---
title: "PDF optimization API"
canonical_url: "https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-optimization-api/"
md_url: "https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-optimization-api.md"
last_updated: "2026-07-06T00:00:00.000Z"
description: "Optimize and compress PDF files using Nutrient DWS Processor API. Reduce file size with image optimization, MRC compression, grayscale conversion, and image removal options."
---

# PDF optimization API

Use the PDF optimization API to reduce PDF file size and prepare documents for storage, sharing, or delivery. Nutrient DWS Processor API supports image optimization, mixed raster content (MRC) compression, grayscale conversion, image removal, and linearization options.

The [`/build` endpoint](https://www.nutrient.io/api/reference/public/#tag/Document-Editing/operation/build-document) handles PDF optimization. Add the source PDF as a `parts` item, set `output.type` to `pdf`, and configure `output.optimize`.

For signup, pricing, and task-level examples, refer to the [PDF optimization API task page](https://www.nutrient.io/api/pdf-optimization-api/).

## Optimize a PDF

The following example optimizes `document.pdf` with image optimization and MRC compression and writes the output to `result.pdf`:

### Shell

### Shell (Windows)

### Java

### C#

### JavaScript

### Python

### PHP

### HTTP

## Adjust image optimization quality

Use `imageOptimizationQuality` to control the tradeoff between file size and image quality. Supported values are `1`, `2`, `3`, and `4`.

- `1` — Lowest file size and strongest compression.

- `2` — Balanced compression. Processor API examples use this value by default.

- `3` — Higher image quality.

- `4` — Highest image quality and lowest compression.

Use this instructions object to set image optimization quality:

```json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "imageOptimizationQuality": 1
    }
  }
}

```

Review optimized output visually when image fidelity matters.

## Use MRC compression for scanned PDFs

MRC compression works well for scanned documents and mixed raster content. It can reduce file size while preserving readable text and important visual details.

Use this instructions object to enable MRC compression:

```json

{
  "parts": [
    {
      "file": "scanned_document"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "mrcCompression": true,
      "imageOptimizationQuality": 2
    }
  }
}

```

## Convert content to grayscale

Use grayscale options when color isn’t required and you want to reduce output size or normalize document appearance.

Use this instructions object to convert content to grayscale:

```json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "grayscaleText": true,
      "grayscaleGraphics": true,
      "grayscaleImages": true,
      "grayscaleFormFields": true,
      "grayscaleAnnotations": true
    }
  }
}

```

You can enable these options independently for text, graphics, images, form fields, and annotations.

## Remove images

Set `disableImages` to `true` to remove images from the output PDF. Use this option only when images aren’t required in the final document.

Use this instructions object to remove images:

```json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "disableImages": true
    }
  }
}

```

Removing images can reduce file size, but it changes the document’s visual appearance.

## Optimize a PDF from a URL

For remotely hosted source files, send a JSON request and pass the source URL in `parts[].file.url`. Use this instructions object:

```json

{
  "parts": [
    {
      "file": {
        "url": "https://example.com/document.pdf"
      }
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "mrcCompression": true,
      "imageOptimizationQuality": 2
    }
  }
}

```

### Shell

Run this request to optimize a PDF from a URL:

```bash

curl -X POST https://api.nutrient.io/build \
  -H "Authorization: Bearer $NUTRIENT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "parts": [
      {
        "file": {
          "url": "https://example.com/document.pdf"
        }
      }
    ],
    "output": {
      "type": "pdf",
      "optimize": {
        "mrcCompression": true,
        "imageOptimizationQuality": 2
      }
    }
  }' \
  -o result.pdf

```

## Optimize selected PDF pages

Use `parts[].pages` to optimize only a page range from the source PDF. Page indexes are zero-based, and negative values count from the end of the document.

The following example optimizes only the first three pages:

```json

{
  "parts": [
    {
      "file": "document",
      "pages": {
        "start": 0,
        "end": 2
      }
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "imageOptimizationQuality": 2
    }
  }
}

```

The `end` value is inclusive, so `{ "start": 0, "end": 2 }` includes pages zero, one, and two.

## Optimize password-protected PDFs

If the source PDF is password-protected, include the password on the part. Use this instructions object:

```json

{
  "parts": [
    {
      "file": "protected_document",
      "password": "document-password"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "imageOptimizationQuality": 2
    }
  }
}

```

Nutrient DWS Processor API uses the password only to open the source document for processing. To set a password on the optimized output PDF, configure `output.user_password`, `output.owner_password`, and `output.user_permissions`.

## Optimize and linearize for web delivery

You can combine optimization with linearization. Linearization restructures the PDF so viewers that support byte-range requests can load it incrementally over the network.

Use this instructions object to optimize and linearize a PDF:

```json

{
  "parts": [
    {
      "file": "document"
    }
  ],
  "output": {
    "type": "pdf",
    "optimize": {
      "mrcCompression": true,
      "imageOptimizationQuality": 2,
      "linearize": true
    }
  }
}

```

For more details, refer to the [PDF linearization API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-linearization-api.md) guide.

