Senior Staff AI Engineer

SonicJobs; San Francisco (CA); On-site; USD 130,000 - 230,000; Full time

Job summary

SonicJobs is seeking a Senior Staff AI Engineer to lead the architecture and training of AI agents that enhance the job application process. This high-impact role involves fine-tuning models, designing experiments, and collaborating closely with the tech team to innovate. Ideal candidates should have a strong ML background, be hands-on with coding, and thrive in dynamic environments. Join a passionate team backed by top venture capital, shaping how job platforms operate.

Benefits

Real ownership

Opportunity to shape frontier technology

Diverse team environment

Qualifications

• Strong ML background with practical experience.
• Real experience fine-tuning LLMs and deep understanding of Reinforcement Learning.
• Hands-on coding experience and track record of high-impact research.

Responsibilities

• Fine-tune foundation models for computer-use.
• Design and run reinforcement learning systems.
• Lead strategy and mentor engineers.

Skills

Fine-tuning LLMs

Reinforcement Learning

Programming

Team Management

Education

PhD or equivalent in AI, ML, Computer Science

Job description

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At SonicJobs we’re building the next generation of autonomous web agents based on computer-use technologies. Our agents operate on job application flows, like candidates do. If you’ve ever dreamed of building AI that actually uses a website, this is your moment.

We’re a small, tight-knit team with big ambitions, leveraging bleeding-edge tools to build agents that understand and control web environments end-to-end.

We move fast, avoid unnecessary hierarchy, and aim high. We’re not automating job applications - we’re redefining how job applications work in order to allow candidates find the job opportunity they deserve.

We are backed by top VC firms and serve more than one hundred corporate clients including several Fortune 500 companies.

About the role

We’re looking for an AI master to own the architecture, training, and evolution of our AI agent stack. As Senior Staff AI Engineer, you’ll be responsible for fine-tuning LLMs that will support web-native agents capable of learning, adapting, and thriving in complex job application flows.

This is a demanding, high-impact role. You’ll be shipping code, training models, designing experiments, and setting our strategy at the same time. You’ll be reporting to the CTO. If you’re excited by the idea of coding, reviewing training runs, and designing new RL environments - you’ll thrive here. You’ll also be mentoring and growing colleagues to bring their agentic skills to a level of excellence.

What you'll do

• Fine-tune foundation models for computer-use using techniques like LoRA, PEFT, DPO, RLHF and similar depending on your judgment.
• Design and run reinforcement learning systems to improve agent reasoning and performance.
• Own the full agent stack: from policy models to interface planning & simulation frameworks.
• Prototype quickly, test aggressively, and constantly push the limits of what agents can do.
• Collaborate directly with the founding team on product direction and research priorities.
• Help grow a team of scrappy, mission-driven engineers and researchers.
• Create multi-agent flows with clear trajectories, role assignment, and long/short memory.

What you'll bring

• Strong ML background - PhD or equivalent experience in AI, ML, Computer Science or a strong industry experience.
• Real experience fine-tuning LLMs.
• Deep understanding of Reinforcement Learning (especially applied, not just theoretical).
• You’re hands-on: you like writing code, running experiments, and seeing real results.
• You’re driven by ownership, not job titles. You’re here to build, not manage for the sake of it.
• Experience in managing and growing teams.
• Track record of high-impact research published on meaningful or open-source contributions.
• Comfort working in fast-paced, exciting startup environments.

What we off

• Salary depends on experience.
• Onsite work with a deeply focused, no-BS te
• Real ownership and the chance to shape a frontier space.
• No corporate nonsense - just smart people building ambitious tech.

Sounds like you?

Let’s talk. This isn’t just a job - it’s a chance to lead the future of how job platform technology looks like.

Seniority level

• Seniority level

  Mid-Senior level

Employment type

• Employment type

  Full-time

Job function

• Job function

  Engineering and Information Technology

• Industries

  Technology, Information and Internet

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