Company lists · Data refreshed September 2026

Top 25 Cybersecurity defense companies based in the United States

Name: Cybersecurity defense companies based in the United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 1, 2026 4,902 companies tracked

There are 4,902 cybersecurity defense companies headquartered in the United States (RevenueBase, September 2026). RevenueBase tracks 153,560 professional contacts across them, including 48,377 with verified work emails and 52,807 with mobile numbers. New York is the largest hub.

This list covers cybersecurity defense companies 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, how directly it supports the match, and when it was last checked. Data refreshed September 1, 2026.

4,902Companies

153,560Contacts tracked

48,377Verified emails

52,807Mobile numbers

Unlock all 4,902 companies Free account · no credit card · 2 minutes

The 25 largest cybersecurity defense companies based in the United States

Ranked by team size

Top 25 of 4,902 cybersecurity defense companies based in the United States, ranked by team size, largest first. Data refreshed Sep 1, 2026. Evidence rates how directly each company's own description names cybersecurity defense companies: strong (names it), partial (names part of it), indirect (matched on its full profile rather than the summary shown). Click a count to unlock that company's people.
#	Company	Headquarters	Employees	Contacts	Verified emails
1	L3harris TechnologiesPartial evidence “L3Harris Technologies is the Trusted Disruptor in the defense industry.” Source: company website · checked Sep 1, 2026	Melbourne, FL, United States	10001+	24,757	932
2	SymantecPartial evidence “Your backstage pass to the most epic cybersecurity solutions on the market for Endpoint, Network, Data and Cloud security.” Source: company website · checked Sep 1, 2026	San Jose, CA, United States	10001+	11,179	876
3	TrellixPartial evidence “Trellix is a global cybersecurity company delivering intelligence-led cyber resilience for security-conscious organizations at any stage of their journey.” Source: company website · checked Sep 1, 2026	Plano, TX, United States	1,001-5,000	3,490	1,633
4	SentinelonePartial evidence “SentinelOne is the world's leading AI-powered cybersecurity platform.” Source: company website · checked Sep 1, 2026	Mountain View, CA, United States	1,001-5,000	3,046	1,926
5	OPTIVIndirect evidence “Optiv is the cyber advisory and solutions leader, delivering strategic and technical expertise to nearly companies across every major industry.” Source: company website · checked Sep 1, 2026	Chantilly, VA, United States	1,001-5,000	2,206	1,422
6	BitdefenderPartial evidence “Bitdefender is a cybersecurity leader delivering best-in-class threat prevention, detection, and response solutions worldwide.” Source: company website · checked Sep 1, 2026	Fort Lauderdale, FL, United States	1,001-5,000	2,141	1,230
7	BarracudaPartial evidence “Barracuda is a leading global cybersecurity company providing complete protection against complex threats for all size business.” Source: company website · checked Sep 1, 2026	Alpharetta, GA, United States	1,001-5,000	2,108	1,463
8	FortraPartial evidence “Fortra delivers AI-amplified cybersecurity solutions that help organizations use and protect data with confidence.” Source: company website · checked Sep 1, 2026	Eden Prairie, MN, United States	1,001-5,000	1,640	1,037
9	Thales Cybersecurity ProductsPartial evidence “Thales is a global leader in cybersecurity, helping the most trusted organizations in the world protect their most critical applications, data, and identities anywhere at scale.” Source: company website · checked Sep 1, 2026	Austin, TX, United States	1,001-5,000	1,252	645
10	Guidepoint SecurityPartial evidence “GuidePoint Security provides trusted cybersecurity expertise, solutions, and services that help organizations make informed decisions and minimize risk.” Source: company website · checked Sep 1, 2026	Tampa, FL, United States	1,001-5,000	1,234	809
11	ImpervaIndirect evidence “On Dec.” Source: company website · checked Sep 1, 2026	Austin, TX, United States	10001+	1,211	829
12	Watchguard TechnologiesIndirect evidence “WatchGuard® Technologies, Inc.” Source: company website · checked Sep 1, 2026	Seattle, WA, United States	1,001-5,000	1,054	631
13	CoalfirePartial evidence “Coalfire is the premier Cybersecurity and Compliance Services leader for the tech, healthcare, and finance industries.(This page is maintained by Marketing.” Source: company website · checked Sep 1, 2026	Chicago, IL, United States	1,001-5,000	960	613
14	NetenrichIndirect evidence “Netenrich is redefining security operations by shifting the focus from "efficiency"(speed) to "efficacy"(comprehensive coverage).” Source: company website · checked Sep 1, 2026	San Jose, CA, United States	501-1,000	885	261
15	Absolute SecurityIndirect evidence “Absolute Security is partnered with more than 28 of the world’s leading endpoint device manufacturers, embedded in the firmware of 600 million devices, trusted by global…” Source: company website · checked Sep 1, 2026	Seattle, WA, United States	501-1,000	789	449
16	STRIndirect evidence “STR is driven to deliver impact.” Source: company website · checked Sep 1, 2026	Arlington, VA, United States	501-1,000	759	24
17	ThreatlockerIndirect evidence “The ThreatLocker® story.” Source: company website · checked Sep 1, 2026	Orlando, FL, United States	501-1,000	725	406
18	HuntressIndirect evidence “Protect Your Endpoints, Identities, Logs, and Employees.” Source: company website · checked Sep 1, 2026	Columbia, MD, United States	501-1,000	694	135
19	Telos CorporationIndirect evidence “Telos empowers and protects the world’s most security-conscious organizations with solutions for continuous security assurance of individuals, systems, and information.” Source: company website · checked Sep 1, 2026	Las Vegas, NV, United States	501-1,000	636	230
20	VikingcloudPartial evidence “VikingCloud delivers battle-tested cybersecurity and compliance solutions that simply work.” Source: company website · checked Sep 1, 2026	Chicago, IL, United States	1,001-5,000	618	436
21	Ultraviolet CyberIndirect evidence “UltraViolet Cyber is the only security operations partner that unifies red, blue, and purple team capabilities into one integrated program.” Source: company website · checked Sep 1, 2026	Phoenix, AZ, United States	501-1,000	517	258
22	SecurityhqPartial evidence “SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Source: company website · checked Sep 1, 2026	New York, NY, United States	501-1,000	492	279
23	CyberproofIndirect evidence “CyberProof delivers threat-led (via Continuous Threat Exposure Management), co-managed security operations with the belief that better security is achieved through the right…” Source: company website · checked Sep 1, 2026	Aliso Viejo, CA, United States	501-1,000	429	160
24	DUO SecurityIndirect evidence “We are Duo, and we’re here to democratize security.” Source: company website · checked Sep 1, 2026	Austin, TX, United States	501-1,000	429	21
25	United Security, Inc. USIIndirect evidence “United Security Inc.(USI) provides personalized security solutions enhanced by advanced technology and cyber services.” Source: company website · checked Sep 1, 2026	Boston, MA, United States	1,001-5,000	409	72

