--- title: "How to manipulate PDF pages with pdf-lib: Extract, merge, and remove pages" canonical_url: "https://www.nutrient.io/blog/pdfjs-pdf-page-manipulation-pdf-lib/" md_url: "https://www.nutrient.io/blog/pdfjs-pdf-page-manipulation-pdf-lib.md" last_updated: "2026-07-14T18:00:17.434Z" description: "Learn how to use pdf-lib for PDF page manipulation in Node.js. This tutorial covers extracting pages, merging multiple PDFs, removing specific pages, and trimming documents for processing." --- **TL;DR** PDF.js reads and renders PDFs but can’t modify them structurally. Reach for `pdf-lib` when you need to: - Extract specific pages from a source PDF. - Merge multiple PDFs into one. - Remove pages by index. - Trim a PDF to the first N pages before uploading to a processing service. The core API is `PDFDocument.load()` → `copyPages()` → `addPage()` → `save()`. Page indices are zero-based, and `pdf-lib` works in both Node.js and the browser with no external workers or fonts. [Nutrient Web SDK](https://www.nutrient.io/sdk/web-overview/) handles the same operations client-side via the `applyOperations` API. PDF.js reads and renders PDFs but doesn’t modify them structurally. For operations like extracting pages, merging documents, or trimming PDFs, use `pdf-lib`. ## Install Install `pdf-lib` with npm: ```bash npm install pdf-lib ``` ## Copying specific pages Extract the first N pages from a PDF — useful for sending a preview to a processing service: ```tsx import { PDFDocument } from "pdf-lib"; async function copyFirstTwoPages(pdfBuffer) { const originalPdf = await PDFDocument.load(pdfBuffer); const pageCount = originalPdf.getPageCount(); if (pageCount === 0) { throw new Error("The PDF has no pages."); } const newPdf = await PDFDocument.create(); const indices = originalPdf.getPageIndices().slice(0, 2); const pages = await newPdf.copyPages(originalPdf, indices); pages.forEach((page) => newPdf.addPage(page)); return Buffer.from(await newPdf.save()); } ``` ## Key concepts The core `PDFDocument` API covers three building blocks: loading, creating, and copying pages. ### Loading a PDF `PDFDocument.load()` accepts a `Buffer`, `Uint8Array`, or base64 string and returns a `PDFDocument` instance: ```tsx // From Buffer. const pdf = await PDFDocument.load(buffer); // From Uint8Array. const pdf = await PDFDocument.load(uint8Array); // From base64 string. const pdf = await PDFDocument.load(base64String); ``` ### Creating a new PDF Use `PDFDocument.create()` to start a new, empty document that you can populate with pages copied from existing PDFs: ```tsx const newPdf = await PDFDocument.create(); ``` ### Copying pages between documents `copyPages` copies pages from a source document into a destination document. It returns page objects that you then add: ```tsx // Copy pages at indices 0, 2, 4 from source. const copiedPages = await destPdf.copyPages(sourcePdf, [0, 2, 4]); // Add them to the destination. for (const page of copiedPages) { destPdf.addPage(page); } ``` ### Saving `save()` serializes the document back to bytes. The return value is a `Uint8Array`, which you can convert to a Node.js `Buffer` for writing to disk, passing to an HTTP response, or uploading to storage: ```tsx const bytes = await pdf.save(); // Returns Uint8Array. const buffer = Buffer.from(bytes); // Convert to Node.js Buffer. ``` ## Use case: Trim a PDF before processing Some services (like GROBID for academic metadata extraction) only need the first few pages. Sending a trimmed PDF is faster and avoids upload size limits: ```tsx async function trimForProcessing(pdfBuffer, maxPages = 2) { const original = await PDFDocument.load(pdfBuffer); const pageCount = original.getPageCount(); const pagesToCopy = Math.min(pageCount, maxPages); const trimmed = await PDFDocument.create(); const indices = Array.from({ length: pagesToCopy }, (_, i) => i); const pages = await trimmed.copyPages(original, indices); for (const page of pages) { trimmed.addPage(page); } return Buffer.from(await trimmed.save()); } ``` ## Use case: Merge multiple PDFs Loop over an array of buffers, copying all pages from each source into a single output document: ```tsx async function mergePdfs(pdfBuffers) { const merged = await PDFDocument.create(); for (const buffer of pdfBuffers) { const source = await PDFDocument.load(buffer); const indices = source.getPageIndices(); // [0, 1, 2,...] const pages = await merged.copyPages(source, indices); for (const page of pages) { merged.addPage(page); } } return Buffer.from(await merged.save()); } ``` ## Use case: Remove specific pages Filter the page indices to exclude the ones you want to remove. Then copy the rest into a new document: ```tsx async function removePages(pdfBuffer, pagesToRemove) { const original = await PDFDocument.load(pdfBuffer); const allIndices = original.getPageIndices(); const keepIndices = allIndices.filter((i) =>!pagesToRemove.includes(i)); const result = await PDFDocument.create(); const pages = await result.copyPages(original, keepIndices); for (const page of pages) { result.addPage(page); } return Buffer.from(await result.save()); } ``` ## pdf-lib vs. PDF.js | Operation | pdf-lib | PDF.js | | ------------------- | ------- | ------------------------- | | Read text content | No | Yes (`getTextContent`) | | Render pages | No | Yes (`PDFViewer`, canvas) | | Copy/move pages | Yes | No | | Create new PDFs | Yes | No | | Modify PDF metadata | Yes | No | | Add form fields | Yes | No | | Embed images/fonts | Yes | No | Use PDF.js for reading and rendering. Use pdf-lib for creating and modifying. ## Key points - `pdf-lib` works in both Node.js and the browser. - `copyPages` is the core method — it copies pages between documents. - Always call `addPage` after `copyPages` — copied pages aren’t automatically added. - `save()` returns a `Uint8Array`; convert with `Buffer.from()` for Node.js. - Page indices are zero-based. - `pdf-lib` doesn’t need any external fonts, workers, or CMaps. ## FAQ #### Why can’t PDF.js modify PDFs? PDF.js is a parser and renderer, not a writer. It opens and displays PDFs but has no API to create, modify, or save them. For structural changes — adding, removing, reordering, or merging pages — you need a library like `pdf-lib` or `pdfkit`, or a commercial SDK with editing support. #### Does pdf-lib work in the browser? Yes. `pdf-lib` is pure JavaScript with no native dependencies, so it runs in Node.js and the browser. In the browser, load PDFs from a `File`, `Blob`, or `Uint8Array` instead of a `Buffer`, and use `Blob`/`URL.createObjectURL` to deliver the saved output for download. #### Why do I need addPage after copyPages? `copyPages` returns an array of `PDFPage` objects that have been deep-copied from the source document into the destination, but they aren’t inserted into the destination’s page tree until you call `addPage` (or `insertPage`). This two-step design lets you copy pages once and reorder them freely before committing. #### How do I convert pdf-lib’s output to a Node.js Buffer? `pdfDocument.save()` returns a `Uint8Array`. Wrap it with `Buffer.from()` to get a Node.js `Buffer` for `fs.writeFile`, HTTP responses, or S3 uploads: `const buffer = Buffer.from(await pdf.save())`. #### Can pdf-lib render or display PDFs? No. `pdf-lib` builds and modifies PDFs but doesn’t render them. Pair it with PDF.js (for viewing) or a commercial viewer SDK when you need both editing and display. #### How does Nutrient Web SDK compare? Nutrient handles add, remove, merge, split, rotate, and reorder operations client-side through `instance.applyOperations()` and exports the result with `instance.exportPDF()`. There’s no separate library to install, no manual `copyPages` and `addPage` loops, and the same operations apply to a live viewer. See the [page manipulation](https://www.nutrient.io/guides/web/editor/add-page.md) guide for details. ## How Nutrient Web SDK handles this Nutrient Web SDK handles page manipulation directly in the browser with the `applyOperations` API — no `pdf-lib` dependency, no manual page copying, and no `addPage()` loops: ```js // Add a blank page after page 1. instance.applyOperations([ { type: "addPage", afterPageIndex: 1, backgroundColor: new NutrientViewer.Color({ r: 255, g: 255, b: 255 }), pageWidth: 595, pageHeight: 842, }, ]); // Remove a page. instance.applyOperations([{ type: "removePage", pageIndex: 3 }]); // Export the modified PDF. const buffer = await instance.exportPDF(); ``` Nutrient also supports merging, splitting, rotating, cropping, and reordering — all client-side. --- _See [Nutrient Web SDK](https://www.nutrient.io/sdk/web-overview/) for an alternative to PDF.js and `pdf-lib`. The [page manipulation](https://www.nutrient.io/guides/web/editor/add-page.md) and [save/export](https://www.nutrient.io/guides/web/save-a-document/to-arraybuffer.md) guides cover the API in depth. Follow the [migration guide](https://www.nutrient.io/guides/web/about/migration-guides/migrating-from-mozilla-pdfjs.md) to switch, or [talk to Sales](https://www.nutrient.io/contact-sales/?=sdk) about your requirements._ --- ## Related pages - [The business case for accessibility: Five ways it drives enterprise value](/blog/5-ways-accessibility-drives-enterprise-value.md) - [Accessibility Untangled Why It Matters Guide](/blog/accessibility-untangled-why-it-matters-guide.md) - [Advanced Techniques For React Native Ui Components](/blog/advanced-techniques-for-react-native-ui-components.md) - [Ai Document Automation Extraction To Action](/blog/ai-document-automation-extraction-to-action.md) - [Ai Legal Assistant Document Authoring](/blog/ai-legal-assistant-document-authoring.md) - [Angular File Viewer Pdf Image Office Files](/blog/angular-file-viewer-pdf-image-office-files.md) - [Auto Tagging And Document Accessibility In Dotnet Sdk](/blog/auto-tagging-and-document-accessibility-in-dotnet-sdk.md) - 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