Research Engineer (Reinforcement Learning)

About LiveKit

LiveKit is building the infrastructure layer for the voice-driven era of computing. Our platform gives developers everything they need to build, test, deploy, scale, and observe agents in production. Founded in 2021, LiveKit powers voice AI applications for OpenAI, xAI, Salesforce, Coursera, Spotify, and thousands of others, collectively facilitating billions of calls each year.

About This Role

We are looking for an exceptional engineer to build post-training at LiveKit. Our agents run over voice and increasingly over text channels like SMS and chat, and the interesting problems show up over long horizons: staying useful across many sessions, working with context that accumulates over time, and using tools reliably in the middle of a live conversation.

What You'll Do

Build the environments and verifiers our models train against

Own the synthetic data pipeline, from generation through the quality gates

Run training experiments end to end, and explain what moved the model

Build the evaluations a release has to clear

Choose and adapt open-weight base models for our tasks

Make trained behavior hold up for voice and text agents alike

Ship models into production and keep improving them on real usage

Who You Are

A strong Python engineer

Have carried a model from raw data through to production

Treat data as the product: coverage, diversity, leakage

Assume a model will exploit a weak reward, and design against it

Comfortable with GPUs and honest about their limits

Know when to train, and when not to

Comfortable working collaboratively in a remote environment

Nice to Have

Experience with post-training: fine-tuning, reward design, or reinforcement learning such as GRPO

RL and fine-tuning frameworks such as TRL, verl, or OpenRLHF, or a training loop you wrote yourself

Fast rollouts with vLLM or SGLang, multi-GPU training with FSDP

Training tool-using or multi-turn agents

Execution sandboxes, verifiers, eval harnesses, or tooling other engineers depend on

Open-weight families such as Qwen or Llama, LoRA and similar

Our Commitment to You

The opportunity to shape the brand of a fast-growing developer platform

Collaboration with a small, senior team that deeply values craft and creativity

Competitive salary and equity package

Health, dental, and vision benefits

Flexible vacation policy

LiveKit is an equal opportunity employer and does not discriminate on the basis of any characteristic protected by applicable law. If you require a reasonable accommodation during the application or interview process, please contact [email protected].