Founding ML Engineer (AI)

Location: On-site in Belgrade, Serbia or Lisbon, Portugal.

Company

hirify.global is an integrated commerce, liveops automation, community engagement, and payments platform for video games that helps studios sell directly and build relationships with players.

What you will do

• Lead Newton's transition from proprietary model APIs to self-hosted and open-weight models while preserving production quality, reducing cost, improving speed, and keeping partner data within hirify.global's infrastructure.
• Build production data pipelines covering versioned instructions, tool calls, outputs, costs, outcomes, anonymization, partner-level deletion, and expert corrections.
• Develop benchmarks, regression tests, behavior tests, and code-based and LLM-judge evaluators for factual accuracy, tool use, answer quality, cost, and latency.
• Compare frontier and open-weight models, route tasks to suitable models, and determine when prompting, distillation, or post-training is most effective.
• Train, adapt, deploy, and validate models using distillation, SFT, LoRA/QLoRA, DPO, shadow runs, and production rollouts; use RL when simpler approaches are insufficient.
• Work with product stakeholders to translate partner expectations into measurable quality requirements and independently set the technical approach and priorities.

Requirements

• Senior or Principal-level experience independently owning a technical area, setting priorities, and working across unfamiliar codebases and design documents.
• Hands-on experience post-training LLMs and shipping them to production using SFT, LoRA/QLoRA, DPO, and distillation.
• Experience building evaluation systems from production data, including offline benchmarks, regression and behavior tests, and code-based and LLM-judge evaluators.
• Understanding of agentic systems, including tool calling, multi-step trajectories, structured outputs, and the impact of changing the underlying model.
• Practical experience serving models with vLLM or similar tools, quantization, and GPU deployment, including latency, cold-start, and cost tradeoffs.
• Strong production Python and SQL skills, with enough TypeScript proficiency to modify product code and instrumentation independently.
• Ability to understand product behavior and user expectations, translate them into measurable quality requirements, and decide when training is justified.
• Regular use of AI coding agents with a clear approach to verifying their output.

Nice to have

• Experience migrating a production product from proprietary model APIs to self-hosted or open-weight models.
• Experience with RL for LLMs, particularly GRPO with automatic verifiers.
• Familiarity with Langfuse, Braintrust, or similar tracing and evaluation tools.
• Experience with GCP, including Vertex AI, Cloud Run GPU, and BigQuery.
• Interest in game monetization and analytics.

Culture & Benefits

• Work with experienced professionals from around the globe who have built products used by millions of players.
• Join a fast-growing, high-impact environment where ideas can reach customers in days.
• Operate with autonomy and ownership, making decisions and driving results.
• Use AI, automation, and modern tools in everyday work.
• Receive equity participation in the company's growth and long-term success.