FrontCoder: Scaling Visual Fidelity in Front-End Code Generation

Jun Feng, Jian Yang, Wei Zhang, Jing Wang, Keyi Chen, Xiaokun Yang, Weicheng Gu, Yihang Lou, Yan Bai, Xianglong Liu


Abstract
Large language models (LLMs) for code generation have achieved remarkable progress in synthesizing functional code from natural language instructions. However, a critical challenge persists in generating visually accurate and structurally sound front-end code that faithfully renders user-intended layouts and interfaces. Most existing works focus primarily on functional correctness, overlooking the visual fidelity and rendering quality essential for front-end development. To address this gap, we present a comprehensive data construction and training pipeline to enhance front-end code generation capabilities in code LLMs. We use a three-stage training approach: continual pre-training on synthetic data, quality-controlled supervised fine-tuning, and reinforcement learning with checklist-based rewards to improve model performance. Our comprehensive evaluation on front-end code generation benchmarks reveals that even strong base models struggle with visual faithfulness and layout complexity. Our fully-trained model demonstrated substantial improvements over baseline approaches across all domains, achieving competitive performance with frontier models while maintaining generation efficiency, underscoring the critical importance of stage-aligned data curation and vision-grounded optimization in developing reliable front-end code generation systems. Our code and data are open-sourced at https://github.com/leanfeng1/FrontCoder.
Anthology ID:
2026.findings-acl.220
Volume:
Findings of the Association for Computational Linguistics: ACL 2026
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
Findings
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Publisher:
Association for Computational Linguistics
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Pages:
4485–4505
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URL:
https://preview.aclanthology.org/ingest-acl/2026.findings-acl.220/
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Cite (ACL):
Jun Feng, Jian Yang, Wei Zhang, Jing Wang, Keyi Chen, Xiaokun Yang, Weicheng Gu, Yihang Lou, Yan Bai, and Xianglong Liu. 2026. FrontCoder: Scaling Visual Fidelity in Front-End Code Generation. In Findings of the Association for Computational Linguistics: ACL 2026, pages 4485–4505, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
FrontCoder: Scaling Visual Fidelity in Front-End Code Generation (Feng et al., Findings 2026)
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https://preview.aclanthology.org/ingest-acl/2026.findings-acl.220.pdf
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