Company lists · Data refreshed September 2026
Top 25 Professional service firms based in the United States
RevenueBase identified 1,955 professional service firms headquartered in the United States as of September 2026 and tracks 82,192 professional contacts across them, including 42,791 with verified work emails. New York is the largest hub.
This list covers professional service firms headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 20, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.
The 25 largest professional service firms based in the United States
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 8,779 contacts → | ||||
Indirect evidence “Protiviti is a global consulting firm that delivers deep expertise, objective insights, a tailored approach and unparalleled collaboration to help leaders confidently face the…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 2 | 6,369 contacts → | ||||
Strong evidence “CBIZ, Inc.(NYSE: CBZ) is a leading professional services advisor to middle-market businesses nationwide.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 3 | 4,199 contacts → | ||||
Indirect evidence “EisnerAmper, one of the largest business consulting firms in the world, is comprised of EisnerAmper LLP, a licensed independent CPA firm that provides client attest services; and…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 4 | 3,047 contacts → | ||||
Indirect evidence “Always advancing.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 5 | 2,996 contacts → | ||||
Strong evidence “Citrin Cooperman is one of the nation’s largest and fastest-growing professional services firms.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 6 | 2,102 contacts → | ||||
Indirect evidence “Carr, Riggs & Ingram (CRI) is a Top 25 nationally-ranked accounting and advisory firm driven by relationships to cultivate growth.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 7 | 2,035 contacts → | ||||
Strong evidence “UHY is one of the nation’s largest professional services firms providing audit, tax, consulting and advisory services to clients primarily in the dynamic middle market.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 8 | 1,688 contacts → | ||||
Strong evidence “Sikich offers the public and private sectors a diverse platform of professional services across consulting, technology, and compliance.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 9 | 1,323 contacts → | ||||
Strong evidence “Rehmann is a professional advisory firm that provides accounting and assurance, business solutions and outsourcing, specialized consulting, and wealth management services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 10 | 1,056 contacts → | ||||
Indirect evidence “RubinBrown provides unmatched service to closely held and publicly traded companies in specialized market sectors as well as non-profit and public sector organizations.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 11 | 844 contacts → | ||||
Indirect evidence “Warren Averett CPAs and Advisors is a top-tier accounting and advisory firm based in the Southeastern U.S, proudly ranking among the nation's top 50 firms.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 12 | 634 contacts → | ||||
Indirect evidence “At Blue & Co.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 13 | 496 contacts → | ||||
Strong evidence “Providing Professional Business Advisory and Consulting Services including tax, accounting and IT services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 14 | 487 contacts → | ||||
Indirect evidence “SingerLewak has a 60-year history of serving clients as one of the leading West Coast based public accounting firms; SingerLewak understands the needs of business owners and…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 15 | 467 contacts → | ||||
Indirect evidence “Prager Metis CPAs is an independent, full service, public accounting and consulting firm.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 16 | 413 contacts → | ||||
Indirect evidence “Smith + Howard is a tax, accounting, advisory, and consulting firm headquartered in Atlanta, with a global presence.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 17 | 393 contacts → | ||||
Indirect evidence “PBMares is a Certified Public Accounting and consulting firm focused on serving the audit, tax, accounting, and consulting needs of companies and individuals.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 18 | 392 contacts → | ||||
Indirect evidence “Since 1953, REDW Advisors & CPAs has been fully committed to the success of our clients.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 19 | 376 contacts → | ||||
Indirect evidence “We Are All About You That is why we take a holistic approach to assisting clients with growing, managing, and protecting their hard work.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 20 | 361 contacts → | ||||
Indirect evidence Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 21 | 354 contacts → | ||||
Strong evidence “Stevens & Lee is the cornerstone of The Stevens & Lee Companies, a platform of affiliated professional service firms which provides a full range of legal, investment banking…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 22 | 347 contacts → | ||||
Indirect evidence “Clark Nuber is an award-winning Certified Public Accounting firm located in the Seattle Metro Area.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 23 | 323 contacts → | ||||
Strong evidence “Listed below are the two entities that make up SVA, a highly diversified, independent professional services firm.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 24 | 314 contacts → | ||||
Indirect evidence “Adams Brown, LLC, a leading CPA and advisory firm, has delivered value-added accounting and advisory services to businesses and their owners since 1945.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 25 | 300 contacts → | ||||
Indirect evidence “Service is the sole purpose of our existence.” -James “Jim” Moore We’ve lived by these words ever since our firm was founded in 1964.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
RevenueBase Smart Search
RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: professional service firms. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.
- Strong evidence
- The company's own public description of its business names professional service firms.
- Partial evidence
- Its own public description names part of professional service firms, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name professional service firms. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.
RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.
Showing 25 of 1,955 professional service firms based in the United States
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Professional service firms based in the United States at a glance
As of Sep 20, 2026Companies by employee count
Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 1,955 companies.
How this list was built
Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among professional service firms, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
- What qualifies
- Companies headquartered in the United States whose own description of what they do matches “professional service firms”. Matching reads each company's description, not its industry code or its name.
- RevenueBase Smart Search
- RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names professional service firms), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
- What we exclude
- Companies whose own description does not clearly place them among professional service firms, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
- Match quality
- In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
- Ranking
- Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
- Verification
- Every listed company carries at least one verified work email, 42,791 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
- Refresh
- This page's figures were pulled from the company graph on September 20, 2026. Lists refresh periodically as the graph is re-checked.
- Corrections
- Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.
Professional service firms by metro
Frequently asked
What is RevenueBase Smart Search?
RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names professional service firms, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.
How many professional service firms are there based in the United States?
RevenueBase identified 1,955 professional service firms headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.
What is the largest company on this list?
Protiviti, headquartered in Menlo Park, tops this list with the largest team on record.
Which city has the most professional service firms?
New York leads with 65 headquartered companies, followed by Atlanta (40) and Houston (36).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 42,791 verified decision-maker contacts tracked across these 1,955 companies.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 20, 2026.
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About this data
RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.
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