These companies with in-house R&D in Connecticut are mostly large firms across various sectors. They include established manufacturers and technology providers. For instance, Xerox offers workplace technology solutions, while Pratt & Whitney designs aircraft propulsion systems. Stanley Black & Decker provides tools and industrial systems, and HARMAN International specializes in audio products and automotive electronics. SS&C Technologies delivers cloud-based software for financial and healthcare industries, and Gartner offers expert-led research and data-driven insights. A notable pattern is the concentration of headquarters in specific cities. For example, Stamford is home to HARMAN International, Gartner, and Tronox. Norwalk hosts Xerox and Terex Corporation, and New Haven is the base for Yale University, Yale School of Medicine, and Yale New Haven Health. This indicates a clustering of research and development activities within these urban centers.
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 | 47,247 | ||||
| 2 |
Pratt & Whitneyrtx.com
Design and manufacture advanced propulsion systems for aircraft, enabling global connectivity, economic growth, and national defense. |
30,378 | |||
| 3 |
Stanley Black & Decker, Inc.stanleyblackanddecker.com
Provider of tools, fasteners, and infrastructure systems supporting home repair, automotive security, construction, and energy industries with innovation and safety. |
29,460 | |||
| 4 |
HARMAN Internationalharman.com
Designs and manufactures premium audio products and automotive electronics, enabling smarter, safer, and immersive in-cabin vehicle experiences worldwide. |
27,936 | |||
| 5 |
SS&C Technologiesssctech.com
Provider of cloud-based software and solutions for financial and healthcare industries, serving over 22,000 companies globally. |
27,478 | |||
| 6 |
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 | |||
| 7 |
Yale Universitynews.yale.edu
Research university fostering global connections, creativity, and innovation, emphasizing student learning and positive worldwide impact. |
19,675 | |||
| 8 |
General Dynamics Electric Boatgdeb.com
Design and build nuclear-powered submarines for the U.S. Navy, including Virginia-class and Columbia-class ballistic missile submarines. |
9,481 | |||
| 9 |
Terex Corporationterex.com
A global manufacturing company focused on building essential machines, improving lives, volunteering, and maintaining a safe, inclusive work environment |
8,109 | |||
| 10 |
Yale School of Medicinemedicine.yale.edu
A world-renowned center for biomedical research, education, and advanced healthcare with affiliations to leading institutions and a unique curriculum promoting independent thinking |
6,960 | |||
| 11 |
Praxair, Inc - a Linde Companylindeus.com
A global leader in industrial gases and engineering, providing high-quality gases, technologies, and services to diverse markets while promoting sustainability and productivity |
6,549 | |||
| 12 |
PerkinElmerperkinelmer.com
A global provider of technology and service solutions for measuring, quantifying, detecting, and reporting in various industries to ensure quality and safety |
6,485 | |||
| 13 |
Tronoxtronox.com
A global producer of titanium dioxide and inorganic chemicals, specializing in mining, processing, and manufacturing products for various industries worldwide |
5,877 | |||
| 14 |
Sikorskylockheedmartin.com
A global leader in helicopter technology, providing innovative and safe flight solutions for commercial and military markets worldwide since 1939 |
5,753 | |||
| 15 |
Yale New Haven Healthynhhs.org
A healthcare organization with five hospitals offering advanced medical treatments, research, and innovations, along with access to primary care physicians and specialists |
5,708 | |||
| 16 |
Amphenolamphenol.com
A Fortune 500 manufacturer with 90,000 employees worldwide, providing key components for electronic devices and networks in daily use |
5,559 | |||
| 17 |
Crane Companycraneco.com
Long-standing ethical business focused on innovation, disciplined management, strategic acquisitions, and creating value for customers, suppliers, and shareholders. |
4,696 | |||
| 18 |
IMS Healthiqvia.com
Provides healthcare data, analytics, and technology solutions to improve clinical, commercial, and real-world outcomes in the life sciences industry. |
