut offering services to mid-sized and Fortune 1000 businesses, focused on profitability, innovation, cost reduction, and customer satisfaction |
108 |
| 27 |
Visionary Innovative Technology Solutions LLCvitsus.com
A staffing and consulting firm partnering with clients globally to improve work efficiency and foster relationships across various industries |
99 |
| 28 |
Titan Energytitanenergyne.com
A leading energy consultant providing procurement, on-site generation, and tailored solutions to nonprofit, commercial, and industrial clients across the US |
68 |
| 29 |
Apple Consulting Group Incappleconsultinggroup.com
Innovative consulting firm specializing in new technology, cloud solutions, digital transformation, and business systems improvement across various sectors |
22 |
| 30 | 13 | |
| 31 |
Competitive Resources, Inc.cri-energy.com
A seasoned provider of energy efficiency services, including residential and commercial retrofits, quality assurance, database design, program planning, evaluation, and marketing |
13 |
| 32 |
Winchester Capitalwinchestercapital.com
Privately-owned investment banking firm offering strategic advisory services, international asset management, and expertise in cross-border mergers & acquisitions for global clients |
11 |
| 33 |
Facilities Engineering Associates, P.C.feace.com
A leading engineering consultancy specializing in designing and commissioning datacenters, mission critical facilities, and utility systems for Fortune 500 clients since 1987 |
10 |
| 34 |
Global Finesseglobalfinesse.com
Specialist consultancy providing investment and risk management systems for global banks, insurance companies, and asset management firms in the financial services industry |
9 |
| 35 |
Ketchbrook Analyticsketchbrookanalytics.com
New England analytics consulting firm specializing in data strategy, business intelligence, predictive modeling, model validation, and process automation services |
6 |
| 36 |
MHR Development, LLCmhrdevelopment.com
Specializing in sustainable energy solutions for buildings and campuses, focusing on renewable sources and energy efficiency |
3 |
| 37 |
zlc technologyzlctechnology.com
Business and Technology consulting firm specializing in Digital Transformation, offering expertise in voice, network, cloud, and security through various technology providers Trusted IT advisor |
3 |
Turn this list into pipeline
Tamtam finds the decision-makers at every company on a list like this one, with verified emails, phone numbers and the buying signals that tell you when to reach out.
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 2, 2026.
More company lists in Connecticut
- The largest companies in Connecticut 1,250
- Financial services firms in Connecticut 173
- Manufacturers in Connecticut 143
- Financial Services companies in Connecticut 94
- Education providers in Connecticut 92
- Hardware manufacturers in Connecticut 86
- Critical infrastructure operators in Connecticut 85
- Healthcare providers in Connecticut 79
- Hospitals and Health Care companies in Connecticut 76
- Retail chains in Connecticut 72
- Investment Management companies in Connecticut 72
- Venture capital and private equity firms in Connecticut 66
- Aerospace and defence companies in Connecticut 58
- IT Services and IT Consulting companies in Connecticut 57
- IT services companies in Connecticut 51
- Publicly traded companies in Connecticut 49
- Insurance companies in Connecticut 45
- Contract manufacturers in Connecticut 44
- SaaS companies in Connecticut 44
- Higher Education companies in Connecticut 43
- Public sector organisations in Connecticut 42
- Family-owned companies in Connecticut 39
- Energy companies in Connecticut 37
- Primary and Secondary Education companies in Connecticut 34
The same list elsewhere in United States
- Consulting firms in the United States 4,382
- Consulting firms in California 553
- Consulting firms in New York State 474
- Consulting firms in Texas 453
- Consulting firms in Virginia 283
- Consulting firms in Illinois 238
- Consulting firms in New Jersey 215
- Consulting firms in Florida 186
- Consulting firms in Georgia 168
- Consulting firms in Massachusetts 153
- Consulting firms in Pennsylvania 144
- Consulting firms in Ohio 115
- Consulting firms in Maryland 112
- Consulting firms in Washington State 106
- Consulting firms in Michigan 102
- Consulting firms in North Carolina 85
- Consulting firms in Colorado 77
- Consulting firms in Alabama 74
- Consulting firms in New York 368
- Consulting firms in Chicago 127
- Consulting firms in Houston 99
- Consulting firms in San Francisco 88
- Consulting firms in Atlanta 84
- Consulting firms in Washington 70