About Antithesis

We've been quietly reinventing how the world thinks about software reliability, and we're just getting started! At Antithesis, we start at the foundations – we run entire software systems inside a deterministic simulation and break them in every way imaginable. Every issue then comes with a perfect reproduction, so you can identify root causes fast instead of spending days trying to recreate what went wrong.

The rise of AI-generated code has made this work more urgent than ever. Agents can write code faster than any human, but speed doesn't matter much when the output is buggy, stuck in review, or slipping through undetected. The verification bottleneck is real, it's growing, and solving it is one of the most consequential problems in software right now. That's what you'd be working on.

We're well-funded and deeply technical, the kind of place where the hardest problems get the most attention and the best ideas win regardless of who has them. If you want to do work that actually moves the needle on how reliable software can be, keep reading.

About This Role

Antithesis is growing fast, and the people experience behind that growth is one of the most critical steps in building a successful organization. We're looking for an People Ops Generalist who is also a genuine benefits expert. Someone who brings structure and warmth to onboarding and offboarding, knows open enrollment inside and out, and has a natural instinct for building the kind of culture people want to be part of.

This is a hands-on, mid-level role where you'll own critical people operations day to day. You'll be a trusted resource for employees across the company and a close partner to the VP of People. You're someone who doesn't wait to be asked, who sees a gap and fills it, and who takes real pride in making the employee experience feel effortless. This is a fun but demanding role

What You'll Do

Onboarding & Offboarding

• Own the full onboarding experience from offer acceptance to day-one readiness, including Rippling setup, equipment coordination, paperwork, and welcome communications.

• Design and continuously improve a structured new hire program that gets people ramped up, connected, and excited about being at Antithesis.

• Run offboarding with the same level of care: exit interviews, system access removal, final pay coordination, and knowledge transfer logistics.

• Be the face of the employee lifecycle, making sure every person who joins or leaves has a great experience.

Benefits Administration

• Own benefits administration end to end, including health, dental, vision, life, disability, FSA/HSA, and any supplemental programs.

• Lead open enrollment from strategy through execution: communicate plan options clearly, field employee questions, coordinate with brokers and carriers, and ensure a smooth close.

• Serve as the primary point of contact for all benefits-related questions, claims issues, and escalations.

• Stay current on benefits trends, compliance requirements

• Manage relationships with benefits brokers, vendors, and carriers and hold them accountable to service standards.

People Operations & Systems

• Own Rippling as the day-to-day system of record: maintain accurate employee data, manage workflows, and use the platform to automate and improve People processes wherever possible.

• Support leave of absence administration (FMLA, state leave, parental leave) and coordinate with payroll as needed.

• Keep People policies and documentation current and easy to find.

• Maintain data integrity and reporting in Rippling to support headcount tracking, compliance, and decision-making.

What You'll Bring

• 3 to 6 years of People experience, with a meaningful chunk of that time spent owning benefits administration and open enrollment.

• Deep working knowledge of benefits programs, carrier relationships, broker partnerships, and compliance requirements (ACA, COBRA, ERISA, HIPAA).

• Hands-on Rippling expertise, you know the platform well and can build workflows, run reports, and troubleshoot without a lot of hand-holding.

• A track record of running smooth, high-quality onboarding and offboarding experiences that employees remember positively.

• High integrity, discretion, and sound judgment when handling sensitive employee information.

Nice to Have

• Familiarity with international People/HR or EOR setups.

• UK Benefits experience