# Consulting firms headquartered in Irvine

Tamtam tracks 30 consulting firms headquartered in Irvine. This list ranks all of them by number of employees on LinkedIn, led by Alliant Insurance Services, Salas O'Brien and ADEC Innovations. Their median headcount is 390. Half of them were founded in 2002 or later.

The consulting firms in Irvine include a mix of large established companies and younger firms, primarily focused on IT services, environmental solutions, and general business consulting. Among them, Alliant Insurance Services provides insurance brokerage and consulting, Salas O'Brien is an employee-owned engineering firm, and ADEC Innovations specializes in ESG needs and sustainability performance. Trace3 focuses on data, security, and cloud solutions.

Many of these firms, such as Caylent and Neudesic, an IBM Company, specialize in IT services and consulting, often with a focus on cloud technologies or digital modernization. A common thread across these companies is their emphasis on providing strategic guidance and technological solutions to help businesses transform and improve their operations.

🇺🇸 Irvine · 30 companies · Updated Nov 12, 2026

| # | Company | Industry | Headquarters | Employees | Founded |
|---|---|---|---|---|---|
| 1 | [Alliant Insurance Services](https://www.tamtam.ai/c/alliant-insurance-services) (alliant.com)<br>Provides innovative insurance brokerage and consulting services, supporting diverse clients with expert teams to help grow businesses and communities. | Insurance Agencies and Brokerages | 🇺🇸 Irvine | 6,616 | 1925 |
| 2 | [Salas O'Brien](https://www.tamtam.ai/c/salas-o-brien) (salasobrien.com)<br>Employee-owned engineering firm focused on advancing the human experience through the built environment Top-ranked, with a strong emphasis on impact and sustainability | Engineering Services | 🇺🇸 Irvine | 2,295 | 1975 |
| 3 | [ADEC Innovations](https://www.tamtam.ai/c/adec-innovations) (adec-innovations.com)<br>ADEC Innovations offers integrated industry expertise, data management, and software services to meet ESG needs, improve sustainability performance, and drive operational efficiencies globally | Business Consulting and Services | 🇺🇸 Irvine | 1,801 |  |
| 4 | [Trace3](https://www.tamtam.ai/c/trace3) (trace3.com)<br>Consulting on, integrating, and operating data, security, and cloud solutions to drive business transformation and create measurable value for clients | IT Services and IT Consulting | 🇺🇸 Irvine | 1,440 | 2002 |
| 5 | [Caylent](https://www.tamtam.ai/c/caylent) (caylent.com)<br>Cloud native services provider helping organizations optimize people and technology with AWS, enabling innovation and ambitious ideas to thrive | IT Services and IT Consulting | 🇺🇸 Irvine | 899 | 2015 |
| 6 | [NTrust](https://www.tamtam.ai/c/ntrust) (ntrustinfotech.com)<br>Real estate lease administration solution provider offering advanced CRE software platforms and technical/back office services to international and domestic companies of all sizes | Real Estate | 🇺🇸 Irvine | 814 |  |
| 7 | [Neudesic, an IBM Company](https://www.tamtam.ai/c/neudesic-an-ibm-company) (neudesic.com)<br>Trusted technology partner specializing in digital modernization, custom application development, managed services, and business software products for impactful business results | IT Services and IT Consulting | 🇺🇸 Irvine | 800 | 2002 |
| 8 | [FCS](https://www.tamtam.ai/c/fcs) (firstcarbonsolutions.com)<br>Leading provider of environmental, sustainability, and compliance solutions with expertise in CEQA/NEPA, compliance, permitting, natural resources management, and more Join our team! | Environmental Services | 🇺🇸 Irvine | 613 | 1982 |
| 9 | [Hitachi Solutions America](https://www.tamtam.ai/c/hitachi-solutions-america) (global.hitachi-solutions.com)<br>Global IT consulting firm specializing in Microsoft platform solutions, delivering sustainable business modernization and empowering customer growth worldwide. | IT Services and IT Consulting | 🇺🇸 Irvine | 589 | 1971 |
| 10 | [LSA](https://www.tamtam.ai/c/lsa) (lsa.net)<br>A diversified environmental, transportation, and community planning firm offering expert services in various fields, operating across nine California offices | Environmental Services | 🇺🇸 Irvine | 582 | 1976 |
| 11 | [Altezzasys INC](https://www.tamtam.ai/c/altezzasys-inc) (altezzasys.com)<br>A global technology services provider offering staffing, outsourcing, consulting, and digital solutions to align technology innovation with business strategy worldwide | IT Services and IT Consulting | 🇺🇸 Irvine | 571 | 2014 |
| 12 | [Trio](https://www.tamtam.ai/c/trio) (trioadvisory.com)<br>Global energy and sustainability advisory helping large clients transition to a net-zero future through strategy, implementation, and advanced technological solutions | Business Consulting and Services | 🇺🇸 Irvine | 475 | 2013 |
| 13 | [Resources Global Professionals](https://www.tamtam.ai/c/resources-global-professionals) (rgp.com)<br>Specializing in enterprise risk management consulting to help businesses identify, assess, and mitigate risks for improved decision-making and operational success | Business Consulting and Services | 🇺🇸 Irvine | 459 | 1996 |
| 14 | [Vision33](https://www.tamtam.ai/c/vision33) (vision33.com)<br>Company provides ERP, automation, and integration solutions to help organizations grow, offering consulting and technology services to overcome business challenges and achieve goals globally | Software Development | 🇺🇸 Irvine | 402 | 2003 |
