WebWorld ๐#
License GitHub Dataset MS Dataset 8B MS 8B 14B MS 14B 32B MS 32B
๐ Introduction#
WebWorld is a large-scale open-web world model series for training and evaluating web agents. It is trained on 1M+ real-world web interaction trajectories via a scalable hierarchical data pipeline, supporting:
Long-horizon simulation (30+ steps)Multi-format state representations : A11y Tree, HTML, XML, Markdown, and natural languageCoT-activated reasoning for transition predictionCross-domain generalization to code, GUI, and game environments
Agents trained on WebWorld-synthesized trajectories achieve +9.9% on MiniWob++ and +10.9% on WebArena . When used for inference-time lookahead search, WebWorld outperforms GPT-5 as a world model.
๐ฏ Model Series#
WebWorldData : Huggingface: Qwen/WebWorldData , ModelScope: Qwen/WebWorldData
๐ก Recommendation : Use 8B for fast simulation and data synthesis; use 14B/32B for higher-fidelity simulation and better long-horizon robustness. For best results in a specific environment, we recommend task-specific fine-tuning on in-domain trajectories.
๐ ๏ธ Requirements#
transformers (recommended: latest version)torchOptional: accelerate, vllm for efficient serving
๐ Quick Start#
Key Notes:
WebWorld predicts the next page state given the current state and an action. It strictly preserves the input/output format (A11y / HTML / XML / Markdown / NL). Supports multi-turn trajectory simulation up to 30+ steps.
Single-Step Prediction#
๐ป Click to expand code
import torch
from transformers import AutoTokenizer, AutoModelForCausalLM
model_name = "Qwen/WebWorld-8B" # or WebWorld-14B, WebWorld-32B
tokenizer = AutoTokenizer.from_pretrained(model_name, trust_remote_code=True)
model = AutoModelForCausalLM.from_pretrained(
model_name,
device_map="auto",
torch_dtype=torch.bfloat16,
trust_remote_code=True,
).eval()
system_prompt = (
"You are a web world model. I will provide you with an initial page state "
"and a sequence of actions. For each action, predict the resulting page state.\n"
"Strictly maintain the original format. Output only the full page state "
"without explanations, code, or truncation."
)
current_state = """RootWebArea 'Global Start - Your Daily Portal', focused
\t[1] banner 'Top Header', visible
\t\t[2] link 'Set as Homepage', clickable, visible
\t\t[3] link 'Feedback', clickable, visible
\t\t[5] region 'Weather Widget', visible
\t\t\tStaticText 'New York, USA'
\t\t\t[6] image 'Sunny', visible
\t\t\tStaticText '24ยฐC'
\t\t[8] link 'Sign In', clickable, visible
\t[10] region 'Search Area', visible
\t\t[11] image 'Global Start Logo', visible
\t\tStaticText 'Search the entire web'
\t\t[12] tablist 'Search Engine Selector', orientation='horizontal'
\t\t\t[13] tab 'Google', selected=True, clickable
\t\t\t[14] tab 'Bing', selected=False, clickable
\t\t\t[15] tab 'DuckDuckGo', selected=False, clickable
\t\t[18] combobox 'Web Search', clickable, visible, autocomplete='both', expanded=False
\t\t\t[19] textbox 'Type keywords or URL...', clickable, visible, editable, value=''
\t\t[20] button 'Search', clickable, visible
\t[30] navigation 'Category Bar', visible
\t\t[31] link 'Home', clickable, selected=True
\t\t[32] link 'News', clickable
\t\t[33] link 'Video', clickable
\t\t[34] link 'Shopping', clickable
\t\t[35] link 'Social', clickable
\t[50] main 'Site Directory', visible
\t\t[51] region 'Top Recommended', visible
\t\t\t[52] heading 'Most Popular', visible
\t\t\t[53] list 'Top Sites Grid', visible
\t\t\t\t[54] link 'Facebook', clickable
\t\t\t\t[56] link 'YouTube', clickable
\t\t\t\t[58] link 'Amazon', clickable
\t\t\t\t[60] link 'Twitter / X', clickable
\t\t\t\t[62] link 'Instagram', clickable
\t\t\t\t[64] link 'Wikipedia', clickable
\t\t\t\t[66] link 'Netflix', clickable
\t\t\t\t[68] link 'LinkedIn', clickable
\t\t[80] region 'News & Media', visible
\t\t\t[81] heading 'Latest News', visible
\t\t\t[82] link 'CNN', clickable
\t\t\t[83] link 'BBC', clickable
\t\t\t[84] link 'The Verge', clickable
\t\t[90] region 'Shopping', visible
\t\t\t[91] heading 'E-Commerce', visible
\t\t\t[92] link 'eBay', clickable
\t\t\t[93] link 'Walmart', clickable
\t\t\t[94] link 'Best Buy', clickable
\t[200] complementary 'Ads', visible
\t\t[201] image 'Ad: Travel to Japan'
\t\t[202] link 'Book Now', clickable
\t[300] contentinfo 'Footer', visible
\t\tStaticText 'ยฉ 2026 Global Start Inc.'"""