4,675 | |||
| 19 |
Interactive Brokersinteractivebrokers.com
Provides automated trade execution and custody for diverse financial instruments across global markets, offering advanced tools and research at low cost. |
3,506 | |||
| 20 |
Hexcel Corporationhexcel.com
Production of carbon fiber reinforcements, resin systems, and honeycomb materials focused on lightweight solutions for commercial aerospace industry. |
3,357 | |||
| 21 |
Edgewell Personal Careedgewell.com
Global personal care company with 25+ brands, serving 50+ countries, focusing on efficiency, sustainability, and inclusive workplace culture. |
3,354 | |||
| 22 |
Amphenol Communications Solutionsamphenol-cs.com
Design and manufacture innovative connectors and cable assemblies for communications, mobile, RF, optics, data centers, networking, industrial, and automotive applications. |
3,169 | |||
| 23 |
Southern Connecticut State Universitysouthernct.edu
This institution offers diverse, quality graduate and undergraduate education in liberal arts and professional disciplines, emphasizing academic excellence, social justice, and public service |
2,666 | |||
| 24 |
Connecticut Children'sconnecticutchildrens.org
A leading pediatric academic medical center dedicated to advancing pediatric care through medical innovation, technology, research, and specialized healthcare services |
2,621 | |||
| 25 |
Conair LLCconair.com
Design and manufacture of personal care, kitchen appliances, cookware, hair accessories, cosmetic and travel products sold globally. |
2,093 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 26 |
Cristaltronox.com
A leading producer of titanium dioxide and zircon products, with a global footprint in mining, processing, and sale of mineral sands |
2,050 | |||
| 27 |
Hamilton Sundstrandhamiltonsundstrand.com
A global supplier of aerospace and industrial products, designing and manufacturing systems for aircraft and international space programs |
1,918 | |||
| 28 |
CooperSurgicalcoopersurgical.com
This company is focused on advancing women's, babies', and families' healthcare worldwide through products and services for reproductive solutions and gynecological care |
1,845 | |||
| 29 |
Timex Grouptimexgroup.com
Design, manufacture, and market innovative watches globally under multiple renowned brands, employing over 3,000 people worldwide. |
1,624 | |||
| 30 |
Linde Gas & Equipmentlindedirect.com
A trusted provider of industrial gases, welding supplies, cutting machines, and automation, offering solutions to reduce costs and increase productivity |
1,552 | |||
| 31 |
GeneDxgenedx.com
Specializing in genetic diagnosis, offering exome and genome tests to provide personalized health plans, accelerate drug discovery, and improve health system efficiencies |
1,260 | |||
| 32 |
Aurobindo Pharma USA, Inc.aurobindousa.com
Provider of affordable generic pharmaceuticals with a broad portfolio of over 150 product families across various therapeutic categories Recognized for rapid growth and high prescription dispensing |
1,198 | |||
| 33 |
RBC Bearingsrbcbearings.com
International manufacturer of precision bearings, specializing in highly technical and regulated products for industrial, aerospace, and defense markets Offers unique design solutions and exceptional quality |
1,106 | |||
| 34 |
TRUMPF North Americatrumpf.com
Leading provider of sheet metal fabrication machinery and industrial lasers, focusing on innovative, networked manufacturing solutions in North America. |
987 | |||
| 35 |
MacDermid Enthone Industrial Solutionsmacdermidenthone.com
Global leader in manufacturing chemical compounds for surface coating applications, offering innovative solutions, sustainable technologies, and technical support to meet customer needs |
961 | |||
| 36 |
AQR Capital Managementaqr.com
Global investment management firm combining economics, behavioral finance, data, and technology to optimize client portfolio performance worldwide. |
957 | |||
| 37 |
United States Department of the Air Forceaf.mil
This company is one of the three Military Departments in the US Department of Defense, encompassing the USAF and USSF |
840 | |||
| 38 |
MannKind Corporationmannkindcorp.com
This company focuses on developing and commercializing therapeutic products and devices for endocrine and orphan lung diseases, aiming to improve patients' lives |
