FlowEval: Reference-based Evaluation of Generated User Interfaces

TL;DR

FlowEval is a reference-based framework that evaluates generated user interfaces by comparing interaction flows to real website traces, correlating well with expert human judgments.

Contribution

It introduces a scalable, reference-based evaluation method for UI generation that correlates with expert assessments, addressing limitations of existing methods.

Findings

Reference-based metrics strongly correlate with human judgments.

FlowEval provides a scalable and trustworthy evaluation for UI generation.

The framework uses dynamic time warping to compare navigation traces.

Abstract

While large language models (LLMs) and coding agents are often applied to user interface (UI) development, developers find it difficult to reliably assess their proficiency in visual and interaction design. Existing evaluations either rely on human experts, who can accurately assess usability by testing critical flows but are slow and costly, or on automated judges, which are scalable but less accurate and opaque. We present FlowEval, a reference-based framework that measures whether a generated UI supports realistic interaction flows by comparing navigation traces from real websites to traces from generated analogs using reference-based similarity metrics (e.g., dynamic time warping). In a small-scale study with expert UI evaluators, we show that reference-based metrics strongly correlate with human judgments, suggesting that they can provide scalable yet trustworthy evaluation for UI generation systems.