# Store user-uploaded files

When you want to store a file uploaded by an end user, the file needs to be uploaded to your service first, and then forwarded to Document Engine.![Document Engine is used to store PDF documents and their annotations. Your server has access to a rich HTTP API.](@/assets/guides/document-engine/store-user-uploaded-files.png)

1. A user uploads a document to your backend.

2. Your backend forwards the uploaded PDF file to Document Engine. In return, it receives a document identifier. On your Document Engine, you only have to store the identifier; we store the PDF document, its annotations, and the meta information. Document files are stored in the asset storage, which can be one of the supported [asset storage backends](https://www.nutrient.io/../../configuration/asset-storage/).
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## Related pages

- [Create a document from an upload](/guides/document-engine/file-management/create-a-document-from-upload.md)
- [Create a document from a URL](/guides/document-engine/file-management/create-a-document-from-url.md)
- [List documents with pagination](/guides/document-engine/file-management/list-documents.md)
- [Remove files](/guides/document-engine/file-management/remove.md)
- [File management overview](/guides/document-engine/file-management.md)
- [Working with password-protected PDFs](/guides/document-engine/file-management/password-pdfs.md)