Senior Principal ML Engineer: RL/LLM for Marketplaces

Grab; Singapore; On-site; SGD 180,000 - 300,000; Full time

Benefits offered by this job

Term Life Insurance

Medical Insurance

GrabFlex

Job summary

Grab's Fulfilment Tech team in Singapore is seeking a Senior Principal Machine Learning Engineer to lead autonomous marketplace systems. You will design RL-based pricing, dispatch, and supply strategies at scale, integrating RL and LLM components with production infrastructure to serve millions of users and driver-partners.

As a technical lead, you will mentor a small team, translate complex business problems into modelling tasks, and work closely with data and backend engineers to deploy

Qualifications

• PhD in Computer Science, Operations Research, Applied Mathematics, or related field with at least 10 years of experience.
• Proficient in RL fundamentals and reward design for marketplace applications.
• Experience building production ML/RL systems with online learning or simulation-based optimization.
• Knowledge of world models and sequential modelling (RNNs, transformers).
• Hands-on experience fine-tuning large language models in production (RLHF/ROE/DP0).
• Experience with distributed training frameworks (DeepSpeed, FSDP, Megatron-LM).
• Proficiency in Python and ML frameworks (PyTorch/TensorFlow).
• Experience with Spark or Ray for large-scale data.
• Ability to translate business problems into modelling tasks.

Responsibilities

• Design end-to-end RL systems combining model-based RL, offline RL, simulation, and online learning.
• Build latent world models capturing supply-demand interactions and behaviours.
• Develop multi-lever optimization for pricing, dispatch, and repositioning.
• Create policy evaluation frameworks and monitoring for safe production deployment.
• Fine-tune language models for prediction, reasoning, and simulation in marketplace apps.
• Develop training strategies for language models including supervised fine-tuning and alignment.
• Collaborate with data and backend engineers to deploy RL/LLM in production serving millions.

Skills

RL fundamentals

Production ML/RL

World models

LLM fine-tuning

LoRA/PEFT

Distributed training

Python & PyTorch

Spark or Ray

Policy evaluation

Reinforcement Learning

Education

PhD in CS/OR/Applied Mathematics

Tools

DeepSpeed

FSDP

Megatron-LM

Job description

Grab's Fulfilment Tech team in Singapore is seeking a Senior Principal Machine Learning Engineer to lead autonomous marketplace systems. You will design RL-based pricing, dispatch, and supply strategies at scale, integrating RL and LLM components with production infrastructure to serve millions of users and driver-partners.

As a technical lead, you will mentor a small team, translate complex business problems into modelling tasks, and work closely with data and backend engineers to deploy