> 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/web/low-level-pdf-api.md). # Low-level PDF API - [Low-Level document editing (COS/SDF API) using Apryse's Web SDK](https://docs.apryse.com/web/low-level-pdf-api/low-level.md): Enhance your document editing capabilities with COS/SDF API using web. Access low-level PDF object model, integrate high and low-level APIs seamlessly, and unlock unique functionalities for customized - [Information dictionary: adding custom data to a PDF using JavaScript](https://docs.apryse.com/web/low-level-pdf-api/add-custom.md): Learn how to add custom data to an existing document using the Cos/SDF low-level API to edit PDF files. Get a full code sample demonstrating the use of basic Cos/SDF API for document editing. The Apry - [Introduction to PDF file format](https://docs.apryse.com/web/low-level-pdf-api/pdf.md): Discover the basic structure of a PDF document in this detailed guide. Learn about the header, body, cross-reference table, and trailer sections that make up a PDF file. Explore the elements that crea - [SDF / COS object model](https://docs.apryse.com/web/low-level-pdf-api/sdf.md): Discover the complexities of PDF documents and how Apryse CosEdit tool simplifies editing at the object level. Learn about SDF/COS object model and APIs for precise PDF manipulation. The Apryse Web SD - [Filters and streams using JavaScript](https://docs.apryse.com/web/low-level-pdf-api/filters.md): Learn about SDF stream objects and filter pipelines in PDF documents with Apryse SDK. Explore efficient data processing and extraction methods for better performance. The Apryse Web SDK streamlines se - [Sample for editing PDFs using basic Cos/SDF API using JavaScript](https://docs.apryse.com/web/low-level-pdf-api/samples.md): Learn how to edit PDF files using the Cos/SDF low-level API with this informative sample. Enhance your document editing skills now! The Apryse Web SDK streamlines secure, serverless document processin - [APIs for low-level PDF document editing using JavaScript](https://docs.apryse.com/web/low-level-pdf-api/apis.md): Discover utility classes for PDF documents with this low-level API. Explore Web (Javascript) PDFNet.Obj and PDFNet.SDFDoc functionalities. The Apryse Web SDK streamlines secure, serverless document pr --- # 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/web/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.