user_message = (
f"Initial Page State:\n{current_state}\n\n"
f"First Action: 'click([32])'\n\n"
f"Next Page State:"
)
messages = [
{"role": "system", "content": system_prompt},
{"role": "user", "content": user_message},
]
text = tokenizer.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = tokenizer(text, return_tensors="pt").to(model.device)
with torch.no_grad():
outputs = model.generate(
**inputs,
max_new_tokens=4096,
do_sample=False,
)
response = tokenizer.decode(outputs[0][inputs["input_ids"].shape[-1]:], skip_special_tokens=True)
print(response) Copy
Multi-Turn Simulation#
The first turn provides the initial state and first action. Each subsequent turn uses a fixed continuation prompt:
๐ป Click to expand code
CONTINUE_PROMPT = (
"Continue the trajectory. Given the previous state, "
"predict the next page state after this action.\n\n"
"Action: '{action}'\n\nNext Page State:"
)
# Turn 1
messages = [
{"role": "system", "content": system_prompt},
{"role": "user", "content": f"Initial Page State:\n{state_0}\n\nFirst Action: '{action_0}'\n\nNext Page State:"},
]
state_1 = generate(messages) # your generate function
# Turn 2
messages.append({"role": "assistant", "content": state_1})
messages.append({"role": "user", "content": CONTINUE_PROMPT.format(action=action_1)})
state_2 = generate(messages)
# Turn 3, 4, ... up to 30+ turns: repeat the same pattern
messages.append({"role": "assistant", "content": state_2})
messages.append({"role": "user", "content": CONTINUE_PROMPT.format(action=action_2)})
state_3 = generate(messages) Copy
๐ฎ Action Space#
WebWorld supports a unified action space as Python-style function calls:
Category Action Description Element click(bid, button, modifiers)Click a DOM element by its ID fill(bid, text, press_enter)Type text into an input field select_option(bid, options)Select from a dropdown / combobox hover(bid)Hover over an element Mouse mouse_move(x, y)Move cursor to coordinates mouse_click(x, y, button)Click at coordinates mouse_down(x, y) / mouse_up(x, y)Press / release (drag-and-drop) Keyboard keyboard_press(key)Press a key (e.g., Enter, Tab) keyboard_type(text)Type a string sequentially Browser scroll(dx, dy)Scroll the viewport goto(url)Navigate to a URL go_back() / go_forward()Browser history navigation tab_new() / tab_close() / tab_focus(index)Manage browser tabs Meta send_msg_to_user(text)Send a message to the user noop(wait_ms)Wait for a duration infeasible(reason)Declare the task impossible
Intrinsic Evaluation (WebWorld-Bench)#
WebWorld-Bench evaluates models using Factuality Score (functional correctness) and Web Turing Score (perceptual realism) across nine dimensions:
Model Avg Factuality Avg Turing GPT-4o 59.5 35.4 Claude-Opus-4.1 71.3 47.4 Gemini-3-Pro 70.3 43.2 Qwen3-8B (base) 26.9 17.4 WebWorld-8B 70.1 42.2 WebWorld-14B 70.7 44.7 WebWorld-32B 71.0 45.6
Extrinsic Evaluation (Agent Training)#
Model MiniWob++ SR WebArena SR GPT-4o 64.3% 26.6% Qwen3-8B (base) 49.4% 9.8% Qwen3-8B + WebWorld 59.3% (+9.9%)20.7% (+10.9%)Qwen3-14B (base) 54.9% 15.1% Qwen3-14B + WebWorld 63.2% (+8.3%)24.3% (+9.2%)
Cross-Domain Generalization#
Environment Qwen3-8B WebWorld-8B Gain API Services 0.088 0.299 +0.211 Code 0.147 0.396 +0.249 Game 0.253 0.473 +0.220 GUI Desktop 0.322 0.705 +0.383
โ ๏ธ Limitations#
Sycophancy / optimism bias : the model may generate outcomes that are overly favorable to the agent's intended action.Content generation fidelity : long-form, high-precision content (e.g., scientific articles) is not the primary target.Text-only : WebWorld does not simulate visual / pixel-level rendering.
๐ Citation#
@misc{xiao2026webworldlargescaleworldmodel,
title={WebWorld: A Large-Scale World Model for Web Agent Training},
author={Zikai Xiao and Jianhong Tu and Chuhang Zou and Yuxin Zuo and Zhi Li and Peng Wang and Bowen Yu and Fei Huang and Junyang Lin and Zuozhu Liu},
year={2026},
eprint={2602.14721},
archivePrefix={arXiv},
primaryClass={cs.AI},
url={https://arxiv.org/abs/2602.14721},
} Copy