# Top 30 professional services firms in Fairfax
Tamtam tracks 30 professional services firms headquartered in Fairfax. This list ranks all of them by number of employees on LinkedIn, led by ECS, GovCIO and Dewberry. Their median headcount is 371. Half of them were founded in 1998 or later.
This selection of professional services firms in Fairfax includes a notable concentration of companies specializing in IT system and data services, alongside engineering and business consulting. Many of these firms serve government clients, leveraging advanced technology and specialized expertise. Examples include ECS, which provides advanced technology solutions for cyber threats; GovCIO, delivering IT solutions for government operations; and Dewberry, an engineering firm solving complex challenges for public and private sectors. Other firms like Crestline Hotels & Resorts manage hospitality properties, and BARE International conducts customer experience research.
๐บ๐ธ Fairfax ยท 30 companies ยท Updated Nov 11, 2026
| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [ECS](https://www.tamtam.ai/c/ecs-fairfax) (ecstech.com)
ECS provides advanced technology, science, and digital solutions to address cyber threats for customers in the public and private sectors | IT System Data Services | ๐บ๐ธ Fairfax | 3,996 | 1993 |
| 2 | [GovCIO](https://www.tamtam.ai/c/govcio) (govcio.com)
Deliver IT solutions and services using Agile methods and innovation to optimize government operations and support citizen-focused missions. | IT System Data Services | ๐บ๐ธ Fairfax | 3,164 | 2010 |
| 3 | [Dewberry](https://www.tamtam.ai/c/dewberry) (dewberry.com)
A market-leading firm providing professional services to public and private sector clients, solving complex challenges, and transforming communities through innovation and expertise | Engineering Services | ๐บ๐ธ Fairfax | 2,914 | 1956 |
| 4 | [Crestline Hotels & Resorts](https://www.tamtam.ai/c/crestline-hotels-and-resorts) (crestlinehotels.com)
Hotel management company overseeing 129 properties with over 18,300 rooms nationwide, affiliated with renowned brands like Hilton, Marriott, and Hyatt | Hospitality | ๐บ๐ธ Fairfax | 1,030 | 2000 |
| 5 | [BARE International](https://www.tamtam.ai/c/bare-international) (bareinternational.com)
Global leader in customer experience research, providing customized solutions and actionable feedback to businesses worldwide for over 35 years | Market Research | ๐บ๐ธ Fairfax | 869 | 1987 |
| 6 | [Riverside Research](https://www.tamtam.ai/c/riverside-research) (riversideresearch.org)
A nonprofit organization conducting independent research in various scientific fields to advance innovation and provide high-value solutions to government customers | Research Services | ๐บ๐ธ Fairfax | 801 | 1967 |
| 7 | [IonIdea](https://www.tamtam.ai/c/ionidea) (ionidea.com)
A technology and business process solutions company focused on delivering excellent products, innovative technologies, and high-quality services through passionate professionals and best practices | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 783 | 1991 |
| 8 | [GSA National](https://www.tamtam.ai/c/gsa-national) (gsanational.com)
GSA National assists government contractors with compliance, cost efficiency, and employee benefit program administration, providing consulting, training, compliance analysis, and audit preparation services | Insurance and Employee Benefit Funds | ๐บ๐ธ Fairfax | 521 | 1991 |
| 9 | [MBP (McDonough Bolyard Peck)](https://www.tamtam.ai/c/mbp-mcdonough-bolyard-peck) (mbpce.com)
A multi-disciplined consulting firm specializing in innovative solutions for infrastructure and facility needs, maximizing owner investments and reducing asset costs | Business Consulting and Services | ๐บ๐ธ Fairfax | 478 | 1989 |
| 10 | [All Native Group, The Federal Services Division of Ho-Chunk Inc.](https://www.tamtam.ai/c/all-native-group-the-federal-services-division-of-ho-chunk-inc) (allnativegroup.com)
A government services provider offering training, health services, IT/telecommunications, staffing, professional services, and program management with key certifications | Government Relations Services | ๐บ๐ธ Fairfax | 445 | 1999 |
| 11 | [UCS](https://www.tamtam.ai/c/ucs) (ucs-inc.com)
A rapidly growing government contractor providing Enterprise IT Solutions and Health Services to improve performance across all levels of government | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 432 | 2000 |
| 12 | [PEG](https://www.tamtam.ai/c/peg) (pegenv.com)
Specializing in energy and environmental sustainability programs and policies, offering mechanical engineering, energy efficiency, and built environment consulting services to diverse industries | Engineering Services | ๐บ๐ธ Fairfax | 408 | 1998 |
| 13 | [WR Systems](https://www.tamtam.ai/c/wr-systems) (wrsystems.com)
Design and integration of maritime navigation systems, support for Navy and Coast Guard vessels, radar signal processing expertise, and technical sustainment services. | Maritime Transportation | ๐บ๐ธ Fairfax | 406 | 1983 |
| 14 | [ControlCase](https://www.tamtam.ai/c/controlcase) (controlcase.com)
IT compliance company providing peace of mind through proactive, innovative solutions, automation, and comprehensive services for various regulatory requirements in on-premise and cloud environments | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 392 | 2004 |
| 15 | [CC Pace](https://www.tamtam.ai/c/cc-pace) (ccpace.com)
A business & IT consulting firm in Fairfax, Virginia offering Business & Data Consulting, Digital Services, Agile Transformation, and technology staffing solutions nationwide | Staffing and Recruiting | ๐บ๐ธ Fairfax | 371 | 1980 |
| 16 | [INTEGRITYOne Partners](https://www.tamtam.ai/c/integrityone-partners) (ionep.com)
