---
title: Unlimited-OCR
description: "Deploy Baidu Unlimited-OCR with SGLang for long document OCR using prefill-aware sliding-window attention."
---

## Deployment

<a id="install" />

<Accordion title="Install SGLang">

Unlimited-OCR support is in [SGLang PR #29186](https://github.com/sgl-project/sglang/pull/29186). Until that PR is included in a tagged SGLang release, install from a build that contains the PR.

<Tabs>

<Tab title="Python (pip / uv)">

```bash Command
pip install -U uv
uv venv --python 3.12 && source .venv/bin/activate

git clone https://github.com/sgl-project/sglang.git
cd sglang
git fetch origin pull/29186/head && git checkout FETCH_HEAD
uv pip install --prerelease=allow -e python
```

Then run the **Python** output of the command panel below in that environment.

</Tab>

<Tab title="Docker">

```bash Command
docker pull lmsysorg/sglang:dev
```

For how to launch the image, see [Install → Method 3: Using Docker](../../../docs/get-started/install#method-3-using-docker). Substitute the inner `sglang serve ...` with what the command generator below produces.

</Tab>

</Tabs>

</Accordion>

Pick your hardware to generate the launch command. The recipe uses FlashAttention-3 with `--page-size 1`, which is required by the current prefill-aware sliding-window attention path. It also disables radix cache by default, which is the better fit for batch OCR workloads where each request usually contains a different image.

import { Deployment } from "/src/snippets/_deployment.jsx";
import { config } from "/src/snippets/configs/baidu/unlimited-ocr.jsx";

<Deployment config={config} />

## Playground

Use the Playground to adjust tensor parallelism on top of the selected deployment cell.

import { Playground } from "/src/snippets/_playground.jsx";

<Playground config={config} />

## 1. Model Introduction

[Unlimited-OCR](https://huggingface.co/baidu/Unlimited-OCR) is Baidu's multimodal OCR model for document parsing. It uses a sliding-window language backbone, but SGLang serves it with a prefill-aware sliding-window path so image and prompt tokens remain visible during long decode.

The SGLang integration loads the standalone Unlimited-OCR architecture with SAM and CLIP vision encoders plus a DeepSeek-style language backbone. It supports OpenAI-compatible image requests and model-specific image processing options through `images_config`.

**Resources:** [Hugging Face](https://huggingface.co/baidu/Unlimited-OCR) · [SGLang PR #29186](https://github.com/sgl-project/sglang/pull/29186)

## 2. Configuration Tips

- **Attention backend**: use `--attention-backend fa3 --page-size 1`. The prefill-aware SWA page table is built with token-level locations, so page size 1 is required.
- **Radix cache**: keep `--disable-radix-cache` for batch OCR over different documents. If your workload repeatedly asks about the same image and prompt, remove this flag to allow prefix reuse through `PureSWARadixCache`.
- **Long OCR generations**: keep the default prefill-aware SWA path enabled. It retains prompt and image KV while still applying a sliding window to generated text.
- **Custom logit processor**: keep `--enable-custom-logit-processor` in the launch command.
- **Image modes**: pass `images_config.image_mode` per request. Supported modes are `tiny`, `small`, `base`, `large`, and `gundam`. Multiple images are supported only for `tiny`, `small`, and `base`.
- **Default image mode**: when `images_config.image_mode` is omitted, SGLang uses `gundam`.

## 3. Advanced Usage

### 3.1 OCR request

<Accordion title="OCR Example (Python)">

```python Example
from openai import OpenAI

client = OpenAI(base_url="http://localhost:30000/v1", api_key="EMPTY")

response = client.chat.completions.create(
    model="baidu/Unlimited-OCR",
    messages=[
        {
            "role": "user",
            "content": [
                {"type": "text", "text": "document parsing."},
                {
                    "type": "image_url",
                    "image_url": {
                        "url": "https://example.com/your_document.png"
                    },
                },
            ],
        }
    ],
    max_tokens=2048,
    temperature=0,
    extra_body={"images_config": {"image_mode": "gundam"}},
)

print(response.choices[0].message.content)
```

</Accordion>

### 3.2 Choosing an image mode

Use lower modes to reduce prefill cost for simple images, and use `gundam` for high-detail document parsing.

<table style={{width: "100%", borderCollapse: "collapse", tableLayout: "fixed"}}>
  <thead>
    <tr style={{borderBottom: "2px solid #d55816"}}>
      <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700}}>Mode</th>
      <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700}}>Use</th>
      <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700}}>Multiple images</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td style={{padding: "9px 12px"}}><code>tiny</code></td>
      <td style={{padding: "9px 12px"}}>Lowest prefill cost.</td>
      <td style={{padding: "9px 12px"}}>Yes</td>
    </tr>
    <tr>
      <td style={{padding: "9px 12px"}}><code>small</code></td>
      <td style={{padding: "9px 12px"}}>Lightweight OCR requests.</td>
      <td style={{padding: "9px 12px"}}>Yes</td>
    </tr>
    <tr>
      <td style={{padding: "9px 12px"}}><code>base</code></td>
      <td style={{padding: "9px 12px"}}>Balanced quality and cost.</td>
      <td style={{padding: "9px 12px"}}>Yes</td>
    </tr>
    <tr>
      <td style={{padding: "9px 12px"}}><code>large</code></td>
      <td style={{padding: "9px 12px"}}>Higher resolution single-image OCR.</td>
      <td style={{padding: "9px 12px"}}>No</td>
    </tr>
    <tr>
      <td style={{padding: "9px 12px"}}><code>gundam</code></td>
      <td style={{padding: "9px 12px"}}>Default high-detail document parsing mode.</td>
      <td style={{padding: "9px 12px"}}>No</td>
    </tr>
  </tbody>
</table>