## Use optimization before signing

Optimization changes the PDF file. If your workflow includes cryptographic signing, optimize the document before signing it. Treat signed PDFs as final artifacts.

A typical workflow includes these steps:

1. Merge, split, rotate, fill forms, redact, or watermark the document.

2. Optimize or linearize the final output.

3. Apply a digital signature last, if required.

## Reference

A PDF optimization request uses the Build API `output.optimize` object:

```typescript

type OptimizePdf = {
  grayscaleText?: boolean;
  grayscaleGraphics?: boolean;
  grayscaleImages?: boolean;
  grayscaleFormFields?: boolean;
  grayscaleAnnotations?: boolean;
  disableImages?: boolean;
  mrcCompression?: boolean;

  // Supported values are 1 through 4.
  imageOptimizationQuality?: 1 | 2 | 3 | 4;

  // Linearize the output PDF for fast web viewing.
  linearize?: boolean;
};

type PDFOutput = {
  type: "pdf";
  optimize?: OptimizePdf;
};

type FilePart = {
  // Multipart field name, or a remote URL object.
  file: string | { url: string };

  // Optional password for encrypted input PDFs.
  password?: string;

  // Optional page range to optimize.
  pages?: {
    start?: number;
    end?: number;
  };
};

type BuildInstructions = {
  parts: FilePart[];
  output: PDFOutput;
};

```

## Related API reference operations

- Refer to the [build document endpoint](https://www.nutrient.io/api/reference/public/#tag/Document-Editing/operation/build-document) API reference to optimize PDFs and combine optimization with page selection, document assembly, security, or linearization.

## Related guides

- Refer to the [PDF linearization API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-linearization-api.md) guide.

- Refer to the [PDF security API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-security-api.md) guide.

- Refer to the [PDF digital signature API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-digital-signature-api.md) guide.

- Refer to the [PDF merge API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-merge-api.md) guide.

- Refer to the [PDF split API](https://www.nutrient.io/guides/dws-processor/tools-and-api/pdf-split-api.md) guide.

- Refer to the [tools and APIs](https://www.nutrient.io/guides/dws-processor/tools-and-api.md) guide.
---

## Related pages

- [Image-to-PDF API](/guides/dws-processor/tools-and-api/image-to-pdf-api.md)
- [Analyze Build API](/guides/dws-processor/tools-and-api/analyze-build-api.md)
- [Tools and APIs](/guides/dws-processor/tools-and-api.md)
- [Document-to-image API](/guides/dws-processor/tools-and-api/document-to-image-api.md)
- [Import Instant JSON API](/guides/dws-processor/tools-and-api/import-instant-json-api.md)
- [DOCX templating API](/guides/dws-processor/tools-and-api/docx-templating-api.md)
- [Import XFDF annotations API](/guides/dws-processor/tools-and-api/import-xfdf-annotations-api.md)
- [Office-to-PDF API](/guides/dws-processor/tools-and-api/office-to-pdf-api.md)
- [Markdown-to-PDF API](/guides/dws-processor/tools-and-api/markdown-to-pdf-api.md)
- [PDF digital signature API](/guides/dws-processor/tools-and-api/pdf-digital-signature-api.md)
- [PDF merge API](/guides/dws-processor/tools-and-api/pdf-merge-api.md)
- [PDF form filling API](/guides/dws-processor/tools-and-api/pdf-form-filling-api.md)
- [PDF flatten API](/guides/dws-processor/tools-and-api/pdf-flatten-api.md)
- [PDF OCR API](/guides/dws-processor/tools-and-api/pdf-ocr-api.md)
- [PDF generator API](/guides/dws-processor/tools-and-api/pdf-generator-api.md)
- [PDF linearization API](/guides/dws-processor/tools-and-api/pdf-linearization-api.md)
- [PDF rotate API](/guides/dws-processor/tools-and-api/pdf-rotate-api.md)
- [PDF security API](/guides/dws-processor/tools-and-api/pdf-security-api.md)
- [PDF page manipulation API](/guides/dws-processor/tools-and-api/pdf-page-manipulation-api.md)
- [PDF split API](/guides/dws-processor/tools-and-api/pdf-split-api.md)
- [PDF-to-HTML API](/guides/dws-processor/tools-and-api/pdf-to-html-api.md)
- [PDF-to-image API](/guides/dws-processor/tools-and-api/pdf-to-image-api.md)
- [PDF-to-Markdown API](/guides/dws-processor/tools-and-api/pdf-to-markdown-api.md)
- [PDF-to-Office API](/guides/dws-processor/tools-and-api/pdf-to-office-api.md)
- [PDF-to-PDF/A API](/guides/dws-processor/tools-and-api/pdf-to-pdfa-api.md)
- [PDF watermark API](/guides/dws-processor/tools-and-api/pdf-watermark-api.md)
- [Redaction API](/guides/dws-processor/tools-and-api/redaction-api.md)
- [PDF/UA auto-tagging API](/guides/dws-processor/tools-and-api/pdfua-api.md)