As of my last update in January 2022, here's a list of some notable US IT recruiter companies:

1. Robert Half Technology: A division of Robert Half International, specializing in IT staffing and recruitment.

2. TEKsystems: A subsidiary of Allegis Group, TEKsystems is one of the largest IT staffing and services firms in the United States.

3. Kforce: Kforce provides staffing solutions and IT services to a wide range of industries, including technology, finance, healthcare, and government.

4. Randstad Technologies: Part of the Randstad Group, Randstad Technologies offers IT staffing and consulting services to clients across various industries.

5. CyberCoders: Specializing in technology recruitment, CyberCoders connects IT professionals with job opportunities in various sectors.

6. Aerotek: A leading provider of technical, professional, and industrial staffing services, Aerotek serves clients in the IT industry and beyond.

7. Apex Systems: A division of ASGN Incorporated, Apex Systems offers IT staffing and consulting services, focusing on contract, contract-to-hire, and permanent placements.

8. Insight Global: Insight Global provides IT staffing and managed services to clients in industries such as technology, healthcare, finance, and government.

9. SNI Technology: SNI Technology specializes in the recruitment and placement of IT professionals across a wide range of industries and job functions.

10. Modis: Modis offers IT staffing and consulting services, helping clients find top talent for project-based, contract, and permanent positions.

11. Diverse Lynx: Diverse Lynx provides IT staffing and consulting services to clients in various industries, including healthcare, finance, retail, and technology.

12. Strategic Staffing Solutions (S3): S3 is a global IT staffing and consulting firm, serving clients in North America and Europe.

13. Global Technical Talent (GTT): GTT offers IT staffing solutions, including contract, contract-to-hire, and permanent placements, across a wide range of industries.

14. Vaco: Vaco provides IT staffing and consulting services, focusing on delivering talent solutions tailored to clients' specific needs.

15. Collabera: Collabera offers IT staffing, consulting, and managed services to clients worldwide, with a focus on technology-driven industries.

Please note that the landscape of IT recruiting companies is vast and continually evolving. It's advisable to research each company further to determine their specialties, areas of expertise, and reputation before engaging with them. Additionally, new companies may emerge, and existing ones may undergo changes, so staying updated on industry developments is essential.