About Voltspan
Voltspan helps companies keep their data in their own hands and turn it into models of their own. We build from the power up: our own GPU clusters in US data centers, the sandboxes and inference agents run on, and the training behind them. We are growing across every layer of the stack.
About the role
Help agents get models of their own. You will train small open models that match much larger general models on our customers' agent tasks, using supervised fine-tuning and reinforcement learning on our GB300 and B300 clusters.
What you'll do
- Build SFT and RL pipelines for open models, from data loading to checkpoints
- Design rewards that check whether a task actually got done
- Run training at scale on our clusters and make it reliable
- Work with customers to scope a model, train it and ship it
What we're looking for
- Hands-on experience post-training open LLMs at scale
- Strong PyTorch and distributed training (FSDP, Megatron, DeepSpeed or similar)
- Experience with RL for LLMs (PPO, GRPO or similar)
Nice to have
- Training for tool use or multi-step agent tasks
- Published research or strong open-source work
Projects you might work on
- Train a small model that beats a frontier model on one customer's support agent
- Cut the time from a customer's traces to a first trained model from weeks to days
Logistics
San Jose, CA · Hybrid · Full-time
If a role excites you but you don't meet every qualification, apply anyway. We care more about what you have built than about a checklist.
Salary range, visa sponsorship and benefits will be added before this posting goes live.
How we work
- Small teams, big systems. Everyone here owns real infrastructure and real customers from week one.
- From volts to agents. Work moves across the whole stack, so you will see how your piece connects to power, GPUs, tokens and agents.
- We run what we build. The people who write the software also operate it, next to the people who rack the hardware.
Equal opportunity
Voltspan is an equal opportunity employer. We consider all qualified applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, veteran status or any other characteristic protected by law. We consider qualified applicants with arrest and conviction records in accordance with the California Fair Chance Act.
If you need an accommodation during the application process, let us know.