A business and technology services company specializing in helping Federal Government organizations address challenges and implement effective solutions | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 359 | 2001 |
| 17 | [PE Systems, Inc.](https://www.tamtam.ai/c/pe-systems-inc) (pesystems.com)
Technical capabilities provider with flexible, mission-oriented teams meeting customer requirements Certified SDVOB & MOB, offering great benefits and recognized as Best Place to Work in Dayton | Defense and Space Manufacturing | ๐บ๐ธ Fairfax | 323 | 1971 |
| 18 | [ICF Macro](https://www.tamtam.ai/c/icf-macro) (icf.com)
The company, now part of ICF, serves various markets and offers job opportunities through its website | Business Consulting and Services | ๐บ๐ธ Fairfax | 183 | |
| 19 | [Hadiamondstar Software Solutions LLC](https://www.tamtam.ai/c/hadiamondstar-software-solutions-llc) (hadiamondstar.com)
A global IT services company specializing in consulting and implementing solutions to help businesses re-engineer and compete successfully in the marketplace | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 104 | 2005 |
| 20 | [Harrity & Harrity, LLP](https://www.tamtam.ai/c/harrity-and-harrity-llp) (harrityllp.com)
A top patent firm specializing in electrical and mechanical technology areas, known for high quality, experienced professionals, innovation, and outstanding service | Law Practice | ๐บ๐ธ Fairfax | 102 | 1999 |
| 21 | [Riverside Technology, inc.](https://www.tamtam.ai/c/riverside-technology-inc) (css-inc.com)
Provides innovative IT solutions for environmental decision support systems, using various environmental data sources for informed stakeholder decisions. | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 70 | 1985 |
| 22 | [The Wolf Group, PC](https://www.tamtam.ai/c/the-wolf-group-pc) (thewolfgroup.com)
A Washington, DC-based professional services provider specializing in global wealth management, international tax services, and business solutions for individuals and corporations | Financial Services | ๐บ๐ธ Fairfax | 51 | 1983 |
| 23 | [DAGER Technology, LLC](https://www.tamtam.ai/c/dager-technology-llc) (dagertechnology.com)
A technology company in Fairfax supporting operational users in combating terrorism by providing innovative solutions, assessments, and customer service | Technology, Information and Internet | ๐บ๐ธ Fairfax | 25 | 2010 |
| 24 | [Tiber Solutions LLC](https://www.tamtam.ai/c/tiber-solutions-llc) (tibersolutions.com)
A consultancy specializing in Data Warehousing and Analytics, helping government and commercial clients make better decisions through data-driven solutions | Information Services | ๐บ๐ธ Fairfax | 16 | 2005 |
| 25 | [Rotunda Solutions](https://www.tamtam.ai/c/rotunda-solutions) (rotundasolutions.com)
A SDVOSB specializing in data analytics and data science consulting for federal and commercial clients | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 15 | 2015 |
| 26 | [Adaptalytics, LLC](https://www.tamtam.ai/c/adaptalytics-llc) (adaptalytics.com)
A leading data analytic consulting firm specializing in using data, technology, scientific methods, and creativity to solve complex business problems | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 13 | 2012 |
| 27 | [Mahandru Associates](https://www.tamtam.ai/c/mahandru-associates) (mahandruassociates.com)
A global conglomerate offering advisory services for business migration, mergers, acquisitions, liquidation, and consultancy to investors and entrepreneurs worldwide | Business Consulting and Services | ๐บ๐ธ Fairfax | 11 | 2012 |
| 28 | [NumInformatics Inc.](https://www.tamtam.ai/c/numinformatics-inc) (numinformatics.com)
Consulting firm specializing in data analytics, machine learning, and AI technologies with experienced data scientists and consultants serving private, public, and government sectors | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 8 | |
| 29 | [Everware-CBDI](https://www.tamtam.ai/c/everware-cbdi)
A technology consulting firm specializing in service-oriented application modernization, enterprise architecture, and model-driven development for government and commercial clients | IT Services and IT Consulting | ๐บ๐ธ Fairfax | 7 | 1997 |
| 30 | [The Susan Hicks Group, PC](https://www.tamtam.ai/c/the-susan-hicks-group-pc) (hcj-law.com)
A dedicated law firm in northern Virginia specializing in family law, providing customized legal services tailored to each client's needs | Law Practice | ๐บ๐ธ Fairfax | 3 | |
## 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 Fairfax
- [The largest companies in Fairfax](https://www.tamtam.ai/l/largest-companies-fairfax) (139)
- [IT Services and IT Consulting companies in Fairfax](https://www.tamtam.ai/l/it-services-and-it-consulting-companies-fairfax) (36)
- [IT services companies in Fairfax](https://www.tamtam.ai/l/it-services-companies-fairfax) (34)
## The same list elsewhere in United States
- [Professional services firms in the United States](https://www.tamtam.ai/l/professional-services-firms-united-states) (7,078)
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- [Professional services firms in Maryland](https://www.tamtam.ai/l/professional-services-firms-maryland) (176)
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- [Professional services firms in Atlanta](https://www.tamtam.ai/l/professional-services-firms-atlanta) (143)
- [Professional services firms in San Francisco](https://www.tamtam.ai/l/professional-services-firms-san-francisco) (130)
- [Professional services firms in Washington](https://www.tamtam.ai/l/professional-services-firms-washington) (109)
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Source: https://www.tamtam.ai/l/professional-services-firms-fairfax