NAICS 561621:
Security Systems Services (except Locksmiths)
This U.S. industry comprises establishments primarily engaged in (1) selling security alarm systems, such as burglar and fire alarms, along with installation, repair, or monitoring services or (2) remote monitoring of electronic security alarm systems.
Fire alarm monitoring servicesAlarm system monitoring servicesBurglar alarm monitoring services+1 example
Security system monitoring services
Matching SIC code: 7382 Security Systems Services
Where it sits
- 56Administrative and Support and Waste Management and Remediation ServicesSector
- 561Administrative and Support ServicesSubsector
- 5616Investigation and Security ServicesIndustry group
- 56162Security Systems ServicesNAICS industry
- 561621Security Systems Services (except Locksmiths)National industry
Largest companies with NAICS 561621
Updated Nov 9, 2026| Rank | Company | Headquarters | Employees |
|---|---|---|---|
| 1 |  ADTadt.com | Boca Raton, US | 26K |
| 2 |  Vivintvivint.com | Lehi, US | 8.6K |
| 3 |  Securitas Technologysecuritastechnology.com | Uniontown, US | 4.6K |
| 4 |  Everoneveronsolutions.com | Irving, US | 2.6K |
| 5 |  STANLEY Securitystanleysecurity.com | Fishers, US | 2.3K |
| 6 |  Pavionpavion.com | Chantilly, US | 2.2K |
| 7 |  Pye-Barker Fire & Safetypyebarkerfs.com | Alpharetta, US | 2.2K |
| 8 |  Vector Securityvectorsecurity.com | Warrendale, US | 1.7K |
| 9 |  Flockflocksafety.com | Atlanta, US | 1.4K |
| 10 |  Safe Haven Security Services, LLC.mysafehaven.com | Kansas City, US | 1.4K |
Not this code?
Similar activities the Census classifies elsewhere.
- 42Wholesale TradeSelling security alarm systems for buildings, without installation, repair, or monitoring services
- 238210Electrical Contractors and Other Wiring Installation ContractorsInstalling alarm systems (e.g., fire, burglar), without selling or monitoring services
- 441330Automotive Parts and Accessories RetailersRetailing motor vehicle security systems, with or without installation or repair services
Questions about NAICS 561621
Which businesses use NAICS 561621?
Fire alarm monitoring services, alarm system monitoring services and burglar alarm monitoring services, and similar businesses in the Administrative and Support and Waste Management and Remediation Services sector. This U.S.
What SIC code matches NAICS 561621?
SIC 7382, Security Systems Services, from the US Census Bureau's concordance between the two systems.
How many companies have NAICS 561621?
8,837 companies with a website carry NAICS 561621 as their primary code in Crustdata's data, worldwide.
Find any company's NAICS codeType a company name or website and get its codes with their titles.
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Sign up freeCode titles, definitions, examples and SIC matches: NAICS 2022 and the Census concordances, US Census Bureau. Company counts and lists: Crustdata, companies with a website, each by its primary code, updated weekly. Employee counts are estimates.