833 | |||
| 39 |
Dorel Sportsprivacy.ponbike.com
A global company within Dorel Industries, committed to helping consumers find their perfect ride through innovative cycling products in over 100 countries |
825 | |||
| 40 |
Mastercammastercam.com
Develops and supplies advanced CAD/CAM software for diverse manufacturing processes, enabling precision, productivity, and performance for various industries globally. |
809 | |||
| 41 |
Ensign-Bickford Aerospace & Defense Company (EBAD)ebad.com
Global leader in precision energetics systems and explosive solutions, offering customized hardware and systems solutions for aerospace and defense missions worldwide |
734 | |||
| 42 |
LATICRETE Internationaleu.laticrete.com
Manufactures construction solutions: tile, masonry, flooring finishes, concrete chemicals, restoration systems; offers sustainable products for LEED certification with strong warranties. |
694 | |||
| 43 |
MacDermid Performance Solutionsmacdermid.com
Manufacture specialty chemicals and materials for electronics, printing, plating, and offshore oil industries using advanced technological processes. |
622 | |||
| 44 |
Cannondalecannondale.com
Innovative bicycle company since 1971, focused on inspiring the world to ride and improving cycling through relentless innovation and global reach |
611 | |||
| 45 |
The Lee Companytheleeco.com
A pioneer in miniature precision fluid control components for various industries, specializing in miniaturization and engineering expertise for cutting-edge fluid flow technology |
588 | |||
| 46 |
CooperSurgical Fertility Solutionscoopersurgical.com
Global leader in IVF and reproductive genetics, providing innovative products and services for every step in the assisted reproductive technology journey. |
578 | |||
| 47 |
GameChange Energygamechangeenergy.com
A manufacturer of solar racking systems, GameChange Solar offers fast installation, bankable quality, and high value through superior engineering and design |
542 | |||
| 48 |
Davis-Standarddavis-standard.com
Global leader in extrusion and converting technology, offering innovative solutions across multiple industries with a focus on efficiency and sustainability |
538 | |||
| 49 |
Gerber Technology, a Lectra Companylectra.com
A global provider of software and automation solutions in fashion, automotive, and furniture industries, with a focus on innovation and technology |
522 | |||
| 50 | 513 | ||||
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 12, 2026.
More company lists in Connecticut
- The largest companies in Connecticut 1,247
- Multinational companies in Connecticut 220
- Financial services firms in Connecticut 172
- Manufacturers in Connecticut 143
- Education providers in Connecticut 92
- Financial Services companies 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
- Professional services firms in Connecticut 54
- 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
- Companies with a mobile app in Connecticut 43
- Higher Education companies in Connecticut 43
- Public sector organisations in Connecticut 42
The same list elsewhere in United States
- Companies with in-house R&D in the United States 6,796
- Companies with in-house R&D in California 1,275
- Companies with in-house R&D in Texas 442
- Companies with in-house R&D in New York State 419
- Companies with in-house R&D in Massachusetts 396
- Companies with in-house R&D in Illinois 322
- Companies with in-house R&D in Michigan 287
- Companies with in-house R&D in Ohio 277
- Companies with in-house R&D in Pennsylvania 255
- Companies with in-house R&D in New Jersey 224
- Companies with in-house R&D in Florida 221
- Companies with in-house R&D in Alabama 215
- Companies with in-house R&D in Georgia 173
- Companies with in-house R&D in Virginia 166
- Companies with in-house R&D in North Carolina 158
- Companies with in-house R&D in Wisconsin 154
- Companies with in-house R&D in Minnesota 146
- Companies with in-house R&D in Washington State 140
- Companies with in-house R&D in Colorado 113
- Companies with in-house R&D in Maryland 107
- Companies with in-house R&D in Indiana 104
- Companies with in-house R&D in New York 223
- Companies with in-house R&D in San Francisco 147
- Companies with in-house R&D in Houston 129