> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/core/low-level-pdf-api.md). # Low-level PDF API - [Low-Level document editing (COS/SDF API) on Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/low-level.md): Discover the benefits of working with low-level PDF APIs using Apryse SDK. Gain full access to COS/SDF object model, seamless integration, and unique functionalities for customizing PDF documents. Sta - [Information dictionary: adding custom data to a PDF on Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/add-custom.md): Learn how to add custom data to existing PDF documents using the Cos/SDF low-level API. Get a full code sample demonstrating how to edit PDF files efficiently. The Apryse Server SDK streamlines secure - [PDF File Format in Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/pdf.md): Discover the basic structure of a PDF document and how it functions. Learn about the header, body, cross-reference table, and trailer sections that make up a PDF file. Explore the "Hello World" sample - [SDF / COS object model](https://docs.apryse.com/core/low-level-pdf-api/sdf.md): Discover the complexities of PDF documents and how to edit them with ease using Apryse CosEdit. Explore the low-level object model of PDFs and unlock unprecedented control over your files. The Apryse - [Filters and streams on Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/filters.md): Learn about SDF stream objects and filter pipelines in PDF documents with Apryse SDK. Explore how to efficiently process streams using various filters for data transformation and extraction. The Aprys - [Sample for editing PDFs using basic Cos/SDF API on Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/samples.md): Unlock the power of Cos/SDF low-level API to edit PDF files with this informative sample. Learn how to enhance your existing documents effortlessly. The Apryse Server SDK streamlines secure document p - [APIs for low-level PDF document editing on Server/Desktop](https://docs.apryse.com/core/low-level-pdf-api/apis.md): Discover utility classes for PDF documents in C++, Java, Web (Javascript), Node.js, .NET, .NET Core, iOS, Xamarin.Android, Xamarin.iOS, and UWP with PDFNet API. Optimize your PDF handling now! The Apr --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.apryse.com/core/low-level-pdf-api.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.