Data Science/ML Engineer en HIRELINE

Team and Responsibilities

We are seeking Senior AI/ML Engineers to join a new, forward-thinking AI team, established in Mexico City. This team will focus on building enterprise production-ready AI solutions at scale. The ideal candidates are technical operators with a strong backend platform focus who can drive innovation in the expense platform. Strong focus on model development, fine-tuning, and AI workflow creation.

Location: Mexico City: 1 o 2 times a month in-office presence

Advanced english required

What You'll Do:

• Design, develop, and deploy AI-driven services and workflows ("agents") for the American Express expense platform.

• Focus on RAG (Retrieval-Augmented Generation) implementations, fine-tuning models, and building robust LLM workflows in production.

• Develop solutions for key features such as recommendations, predictions, chatbots for dashboard analytics, and smart receipt generation.

• Implement high standards for observability, testability, and metrics for all AI models and systems.

• Work in a collaborative, fast-paced environment to deliver enterprise-grade solutions.

Required Technical Skills & Experience:

• Senior-level experience in developing production-ready, scalable enterprise solutions.

• Strong proficiency in Golang (at least 5 years)  in backend engineer and React. Prior non-AI-related Golang experience is acceptable.

Strong applied experience with LLMs, RAG, fine-tuning, embeddings, and inference workloads.

• Hands-on experience building production AI systems (not only experimentation or prototypes).

• Strong knowledge of LLM mechanics, neural networks, prompting, embeddings, and evaluation.

• AI/ML Expertise: Deep understanding of the mechanics of LLMs, neural networks, training, fine-tuning, and AB testing/versioning models.

• Experience with cloud infrastructure and practical ML experience (especially for the Backend Platform Engineer role).

• Soft Skills: Strong professional working proficiency in English is required.

Excellent English communication; prior experience working with US-based teams is a strong plus.

• Candidates must have experience in implementing observability, testability, and metrics, as there is scrutiny on decisions made by AI models,

• Strong ownership and autonomous execution.

• Ability to work in fast-paced, ambiguous environments.

• Team-first mindset with a focus on collaboration and communication.

• “Technical operator” mentality—able to design, build, and run production systems end-to-end.