Senior AI Engineer

AI Systems Engineer

We are building AI systems that generate production-quality motion from natural language. The system combines frontier language models, an AI generation harness, and a text-native Motion DSL designed for structured, editable animation.

This role spans two connected areas: improving the production generation system used today, and developing specialized models that can generate the Motion DSL directly with higher quality, lower latency, and better cost efficiency.

You will work at the intersection of LLM systems, post-training, code generation, compilers, evaluation, data engineering, and motion design. This is a hands-on engineering role with end-to-end ownership and measurable product impact.

Key Responsibilities

• Design and ship improvements across prompt interpretation, model orchestration, routing, retrieval, tool use, structured generation, validation, repair, and visual verification.
• Diagnose recurring failure modes and turn them into durable improvements in prompts, data, system logic, constraints, or evaluation.
• Build compiler-backed feedback loops and deterministic quality gates that prevent invalid or low-quality outputs from reaching users.
• Develop experiments and fixed evaluation batteries that show whether a change genuinely improves output quality.

Train specialized generative models

• Design supervised fine-tuning datasets, training recipes, and post-training experiments for direct Motion DSL generation.
• Explore distillation, preference optimization, synthetic-data generation, reinforcement-learning approaches, and constrained generation where they are the right tools.
• Select checkpoints using robust evaluations across correctness, visual quality, reliability, latency, and cost - not training loss alone.
• Determine whether a model failure is best addressed through data, training, inference, evaluation, or the underlying language/runtime.

Build the data and evaluation foundation

• Turn production generations into high-quality training and evaluation datasets using filtering, provenance, versioning, deduplication, and contamination controls.
• Design train, validation, and evaluation splits that minimize leakage and preserve meaningful generalization tests.
• Create failure taxonomies, hard negatives, regression suites, and representative prompt batteries.
• Combine deterministic checks, model-based judges, render evidence, and human review into a reliable evaluation system.

What we're looking for

• Strong ML and software engineering
• Hands-on LLM training experience
• Strong evaluation instincts
• Experience with structured or code generation
• Production engineering judgment
• Product and visual judgment

Nice to have

• Experience fine-tuning or evaluating code-generation models.
• Experience with multimodal or vision-language models.
• Experience building model-based, human-in-the-loop, or rubric-driven evaluation systems.
• Experience with compilers, interpreters, language tooling, or program analysis.
• Experience with Rust, PyTorch, or distributed training infrastructure.
• Experience with preference optimization, reinforcement learning, or synthetic-data pipelines.
• Experience with animation, graphics, rendering, or creative software.

LottieFiles Perks

• Fully Remote Working Environment
• Flexible Work Hours
• A welcome gift and LottieFiles swag pack
• Bonus to set up your workstation at home
• Unlimited Leave Days
• Medical Insurance
• Generous learning budget
• Gym membership
• Co-working space membership

Please note: To proceed with your application, you must confirm your acknowledgment of this Privacy Policy by ticking the checkbox on the next page.