Company lists · Data refreshed September 2026
Top 25 Due diligence firms based in the United States
RevenueBase identified 777 due diligence firms headquartered in the United States as of September 2026 and tracks 10,656 professional contacts across them, including 3,489 with verified work emails. New York is the largest hub.
This list covers due diligence 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 19, 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 due diligence firms based in the United States
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 677 contacts → | ||||
Indirect evidence “OMNIPLEX World Services Corporation is a leader and innovator in delivering professional background investigations, intelligence support, and physical security services to…” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 2 | 667 contacts → | ||||
Indirect evidence “cFIRST is a digital global background screening service provider headquartered in Cincinnati, Ohio.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 3 | 336 contacts → | ||||
Indirect evidence “Vcheck is a global investigations firm that helps institutions protect their investments by providing intelligence on individuals and entities.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 4 | 308 contacts → | ||||
Indirect evidence “At Comply, we pride ourselves on being the champion for compliance professionals.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 5 | 268 contacts → | ||||
Indirect evidence “We stand at the forefront of leadership, insight, and guidance in a world marked by complexity and uncertainty.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 6 | 241 contacts → | ||||
Indirect evidence “We know you work hard to get the best deal possible.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 7 | 214 contacts → | ||||
Indirect evidence “Frasco has hundreds of investigators and regional offices located throughout the country.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 8 | 146 contacts → | ||||
Indirect evidence “A federally qualified Small Business, IDS offers end to end investigative solutions tailored to meet the specific needs of our clients.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 9 | 142 contacts → | ||||
Strong evidence “PSA is a global due diligence and investigations firm headquartered in Washington, DC.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 10 | 141 contacts → | ||||
Indirect evidence “TrendSource helps businesses document and measure compliance across employment, consumer reporting, government, finance, health care, and retail.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 11 | 137 contacts → | ||||
Indirect evidence “Vault Workforce Screening was acquired by Sterling on January 2, 2024.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 12 | 112 contacts → | ||||
Indirect evidence Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 13 | 107 contacts → | ||||
Strong evidence “Alias Intelligence is a leading background investigations and due diligence company delivering the information and insights our clients need to grow and navigate their businesses.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 14 | 104 contacts → | ||||
Indirect evidence “The Robison Group is an agency of professional investigators and support teams offering surveillance, SIU claims, business risk mitigation and comprehensive desktop investigation…” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 15 | 98 contacts → | ||||
Indirect evidence “Accume Partners, now part of Cherry Bekaert, is a trusted risk assurance and advisory leader and innovator in delivering integrated solutions to our clients in highly regulated…” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 16 | 96 contacts → | ||||
Indirect evidence “Gryphon partners with clients across the globe to help them assess new opportunities and tackle their most complex problems often in challenging and opaque markets.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 17 | 93 contacts → | ||||
Indirect evidence “Verified Credentials, LLC is a leading background screening company.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 18 | 93 contacts → | ||||
Indirect evidence “RosettiStarr provides cutting-edge intelligence, investigations, corporate risk and cyber security services to management teams, attorneys and investors worldwide.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 19 | 93 contacts → | ||||
Indirect evidence “ICS Merrill has joined forces with GlobalOptions to created CoventBridge Group, the largest worldwide investigative services company providing: Surveillance, SIU and Compliance…” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 20 | 85 contacts → | ||||
Indirect evidence “Hiring decisions are more complex than ever.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 21 | 77 contacts → | ||||
Strong evidence “CREtelligent’s Radius Platform is the world's first 24/7 "CRE Due Diligence Storefront." CREtelligent provides almost every due diligence service CRE buyers, lenders and sellers…” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 22 | 75 contacts → | ||||
Strong evidence “Blue Heron Research Partners is an international leader in qualitative due diligence.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 23 | 72 contacts → | ||||
Indirect evidence “Integrated Security Services, Inc.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 24 | 70 contacts → | ||||
Indirect evidence “A recognized leader in forensic and financial consulting for more than 60 years.” Source: RevenueBase Database · checked Sep 19, 2026Thanks. The Data Team will review it. | |||||
| 25 | 69 contacts → | ||||
Indirect evidence “CSI is a full-service investigative firm that delivers key facts to give our clients an actionable advantage in a wide range of situations.” Source: RevenueBase Database · checked Sep 19, 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: due diligence 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 due diligence firms.
- Partial evidence
- Its own public description names part of due diligence firms, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name due diligence 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 777 due diligence firms based in the United States
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Due diligence firms based in the United States at a glance
As of Sep 19, 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 777 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 due diligence 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 “due diligence 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 due diligence 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 due diligence 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, 3,489 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 19, 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.
Due diligence firms by metro
- Due diligence firms in New York50
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 due diligence 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 due diligence firms are there based in the United States?
RevenueBase identified 777 due diligence 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?
Omniplex World Services Corporation, headquartered in Herndon, tops this list with the largest team on record.
Which city has the most due diligence firms?
New York leads with 50 headquartered companies, followed by Washington (19) and Miami (18).
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 3,489 verified decision-maker contacts tracked across these 777 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 19, 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.