| 15 | [Authority Partners](https://www.tamtam.ai/c/authority-partners) (authoritypartners.com)<br>Global technology strategy consulting and custom software development company delivering digital transformation solutions to increase engagement, sales, productivity, and create value for clients | IT Services and IT Consulting | 🇺🇸 Irvine | 390 | 1998 |
| 16 | [SMA: The Program Lifecycle Company](https://www.tamtam.ai/c/sma-the-program-lifecycle-company) (smawins.com)<br>SMA helps companies enhance competitiveness through consulting, program management, and technical support, guided by values of professionalism, impact, and courage | Professional Services | 🇺🇸 Irvine | 311 | 1982 |
| 17 | [SETA International](https://www.tamtam.ai/c/seta-international) (seta-international.com)<br>Global leader in custom software development, specializing in end-to-end technology services and solutions for over 500 clients across a variety of industries worldwide | IT Services and IT Consulting | 🇺🇸 Irvine | 278 | 2008 |
| 18 | [Interwest Consulting Group](https://www.tamtam.ai/c/interwest-consulting-group) (interwestgrp.com)<br>Professional consulting services for public agencies in California, Nevada, and Colorado Expert team with experience in public works, engineering, and building departments, focusing on thriving communities | Government Administration | 🇺🇸 Irvine | 233 | 2002 |
| 19 | [XCentium](https://www.tamtam.ai/c/xcentium) (xcentium.com)<br>Aligning technology strategy with business goals, delivering digital experiences, and modernizing platforms for long-term success through tailored solutions. | IT Services and IT Consulting | 🇺🇸 Irvine | 207 | 2011 |
| 20 | [RBF Consulting, a Company of Michael Baker International](https://www.tamtam.ai/c/rbf-consulting-a-company-of-michael-baker-international) (rbf.com)<br>A leading civil engineering and design firm providing a wide range of services for public, governmental, and private organizations worldwide | Civil Engineering | 🇺🇸 Irvine | 205 | 1944 |
| 21 | [eJAmerica](https://www.tamtam.ai/c/ejamerica) (ejamerica.com)<br>The company provides a range of digital services including application, cyber security, IT consulting, data center, cloud services, and IT staffing They also offer management consulting, ERP solutions, and outsourcing strategies | IT Services and IT Consulting | 🇺🇸 Irvine | 183 | 2016 |
| 22 | [Leighton - A Verdantas Company](https://www.tamtam.ai/c/leighton-a-verdantas-company) (verdantas.com)<br>A company providing environmental, geotechnical, materials testing, and inspection services with a team of engineers, geologists, technicians, and inspectors Offering various job opportunities | Civil Engineering | 🇺🇸 Irvine | 182 | 1961 |
| 23 | [Approgence Technologies Inc](https://www.tamtam.ai/c/approgence-technologies-inc) (approgence.com)<br>IT services company offering systems integration, software solutions, staff augmentation, BI, Analytics, Data management, mobile apps, ERP integration, and executive search services | IT Services and IT Consulting | 🇺🇸 Irvine | 16 | 2006 |
| 24 | [Sovereign Power](https://www.tamtam.ai/c/sovereign-power) (sovereignpower.com)<br>This company partners with clients to develop enterprise strategies using exponential technologies, focusing on digital transformation, innovation, and revenue growth | IT Services and IT Consulting | 🇺🇸 Irvine | 9 | 2015 |
| 25 | [Real Estate Economics](https://www.tamtam.ai/c/real-estate-economics) (zondahome.com)<br>A market research company providing web-based analytic tools and consulting services to the homebuilding industry for informed decision-making | Real Estate | 🇺🇸 Irvine | 7 | 1995 |
| 26 | [Cloudpointe](https://www.tamtam.ai/c/cloudpointe) (cloudpointe.com)<br>A customer-centric Salesforce consultancy in Southern California helping mid-to-large companies solve business challenges with strategic planning, integration, development, and ongoing support | IT Services and IT Consulting | 🇺🇸 Irvine | 6 | 2017 |
| 27 | [Proaxive Solutions,LLC](https://www.tamtam.ai/c/proaxive-solutions-llc) (proaxive.net)<br>The company provides IT consulting services to help clients align their business and processes with technology strategies in a digital-driven world | IT Services and IT Consulting | 🇺🇸 Irvine | 6 | 2018 |
| 28 | [Nakunj Inc](https://www.tamtam.ai/c/nakunj-inc) (nakunj.com)<br>Specializing in personalized Data Analytics and AI solutions to solve unique business problems, ensuring excellent ROI and competitive advantage for customers | Business Consulting and Services | 🇺🇸 Irvine | 4 | 2004 |
| 29 | [Scaleocity Works](https://www.tamtam.ai/c/scaleocity-works) (scaleocityworks.com)<br>This company provides full-service HR and workforce management solutions to help businesses navigate compliance, talent retention, and operational challenges for sustainable growth | Business Consulting and Services | 🇺🇸 Irvine | 3 | 2018 |
| 30 | [Priority Services Group Inc](https://www.tamtam.ai/c/priority-services-group-inc) (prioritysg.com)<br>Specializing in logistics and supply chain consulting, design, analysis, and contract management from manufacturing to distribution, with expertise in implementation and training | Transportation, Logistics, Supply Chain and Storage | 🇺🇸 Irvine | 2 | 2000 |

## 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.

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Source: https://www.tamtam.ai/l/consulting-firms-irvine