Company lists · Data refreshed September 2026

Top 21 Security monitoring service providers based in New York, United States

RevenueBase identified 71 security monitoring service providers headquartered in New York, United States as of September 2026 and tracks 3,577 professional contacts across them, including 455 with verified work emails. New York is the largest hub.

This list covers security monitoring service providers headquartered in New York, 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 6, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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 Match evidence on every row Refreshed Sep 6, 2026 86% judged on-target in blind review
71Companies
3,577Contacts tracked
455Verified emails
Explore all 71 companies → Free signup · no credit card · 500 free credits

The 21 largest security monitoring service providers based in New York, United States

Ranked by team size
Top 21 of 71 security monitoring service providers based in New York, United States, ranked by team size, largest first. Data refreshed Sep 6, 2026. Evidence rates how directly each company's own description names security monitoring service providers: 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.
#CompanyHeadquartersEmployeesContacts
1
GuardsmarkPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202610001+1,375

“Guardsmark, LLC provides security services.”

Source: company website · checked Sep 6, 2026
2
MSA SecurityIndirect evidence
New York, NY, United StatesHQ checked Sep 6, 202610001+571

“Allied Universal Enhanced Protection Services delivers unrivaled threat mitigation expertise for government and business entities worldwide.”

Source: company website · checked Sep 6, 2026
3
DGA SecurityPartial evidence
New York, NY, United StatesHQ checked Sep 6, 2026201-500206

“Since 1969, thousands of businesses across the country have entrusted their protection to DGA Security.”

Source: company website · checked Sep 6, 2026
4
SilversealPartial evidence
New York, NY, United StatesHQ checked Sep 6, 2026501-1,000159

“Silverseal is a comprehensive security solutions firm with worldwide affiliations that can provide global security services in a highly professional manner.”

Source: company website · checked Sep 6, 2026
5New York, NY, United StatesHQ checked Sep 6, 2026501-1,000120

“Excel Security Corp.”

Source: company website · checked Sep 6, 2026
6
Gmsc SecurityPartial evidence
New York, United StatesHQ checked Sep 6, 2026501-1,00082

“For over 30 years GMSC has been securing high profile buildings and offices across New York and Chicago.”

Source: company website · checked Sep 6, 2026
7
Security USA INCPartial evidence
New York, NY, United StatesHQ checked Sep 6, 20261,001-5,00082

Security USA®, Inc.”

Source: company website · checked Sep 6, 2026
8
ADR SecurityPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202611-5072

“ADR Security is the leading provider of electronic and physical security services to some of New York's largest residential real estate portfolios.”

Source: company website · checked Sep 6, 2026
9
Global OPSPartial evidence
New York, NY, United StatesHQ checked Sep 6, 2026201-50070

“At GLOBAL OPS, we specialize in creating and implementing tailored security solutions that cater to the unique needs of our diverse clientele.”

Source: company website · checked Sep 6, 2026
10
A&h Security ServicesPartial evidence
New York, NY, United StatesHQ checked Sep 6, 20261,001-5,00060

“A&H Security Services, is a certified NYC MBE security services provider who makes a difference in our community.”

Source: company website · checked Sep 6, 2026
11
Port53Partial evidence
New York, NY, United StatesHQ checked Sep 6, 202651-20055

“Port53 Technologies is The Global Leader in Cisco-Based Managed Security Operations, helping organizations modernize and secure their digital environments through advanced…”

Source: company website · checked Sep 6, 2026
12
Securewatch 24Partial evidence
New York, NY, United StatesHQ checked Sep 6, 202611-5053

“SW24 is a privately-held, premier systems integration company founded by veteran law enforcement professionals and staffed by security industry experts.”

Source: company website · checked Sep 6, 2026
13
OHZ Remote GuardingIndirect evidence
New York, NY, United StatesHQ checked Sep 6, 202651-20036

“OHZ is America’s way to secure and save.”

Source: company website · checked Sep 6, 2026
14
Monitex SecurityPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202651-20035

“Your property secured 24/7 Our services: Construction Site Monitoring: Use real time, Live video surveillance to Prevent property damage, equipment theft, and injury liability…”

Source: company website · checked Sep 6, 2026
15
Target Security SystemsPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202611-5023

“Target Security Systems, LLC is New York City’s leading provider of cutting edge, high security solutions customized for today’s business and private sectors.”

Source: company website · checked Sep 6, 2026
16
Lead Security Group INCPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202651-20019

“Professional security solutions and protective firm, providing armed & unarmed security services, security patrols and executive Protection services for individuals, residential…”

Source: company website · checked Sep 6, 2026
17
Vertex Security SystemsPartial evidence
New York, NY, United StatesHQ checked Sep 6, 202611-5018

“We help busy organizations provide maximum security with simple but sophisticated solutions which enable them to have everything under control.”

Source: company website · checked Sep 6, 2026
18
Sight Watch SecurityStrong evidence
New York, United StatesHQ checked Sep 6, 20261-1013

“At SightWatch Security, we deliver proactive and trusted security solutions-from perimeter assessments to camera installation and real-time 24/7 monitoring.”

Source: company website · checked Sep 6, 2026
19
CyberconvoyIndirect evidence
New York, United StatesHQ checked Sep 6, 202611-5012

“We’re the nemesis of evil hackers attempting to take control of your system so they can extort money.”

Source: company website · checked Sep 6, 2026
20
BastionxIndirect evidence
New York, NY, United StatesHQ checked Sep 6, 202611-509

“At BastionX, we revolutionize how businesses harness technology.”

Source: company website · checked Sep 6, 2026
21
City Smart SystemsPartial evidence
New York, NY, United StatesHQ checked Sep 6, 20261-106

“Professional Security Contractors in Commercial and Residential Smart Home Automation, IP Cameras, Access Control, Network, Voice & Data”

Source: company website · checked Sep 6, 2026

Showing 21 of 71 security monitoring service providers based in New York, United States

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Security monitoring service providers based in New York, United States at a glance

As of Sep 6, 2026
11-50Median size (employees)
New YorkLargest hub · 71 HQs
Contacts with mobile numbers
Sep 6, 2026Data refreshed

Companies by employee count

1-10
16
11-50
25
51-200
14
201-500
4
501-1,000
6
1,001-5,000
3
10001+
2

Email recency for this list is measured across the whole United States list rather than this city, so it is reported there. Company counts and contact totals on this page are exact for New York, over 71 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 security monitoring service providers, 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: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
What qualifies
Companies headquartered in New York, United States whose own description of what they do matches “security monitoring service providers”. 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 security monitoring service providers, and records with no verified work email. Companies headquartered outside New York 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. 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, 455 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 6, 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 security monitoring service providers are there based in New York, United States?

RevenueBase identified 71 security monitoring service providers headquartered in New York, 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?

Guardsmark, headquartered in New York, tops this list with the largest team on record.

Which city has the most security monitoring service providers?

New York leads with 71 headquartered companies, followed by Houston (65) and Los Angeles (55).

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 455 verified decision-maker contacts tracked across these 71 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 6, 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 SmartSearch, 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.