Senior Recruiter and People Operations
Sirenopt · San Leandro, California, United States · Posted Jul 6, 2026
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About SirenOpt
SirenOpt helps manufacturers make better, safer, and more reliable micro- and nano-materials. These materials are the building blocks of critical sectors of the global economy such as batteries, computer chips, aircraft components, and power systems. But, surging material demand and growing complexity are pushing production to unprecedented scales and speeds, leaving manufacturers effectively flying blind. Small, undetected variations during production lead to wastage, lower performance, higher costs, and safety risks.
SirenOpt is changing this. Our manufacturing intelligence platform scans materials, revealing critical internal information without damaging them. Using a novel combination of cold atmospheric plasma, physics-informed machine learning, and predictive analytics, SirenOpt creates unique, real-time fingerprints that capture material signals no other method can access. These insights give manufacturers unprecedented visibility into how materials behave as they are made.
We turn hidden data into actionable intelligence to help manufacturers reduce variability and thus increase yield and performance. The technology can be deployed as a standalone tool or integrated directly into factory production lines. SirenOpt is currently deploying early versions of its platform with some of the largest industrial manufacturers in the world across North America, Europe, and Asia. Our first commercial product will be released in 2026.
Role Overview
SirenOpt is looking for an experienced Senior Recruiter to help us build and scale a high-performing team while supporting core HR operations. As the first full-time recruiter on the SirenOpt team, you will own full-cycle recruiting while contributing to key HR processes such as onboarding, employee lifecycle support, and policy implementation. The ideal candidate is hands-on, strategic, and comfortable operating in a fast-paced startup environment with a high degree of ownership.
This role offers an exciting opportunity to shape our hiring strategy and HR infrastructure from the ground up while working closely with leadership and cross-functional teams throughout the organization.
What You’ll Do
Own full-cycle recruiting across technical and non-technical roles (sourcing, screening, coordinating interviews and on-site visits, and closing candidates)
Partner with hiring managers to define role requirements, interview processes, and hiring strategies
Build and maintain strong candidate pipelines for current and future critical roles
Manage and optimize the Applicant Tracking System (ATS) and recruiting workflows, ensuring an excellent candidate experience
Coordinate interviews, candidate communications, and offer processes
Identify when to engage external search firms for specialized or senior roles, and manage those relationships and associated search processes
Support onboarding and new hire orientation to ensure a smooth employee experience
Assist with HR operations including employee records, compliance, and policy administration
Help develop and document HR and recruiting processes, policies, and best practices
Contribute to employer branding efforts (careers page, LinkedIn presence, events, and referrals)
What We’re Looking For
Bachelor’s degree in Human Resources, Business Administration, or related field
8+ years of experience in recruiting, with exposure to HR responsibilities
Demonstrated experience owning recruiting across a wide variety of functions including both technical and non-technical roles
Proven ability to partner with leadership and hiring managers on workforce planning and hiring strategy
Familiarity with processes such as onboarding, compliance, and employee lifecycle support
Strong organizational and communication skills with attention to detail
Startup experience is strongly preferred, including a demonstrated ability to manage multiple priorities effectively in a fast-paced environment
Experience with ATS platforms (e.g., Greenhouse) and recruiting tools
Exposure to HRIS systems, payroll coordination, and benefits administration
Hands-on experience with HRIS, payroll coordination, and benefits administration; familiarity with Gusto is a strong plus
Why Join SirenOpt
Opportunity to make a direct impact in building a growing, mission-driven company
Work closely with leadership and influence hiring and HR strategy
Fast-paced, collaborative startup environment with high ownership
Exposure to cutting-edge technology in advanced manufacturing and AI
Base Pay Range
$110,000 $140,000 USD
Benefits
Equity and Salary compensation depends on experience
Health, Dental, Vision plans provided
401k matching provided
Time off: 20 days of PTO per year, plus approximately 15 paid US holidays per year