Most AI products are wrappers. We're building the real thing, an agent that takes on genuine tasks for everyday users: running errands, managing workflows, holding context across long and complex conversations. Reliable by design, not by luck.

We're small, we move fast, and the ML layer is the product. We need someone to own it. The role You'll bridge research and production, taking ideas and turning them into systems that run at scale, stay reliable, and get better over time.

Full-stack ML ownership: from raw data to deployed model.

Day to day that looks like: Building end-to-end pipelines across data, training, evaluation, and inference Adapting and fine-tuning models with modern techniques: LoRA, QLoRA, SFT, DPO, distillation Architecting inference systems that hold up under real latency and cost constraints Creating data pipelines that produce high-quality synthetic and real-world training data Running evaluation that goes beyond benchmarks: robustness, safety, bias, production behaviour Owning deployment: GPU optimisation, quantisation, memory efficiency, scaling Working directly with application engineers so ML integrates cleanly into backend, mobile,



and desktop Your skills and experience Deep understanding of deep learning and transformer architectures Proven experience training, fine-tuning, or shipping large-scale models in production Strong with at least one major ML framework (PyTorch, JAX) and quick to pick up others Familiar with distributed training and inference tooling: DeepSpeed, FSDP, Megatron, ZeRO, Ray Engineering discipline: code that's readable, robust, and maintainable Experience optimising for GPU constraints: quantisation, mixed precision, memory Comfortable taking ownership of ambiguous problems from zero to one Ships, iterates, learns from production Nice to have LLM inference frameworks: vLLM, TensorRT-LLM, FasterTransformer RLHF: PPO, DPO, ORPO Open-source contributions to ML or systems libraries Scientific computing, compiler, or GPU kernel experience At a big company, ML work gets absorbed into a machine. Here, your systems are the product. You'll work closely with research and engineering leadership, have real influence over how the architecture evolves, and see the direct impact of your work on users.

If you want to build ML infrastructure that actually matters, this is it.

📌 (Senior) Machine Learning Engineer (Madrid)
🏢 Digital Waffle
📍 Madrid