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Main Authors: Cho, Aeree, Greenhalgh, Alexander D., Bodea, Jonathan, Peng, Anthony, Horng, Duen, Chau
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.11549
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author Cho, Aeree
Greenhalgh, Alexander D.
Bodea, Jonathan
Peng, Anthony
Horng, Duen
Chau
author_facet Cho, Aeree
Greenhalgh, Alexander D.
Bodea, Jonathan
Peng, Anthony
Horng, Duen
Chau
contents Reinforcement learning has emerged as a dominant technique for fine-tuning the behavior of large language models, with policy optimization (PO) algorithms such as GRPO, DAPO, and Dr. GRPO emerging in rapid succession to advance state-of-the-art reasoning and alignment performance. However, the modular differences between these algorithms, including targeted improvements to clipping, advantage estimation, and reward aggregation, are introduced across separate papers with inconsistent notation, making them difficult to compare and intimidating to the non-expert community. We present UNIPO, the first interactive visualization tool that exposes the token-level training dynamics of RL fine-tuning algorithms through a unified design. UNIPO connects three complementary views, a high-level training overview, a step-level prompt and response inspector, and a side-by-side algorithm comparison, allowing learners to observe how individual design decisions propagate through training. Through two usage scenarios, we demonstrate how UNIPO supports both classroom instruction for non-experts and algorithm selection for AI practitioners. Our tool is open-source and publicly available at https://poloclub.github.io/unipo.
format Preprint
id arxiv_https___arxiv_org_abs_2605_11549
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle UNIPO: Unified Interactive Visual Explanation for RL Fine-Tuning Policy Optimization
Cho, Aeree
Greenhalgh, Alexander D.
Bodea, Jonathan
Peng, Anthony
Horng, Duen
Chau
Human-Computer Interaction
Reinforcement learning has emerged as a dominant technique for fine-tuning the behavior of large language models, with policy optimization (PO) algorithms such as GRPO, DAPO, and Dr. GRPO emerging in rapid succession to advance state-of-the-art reasoning and alignment performance. However, the modular differences between these algorithms, including targeted improvements to clipping, advantage estimation, and reward aggregation, are introduced across separate papers with inconsistent notation, making them difficult to compare and intimidating to the non-expert community. We present UNIPO, the first interactive visualization tool that exposes the token-level training dynamics of RL fine-tuning algorithms through a unified design. UNIPO connects three complementary views, a high-level training overview, a step-level prompt and response inspector, and a side-by-side algorithm comparison, allowing learners to observe how individual design decisions propagate through training. Through two usage scenarios, we demonstrate how UNIPO supports both classroom instruction for non-experts and algorithm selection for AI practitioners. Our tool is open-source and publicly available at https://poloclub.github.io/unipo.
title UNIPO: Unified Interactive Visual Explanation for RL Fine-Tuning Policy Optimization
topic Human-Computer Interaction
url https://arxiv.org/abs/2605.11549