Company lists · Data refreshed September 2026

Top 25 Mission critical systems security companies based in Chicago, United States

Name: Mission critical systems security companies based in Chicago, United States
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 28, 2026 77 companies tracked

RevenueBase identified 77 mission critical systems security companies headquartered in Chicago, United States as of September 2026 and tracks 2,644 professional contacts across them, including 1,313 with verified work emails. Across the United States, New York is the largest hub for this category (123 companies); Chicago has 77.

This list covers mission critical systems security companies headquartered in Chicago, 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 28, 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.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 28, 2026 86% judged on-target in blind review

77Companies

2,644Contacts tracked

1,313Verified emails

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The 25 largest mission critical systems security companies based in Chicago, United States

Ranked by team size

Top 25 of 77 mission critical systems security companies based in Chicago, United States, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to mission critical systems security companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Coalfire	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1,001-5,000	947 contacts →
	Indirect evidence “Coalfire is the premier Cybersecurity and Compliance Services leader for the tech, healthcare, and finance industries.(This page is maintained by Marketing.” Source: RevenueBase Database · checked Sep 28, 2026
2	Trustwave, A Levelblue Company	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	501-1,000	874 contacts →
	Indirect evidence “Trustwave, a LevelBlue Company, is a globally recognized cybersecurity leader that reduces cyber risk and fortifies organizations against disruptive and damaging cyber threats.” Source: RevenueBase Database · checked Sep 28, 2026
3	Evolve Security Academy	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	n/a	166 contacts →
	Partial evidence “Evolve Security is a technical cybersecurity firm and the home of Evolve Academy, offering holistic and advanced cybersecurity training and continuously ranked #1 in the U.S.” Source: RevenueBase Database · checked Sep 28, 2026
4	Crossrealms International	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	88 contacts →
	Indirect evidence “CrossRealms International is a Cybersecurity-First company operating across the United States, Europe, MENA region, and Asia.” Source: RevenueBase Database · checked Sep 28, 2026
5	Entara	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	69 contacts →
	Partial evidence “Experiencing a security incident?” Source: RevenueBase Database · checked Sep 28, 2026
6	NCC Group North America	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1,001-5,000	50 contacts →
	Partial evidence “Founded in we are NCC Group plc, a global leader in cyber security and business resilience.” Source: RevenueBase Database · checked Sep 28, 2026
7	MIS Computer MSP	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	40 contacts →
	Indirect evidence “MIS Computer: More Than An MSP.” Source: RevenueBase Database · checked Sep 28, 2026
8	Securion	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	29 contacts →
	Partial evidence “SECURION was formed by industry problem-solving veterans that came together to bring their vision of a completely security focused, vendor agnostic, secure by design approach.” Source: RevenueBase Database · checked Sep 28, 2026
9	Abira Security	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	27 contacts →
	Partial evidence “In today’s digitally connected world, cyber security plays a crucial role.” Source: RevenueBase Database · checked Sep 28, 2026
10	Ravenswood Technology Group	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	21 contacts →
	Indirect evidence “At Ravenswood Technology Group, we don’t just offer our customers cybersecurity solutions – we deliver value and expertise you can rely on as needs and risks change.” Source: RevenueBase Database · checked Sep 28, 2026
11	Impelix	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	10 contacts →
	Partial evidence “Cyber threats are relentless, and security teams are overwhelmed.” Source: RevenueBase Database · checked Sep 28, 2026
12	Arxnimbus	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	10 contacts →
	Indirect evidence “ArxNimbus brings visibility to every organization’s cybersecurity program, radically advancing how businesses understand and optimize for real resilience.” Source: RevenueBase Database · checked Sep 28, 2026
13	Hciss, LLC Bsecaenergy	Strong evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	10 contacts →
	Strong evidence “HCISS is an AI-Powered Cybersecurity company focused on helping organizations secure digital systems, sensitive data, and critical operations in an increasingly complex threat…” Source: RevenueBase Database · checked Sep 28, 2026
14	Harrington Technology & Associates, INC	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	9 contacts →
	Partial evidence “HTA Technology Security Consulting (HTA) is a certified Woman-Owned, Small, Disadvantaged, Minority business with offices in Chicago, IL, and the Washington DC corridor.” Source: RevenueBase Database · checked Sep 28, 2026
15	Data Defenders, LLC	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	9 contacts →
	Partial evidence “Data Defenders is at the forefront of Managed Cybersecurity Operations Providers (MCOP), specializing in safeguarding municipalities through our exclusive Regional Security…” Source: RevenueBase Database · checked Sep 28, 2026
16	Dataguard	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	8 contacts →
	Partial evidence “DataGuard Cybersecurity Without The Complexity DataGuard uses state-of-the-art industry resources to implement a multi-layer defense for each client’s unique cyber security needs.” Source: RevenueBase Database · checked Sep 28, 2026
17	Cyber Bark LLC	Indirect evidence	Chicago, United StatesHQ checked Sep 28, 2026	51-200	7 contacts →
	Indirect evidence “At Cyber Bark, we bring 100 years of collective experience to the table, serving businesses across the US from our base in Illinois.” Source: RevenueBase Database · checked Sep 28, 2026
18	Amol Solutions	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1-10	7 contacts →
	Indirect evidence “Amol Solutions strives to be a leader in cybersecurity services for organizations of all sizes.” Source: RevenueBase Database · checked Sep 28, 2026
19	Clairos	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	51-200	6 contacts →
	Partial evidence “Clairos is a cybersecurity company that helps organizations build stronger, more manageable security programs through a practical, tailored approach.” Source: RevenueBase Database · checked Sep 28, 2026
20	Hellfire Security	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	6 contacts →
	Indirect evidence “Not auditors but real hackers.” Source: RevenueBase Database · checked Sep 28, 2026
21	Network Aegis	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1-10	5 contacts →
	Indirect evidence “Welcome to Network Aegis!” Source: RevenueBase Database · checked Sep 28, 2026
22	Teamwerks	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	5 contacts →
	Indirect evidence “TeamWerks is an IT company based in the United States.” Source: RevenueBase Database · checked Sep 28, 2026
23	Clear Loss Prevention, INC	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	4 contacts →
	Partial evidence “ClearLP is a woman owned business specializing in digital security and network technology.” Source: RevenueBase Database · checked Sep 28, 2026
24	Cyber Pop-Up	Indirect evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	1-10	4 contacts →
	Indirect evidence “Cybersecurity for small businesses.” Source: RevenueBase Database · checked Sep 28, 2026
25	Urbane Security	Partial evidence	Chicago, IL, United StatesHQ checked Sep 28, 2026	11-50	4 contacts →
	Partial evidence “Urbane Security is an information security firm that provides specially tailored security and compliance solutions that empower the Fortune 500 to securely focus on their ultimate…” Source: RevenueBase Database · checked Sep 28, 2026

