Company lists · Data refreshed September 2026
Top 25 Private investigation firms worldwide
RevenueBase identified 3,968 private investigation firms worldwide as of September 2026 and tracks 23,798 professional contacts across them, including 4,071 with verified work emails. The United States is the largest market and London the largest hub.
This list covers private investigation firms worldwide, 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. Country and city lists for private investigation firms follow the table.
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 private investigation firms worldwide
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 677 contacts → | ||||
Partial 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 20, 2026Thanks. The Data Team will review it. | |||||
| 2 | 572 contacts → | ||||
Partial evidence “DK Security is unique in that it offers a single company for a wide ranging availability of security and investigative services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 3 | 518 contacts → | ||||
Partial evidence “CoventBridge Group is the leading worldwide full service investigation solutions company providing: Surveillance, SIU and Compliance, Claims Investigation, Counter-Fraud Programs…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 4 | 336 contacts → | ||||
Partial 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 20, 2026Thanks. The Data Team will review it. | |||||
| 5 | 327 contacts → | ||||
Strong evidence “DigiStream Investigations is a full-service private investigation firm specializing in insurance defense and legal support services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 6 | 292 contacts → | ||||
Partial evidence “HUB Enterprises is a national insurance defense investigative firm.” Source: RevenueBase Database · checked Sep 20, 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 20, 2026Thanks. The Data Team will review it. | |||||
| 8 | 214 contacts → | ||||
Partial evidence “Advantage Investigations is a nationwide leader in the industry for investigative services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 9 | 163 contacts → | ||||
Indirect evidence “Globe Detective Agency (P) Ltd.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 10 | 146 contacts → | ||||
Partial 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 20, 2026Thanks. The Data Team will review it. | |||||
| 11 | 140 contacts → | ||||
Partial evidence “Corporate Research and Investigations Limited is a global provider of investigative research, background screening and business due diligence services for the world’s leading…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 12 | 129 contacts → | ||||
Strong evidence “Beau Dietl & Associates is a premier private investigation firm based in New York City with offices in New Jersey, Florida, and California.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 13 | 120 contacts → | ||||
Partial evidence “SERIS AIRPORT is a security and investigations company based out of 6 RUE DU GENERAL DE LARMINAT, PARIS, France.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 14 | 119 contacts → | ||||
Partial evidence “Knowledge is power" Whether you are an insurance company, TPA, insurance defense law firm, risk manager, private law firm, or corporation / business owner, we at Lemieux &…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 15 | 117 contacts → | ||||
Partial evidence “FACT are at the forefront of investigative and intelligence services, recognised by organisations, law enforcement, and governments worldwide.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 16 | 112 contacts → | ||||
Indirect evidence Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 17 | 107 contacts → | ||||
Partial 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 20, 2026Thanks. The Data Team will review it. | |||||
| 18 | 104 contacts → | ||||
Partial 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 20, 2026Thanks. The Data Team will review it. | |||||
| 19 | 94 contacts → | ||||
Indirect evidence “Why Becker & Company?” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 20 | 84 contacts → | ||||
Partial evidence “Marshall Investigative Group, division of Sphere Investigations, is a recognized leader in fraud and corporate investigations with more than 30 years of experience across North…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 21 | 84 contacts → | ||||
Partial evidence “Horsemen Investigations is a full service investigation company, specializing in investigating insurance fraud and in minimizing risk exposure.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 22 | 83 contacts → | ||||
Partial evidence “With a history dating back to 1979, Risk & Security Management is Australia’s leading provider of mercantile and investigation services.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 23 | 82 contacts → | ||||
Partial evidence “AJ Squared Security, Inc.(AJ2), is a privately owned security organization founded in May 2003 and incorporated in November 2003.” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 24 | 81 contacts → | ||||
Indirect evidence “Somos uma empresa de Investigação e Inteligência Corporativa conhecida nacionalmente por seus resultados em Recuperação de Veículos, Consultas Anti-fraude, Monitoramento Veicular…” Source: RevenueBase Database · checked Sep 20, 2026Thanks. The Data Team will review it. | |||||
| 25 | 72 contacts → | ||||
Indirect evidence “Integrated Security Services, Inc.” 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: private investigation 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 private investigation firms.
- Partial evidence
- Its own public description names part of private investigation firms, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name private investigation 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.
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Private investigation firms worldwide at a glance
As of Sep 20, 2026Companies by employee count
Email recency is reported on each country list linked below.
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 private investigation 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.
- Coverage
- Every country. Country and city lists for private investigation firms are linked below.
- What qualifies
- Companies worldwide whose own description of what they do matches “private investigation 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 private investigation 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 private investigation firms, and records with no verified work email.
- 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, 4,071 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.
Private investigation firms by location
11 lists · largest firstEvery Private investigation firms list RevenueBase publishes, by country and city. Counts are matching companies in each list as of its own refresh date.
Countries
- Private investigation firms based in the United States1,920
- Private investigation firms based in Italy209
- Private investigation firms based in the United Kingdom203
- Private investigation firms based in Canada133
- Private investigation firms based in Spain116
- Private investigation firms based in Australia89
- Private investigation firms based in the Netherlands51
Cities
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 private investigation 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 private investigation firms are there worldwide?
RevenueBase identified 3,968 private investigation firms worldwide 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 country has the most private investigation firms?
The United States leads with 1,920 companies, followed by Italy (209) and the United Kingdom (203). Every private investigation firms list by country and city is linked on this page.
Which city has the most private investigation firms?
London leads with 65 headquartered companies, followed by New York (62) and New Delhi (39).
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 4,071 verified decision-maker contacts tracked across these 3,968 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.