Showing 25 of 4,902 cybersecurity defense companies based in the United States

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Cybersecurity defense companies based in the United States at a glance

As of Sep 1, 2026

1-10Median size (employees)

New YorkLargest hub · 157 HQs

52,807Contacts with mobile numbers

Sep 1, 2026Data refreshed

Companies by employee count

1-10

2,580

11-50

1,597

51-200

498

201-500

110

501-1,000

1,001-5,000

10001+

Cybersecurity defense companies by metro

Metro	Companies
Cybersecurity defense companies in New York	157
Cybersecurity defense companies in Houston	92
Cybersecurity defense companies in Atlanta	91
Cybersecurity defense companies in Washington	90
Cybersecurity defense companies in Miami	84
Cybersecurity defense companies in Austin	84
Cybersecurity defense companies in Dallas	78

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 cybersecurity defense companies, so some rows will be adjacent to the category rather than pure plays. The description and evidence rating on every row are there so you can check each match yourself.

Source: The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
What qualifies: Companies headquartered in the United States whose own description of what they do matches “cybersecurity defense companies”. Matching reads each company's description, not its industry code or its name.
What we exclude: Companies whose own description does not clearly place them among cybersecurity defense companies, 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 an evidence rating so you can judge each match yourself.
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, 48,377 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 1, 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.

Frequently asked

How many cybersecurity defense companies are there based in the United States?

There are 4,902 cybersecurity defense companies headquartered in the United States as of September 2026 (RevenueBase).

What is the largest company on this list?

L3harris Technologies, headquartered in Melbourne, tops this list with the largest team on record.

Which city has the most cybersecurity defense companies?

New York leads with 157 headquartered companies, followed by Houston (92) and Atlanta (91).

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 48,377 verified decision-maker contacts tracked across these 4,902 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 1, 2026.

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 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, the same data that powers RevenueBase's B2B data products and the free research portal.