Modern web applications often need more than just PDF viewing—they require the ability to modify documents directly. With WebViewer’s JavaScript PDF library, developers can perform powerful PDF page manipulations entirely on the client side.

Modify PDF Files Without a Server

When running in client-only mode, WebViewer can make permanent changes to PDF documents, including:

• Inserting pages
• Deleting pages
• Rotating pages
• Cropping pages
• Reordering pages
• Splitting PDFs
• Merging multiple PDFs

Unlike temporary viewer adjustments, these changes are applied directly to the PDF data. When users download the file or export it using getFileData(), the modified document can be opened in any PDF viewer with all changes preserved.

Quick Example: Rotate a PDF Page

With just a few lines of code, you can rotate a page in a PDF document:

WebViewer({
  path: '/webviewer/lib',
  initialDoc: '/files/sample.pdf'
}, document.getElementById('viewer')).then(async (instance) => {
  const { documentViewer } = instance.Core;

  documentViewer.addEventListener('documentLoaded', async () => {
    const doc = documentViewer.getDocument();

    // Rotate page 1 by 90 degrees
    await doc.rotatePages([1], 90);

    // Export the updated PDF
    const data = await doc.getFileData();
  });
});

The updated PDF will retain the page rotation when downloaded or opened in another PDF viewer.

Key Benefits

WebViewer enables a wide range of document assembly and editing workflows:

• Split and combine PDF documents
• Merge and append pages from multiple files
• Replicate and reorder pages
• Create new documents from existing PDFs
• Remove unwanted pages
• Crop, rotate, and resize pages
• Adjust media, crop, and bleed boxes
• Reposition page content
• Manage PDF page labels
• Edit PDF text directly (experimental)

Working with Office Documents

Page manipulation features are designed for PDFs. If you’re working with Office files such as DOCX, XLSX, or PPTX, enable the loadAsPDF: true option to automatically convert them to PDF before editing.

For WebViewer Server deployments, use forceClientSideInit: true to switch processing to the client and enable page manipulation capabilities.

Common Use Cases

PDF page manipulation is ideal for:

• Document assembly workflows
• Report generation
• Contract management
• Digital publishing
• Batch PDF processing
• Custom document editing applications