LongWebBench: Evaluating Structural and Functional Webpage Generation in Long-Horizon Settings

Yi Zhao, Zhen Yang, Mengpan Chen, Mingde Xu, ShangHui Gong, Xijun Liu, Jibing Gong, Jie Tang


Abstract
Recent vision-language models (VLMs) have shown promising progress in generating webpages from visual inputs, yet existing evaluations mainly focus on short, single-screen, and largely static webpages. We introduce LongWebBench, a benchmark for evaluating long-horizon webpage generation from both structural and functional perspectives. LongWebBench contains 490 real-world long webpages for structural fidelity evaluation and 507 goal-oriented interaction tasks over 129 webpages for functional evaluation. It employs two complementary protocols: a multi-dimensional VLM-based metric for assessing long-range structural coherence, and a DOM-augmented agent-based pipeline for end-to-end functional verification. We further examine the automatic evaluation protocols through human agreement analysis. Experiments with state-of-the-art open-source and proprietary VLMs under single-image and multi-image settings reveal that structural fidelity degrades as webpage length increases, while visually plausible generations often fail to support executable multi-step interactions. These results highlight the need to evaluate long webpage generation beyond visual similarity, with executable interaction as a core criterion. Our code and data are available at https://github.com/zhaoyi-hb/LongWebBench.
Anthology ID:
2026.emnlp-main.2023
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
46064–46115
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URL:
https://aclanthology.org/2026.emnlp-main.2023/
DOI:
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Cite (ACL):
Yi Zhao, Zhen Yang, Mengpan Chen, Mingde Xu, ShangHui Gong, Xijun Liu, Jibing Gong, and Jie Tang. 2026. LongWebBench: Evaluating Structural and Functional Webpage Generation in Long-Horizon Settings. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 46064–46115, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LongWebBench: Evaluating Structural and Functional Webpage Generation in Long-Horizon Settings (Zhao et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2023.pdf