---
title: "PDF annotation server — Markup, highlight, comment | Nutrient"
canonical_url: "https://www.nutrient.io/guides/document-engine/annotations/"
md_url: "https://www.nutrient.io/guides/document-engine/annotations.md"
last_updated: "2026-06-09T10:25:14.392Z"
description: "Unleash the power of annotations with our comprehensive guide. Learn how to enhance your documents with expert tips and strategies. Unlock the possibilities now!"
---

# PDF annotation server

Document Engine includes support for importing, creating, removing, and flattening PDF annotations. It offers developers a robust API for programmatic annotation management, as well as integration with our client-side SDKs for manual annotation through a UI.

## What are annotations?

Content displayed as a PDF page isn’t suitable for easy editing, but the PDF specification defines a comprehensive set of objects that can be added to PDF pages without changing the page content. These objects are called annotations, and their purpose ranges from marking up page content to implementing interactive features such as forms.

[Learn more](https://www.nutrient.io/guides/document-engine/annotations/introduction-to-annotations/what-are-annotations.md)

## Essential guides

---

**Supported annotation types**

Learn about the types of annotations supported by Nutrient

[Read more](https://www.nutrient.io/guides/document-engine/annotations/introduction-to-annotations/annotation-types.md)

---

**Annotation data formats**

Learn about using external files to manage annotations

[Read more](https://www.nutrient.io/guides/document-engine/annotations/introduction-to-annotations/data-formats.md)

---

**Architecture diagram**

Learn how edits to annotations flow to and from a client

[Read more](https://www.nutrient.io/guides/document-engine/annotations/architecture-diagram.md)

---

**Flatten annotations**

How to flatten annotations and burn them into a PDF

[Read more](https://www.nutrient.io/guides/document-engine/annotations/flatten.md)

---

**Annotate on images**

Learn how PNGs, JPGs, TIFFs, and more are annotated

[Read more](https://www.nutrient.io/guides/document-engine/annotations/annotate-on-images.md)

## Import and export

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**To/from XFDF**

How to import/export annotations to/from XFDF

[Read more](https://www.nutrient.io/guides/document-engine/annotations/import-and-export/xfdf.md)

---

**To/from Instant JSON**

How to import/export annotations to/from Instant JSON

[Read more](https://www.nutrient.io/guides/document-engine/annotations/import-and-export/instant-json.md)

**Call to Action**

Start your free trial for unlimited access and expert support.

[Learn More](https://www.nutrient.io/sdk/document-engine/getting-started.md)

---

## Related pages

- [Annotate on images](/guides/document-engine/annotations/annotate-on-images.md)
- [Create](/guides/document-engine/annotations/create.md)
- [Architecture diagram](/guides/document-engine/annotations/architecture-diagram.md)
- [Edit](/guides/document-engine/annotations/edit.md)
- [Remove](/guides/document-engine/annotations/remove.md)
- [How to flatten PDF annotations effectively](/guides/document-engine/annotations/flatten.md)

## Pages in this section

- [Import and export Instant JSON PDF annotation data](/guides/document-engine/annotations/import-and-export/instant-json.md)
- [Import and export Instant XFDF PDF annotation data](/guides/document-engine/annotations/import-and-export/xfdf.md)
- [Understanding PDF annotations and their types](/guides/document-engine/annotations/introduction-to-annotations/what-are-annotations.md)
- [Supported annotation types](/guides/document-engine/annotations/introduction-to-annotations/annotation-types.md)
- [Understand annotation data formats for PDFs](/guides/document-engine/annotations/introduction-to-annotations/data-formats.md)