Research Engineer, Multimodal

Character.AI

Research Engineer on the Multimodal team at Character.AI building advanced AI video and image models. Lead fine-tuning, design architectures and collaborate to improve multimedia generation.

Posted 4/15/2026full-timeRedwood City • California • 🇺🇸 United StatesMid-LevelSenior💰 $225,000 - $400,000 per yearWebsite

Tech Stack

Tools & technologies

CloudDockerKubernetesPyTorch

About the role

Key responsibilities & impact

Lead fine-tuning and continued training of video generation models, including image-to-video and joint audio-visual generation.
Design and experiment with novel model architectures for multimodal generation, including multimodal conditioning (voice, structured text, reference images).
Leverage techniques such as LoRA, RLHF, and full-parameter fine-tuning to improve model quality across diverse visual scenarios.
Design and build large-scale data pipelines and automated annotation workflows to support continuous model improvement.
Explore model compression, inference acceleration, and serving optimizations to enable efficient real-time video processing at scale.

Requirements

What you’ll need

Strong passion for pushing the boundaries of visual AI, with a self-driven, hands-on approach to solving complex technical problems
Proficient in PyTorch with end-to-end experience across data processing, model training, and deployment
Solid understanding of video and image generation architectures, including diffusion models, DiT, ControlNet, and SOTA video generation models
Experience with multimodal model training, including working with audio, vision, and language modalities together
Experience with distributed training tools (FSDP, DeepSpeed, etc.)
Experience with large-scale data processing, dataset construction, and automated data cleaning
Experience with joint audio-visual or speech-conditioned generation models (Nice to Have)
Experience with AIGC, video effects, character animation, or asset generation products (Nice to Have)
Familiarity with ML deployment and orchestration (Kubernetes, Slurm, Docker, cloud platforms) (Nice to Have)
Publications in relevant venues (NeurIPS, ICLR, CVPR, ECCV, ICCV, or similar) (Nice to Have)

Benefits

Comp & perks

🩺 Top-notch health coverage for you & your family, with majority of the premium covered
💰 We invest in your future with a generous 401(K) contribution
🍼 New parents, we've got you covered with incredible paid leave -up to 20 weeks
🌴 4 weeks of PTO to explore, unwind & come back recharged
🍽️ Daily in-office catering plus a monthly Doordash stipend to help keep you fueled no matter where you are**
✨ Monthly wellness stipend to support you in your health journey

ATS Keywords

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Hard Skills & Tools

PyTorchvideo generation modelsimage-to-video generationmultimodal generationLoRARLHFmodel compressioninference accelerationdata processingautomated data cleaning

Soft Skills

self-drivenproblem-solvinghands-on approachpassion for visual AI