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: mission critical systems security companies. 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 mission critical systems security companies.
Partial evidence: Its own public description names part of mission critical systems security companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name mission critical systems security companies. 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 77 mission critical systems security companies based in Chicago, United States

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Mission critical systems security companies based in Chicago, United States at a glance

As of Sep 28, 2026

49.7%Verified-email coverage

34.3Average contacts per company

11-50Median size (employees)

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

11-50

51-200

201-500

501-1,000

1,001-5,000

Email recency for this list is measured across the whole United States list rather than for Chicago, so it is reported there. Company counts and contact totals on this page are exact for Chicago, over 77 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 mission critical systems security companies, 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 Chicago, United States whose own description of what they do matches “mission critical systems security companies”. 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 mission critical systems security companies), 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 mission critical systems security companies, and records with no verified work email. Companies headquartered outside Chicago 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, 1,313 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 28, 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.

Mission critical systems security companies by metro in the United States

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 mission critical systems security companies, 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 mission critical systems security companies are there based in Chicago, United States?

RevenueBase identified 77 mission critical systems security companies headquartered in Chicago, 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?

Coalfire, headquartered in Chicago, tops this list with the largest team on record.

Which city in the United States has the most mission critical systems security companies?

New York leads the United States with 123 headquartered companies, followed by Washington (100) and Houston (89). Chicago has 77.

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 1,313 verified decision-maker contacts tracked across these 77 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 28, 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.