Company lists · Data refreshed September 2026
Top 12 Security contractors based in San Francisco, United States
RevenueBase identified 29 security contractors headquartered in San Francisco, United States as of September 2026 and tracks 628 professional contacts across them, including 67 with verified work emails. New York is the largest hub.
This list covers security contractors headquartered in San Francisco, 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 21, 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 12 largest security contractors based in San Francisco, United States
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 218 contacts → | ||||
Partial evidence “At ProGuard Security Services, we are unwavering in our commitment to achieving 100% accuracy through operational execution.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 2 | 34 contacts → | ||||
Indirect evidence “Global Secure 3 (GS3) is an international firm that provides risk management and investigation services to corporate and public sector organizations.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 3 | 32 contacts → | ||||
Indirect evidence “Everyone deserves to feel safe.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 4 | 27 contacts → | ||||
Partial evidence “Treeline Security combines the personal touch of a small, client-focused team, with the extensive reach and resources of a large network.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 5 | 13 contacts → | ||||
Partial evidence “CORE1 is one of the fastest growing security guard companies in the Northern California Bay Area providing Uniformed, Unarmed & Armed Security Officers, including Site Management…” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 6 | 12 contacts → | ||||
Partial evidence “Shield Corps Security is a private security firm dedicated to hiring military veterans.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 7 | 12 contacts → | ||||
Partial evidence “Our founder came to the USA as a mathematics student, and began his career as a security guard to support his education.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 8 | 9 contacts → | ||||
Partial evidence “The fundamental goal of CSS is to be an outstanding security organization dedicated to serving the Clients of CSS and the Public’s Safety, through its Officers, with effectiveness…” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 9 | 5 contacts → | ||||
Partial evidence “Nob Hill Security provides professional, reliable on-site security guard services throughout San Francisco, the Bay Area, and Northern California.” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 10 | 3 contacts → | ||||
Partial evidence “1 Cerberus Security & Patrol is a licensed company founded on the principles of professionalism and excellence of service!” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 11 | 2 contacts → | ||||
Partial evidence “Specializes in providing private security services for businesses, high end residences, government agencies, commercial complexes, home owner management services, & other public &…” Source: RevenueBase Database · checked Sep 21, 2026Thanks. The Data Team will review it. | |||||
| 12 | 1 contacts → | ||||
Partial evidence “Asymmetric is a security advisory firm headquartered in San Francisco, serving clients nationwide.” Source: RevenueBase Database · checked Sep 21, 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: security contractors. 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 security contractors.
- Partial evidence
- Its own public description names part of security contractors, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name security contractors. 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 12 of 29 security contractors based in San Francisco, United States
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Security contractors based in San Francisco, United States at a glance
As of Sep 21, 2026Companies by employee count
Email recency for this list is measured across the whole United States list rather than for San Francisco, so it is reported there. Company counts and contact totals on this page are exact for San Francisco, over 29 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 contractors, 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 San Francisco, United States whose own description of what they do matches “security contractors”. 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 security contractors), 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 security contractors, and records with no verified work email. Companies headquartered outside San Francisco 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, 67 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 21, 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.
Security contractors by metro in the United States
- Security contractors in New York163
- Security contractors in Los Angeles142
- Security contractors in Houston128
- Security contractors in Miami99
- Security contractors in Chicago73
- Security contractors in Atlanta66
- Security contractors in Dallas66
- Security contractors in Austin58
- Security contractors in Phoenix54
- Security contractors in Las Vegas52
- Security contractors in Orlando42
- Security contractors in Denver41
- Security contractors in Tampa41
- Security contractors in San Diego37
- Security contractors in San Antonio36
- Security contractors in Baltimore32
- Security contractors in Washington32
- Security contractors in Charlotte30
- Security contractors in Sacramento30
- Security contractors in San Francisco29
- Security contractors in Nashville28
- Security contractors in San Jose28
- Security contractors in Seattle27
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 security contractors, 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 security contractors are there based in San Francisco, United States?
RevenueBase identified 29 security contractors headquartered in San Francisco, 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?
Proguard Security Services, headquartered in San Francisco, tops this list with the largest team on record.
Which city has the most security contractors?
New York leads with 163 headquartered companies, followed by Los Angeles (142) and Houston (128).
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 67 verified decision-maker contacts tracked across these 29 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 21, 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.
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