--- title: "Convert DOCX, EPUB, Markdown, and HTML to PDF in Node.js" canonical_url: "https://www.nutrient.io/blog/pdfjs-file-format-conversion-to-pdf/" md_url: "https://www.nutrient.io/blog/pdfjs-file-format-conversion-to-pdf.md" last_updated: "2026-08-11T20:47:43.241Z" description: "Convert DOCX, EPUB, Markdown, and HTML to PDF in Node.js with LibreOffice, Calibre, md-to-pdf, Puppeteer, and ocrmypdf for scanned documents." --- **TL;DR** - LibreOffice (via `libreoffice-convert`) handles DOCX, XLSX, PPTX, RTF, TXT, and other Office formats. - Calibre’s `ebook-convert` handles EPUB, MOBI, and AZW3; `md-to-pdf` handles Markdown; Puppeteer’s `page.pdf()` handles HTML/webpages. - After conversion, run `ocrmypdf` over scanned pages to make them searchable. Pipe everything together in one upload handler. ## Prerequisites This guide is server-side — you’ll need Node.js and the ability to install system packages. The pipeline reads/writes temporary files, so the process needs write access to `os.tmpdir()`. You’ll also need: - Node.js 18 or later - LibreOffice, Calibre, and ocrmypdf installed (see each tool’s section below) - The npm packages `libreoffice-convert`, `md-to-pdf`, `puppeteer`, and `uuid` A PDF viewer only handles PDFs — but users upload Word documents, EPUBs, PowerPoints, and more. This guide covers the ecosystem of tools for converting different formats to PDF on the server. ## Overview of conversion tools | Format | Tool | Type | | -------------------------- | ------------------------- | ----------- | | DOCX, XLSX, PPTX, RTF, TXT | LibreOffice (headless) | System CLI | | EPUB, MOBI, AZW3 | Calibre (`ebook-convert`) | System CLI | | Markdown | `md-to-pdf` | npm package | | HTML/webpages | Puppeteer (`page.pdf()`) | npm package | ## LibreOffice: Office documents to PDF LibreOffice handles the widest range of Office formats through a single headless CLI call. ### Setup Install LibreOffice on the target platform: ```bash # macOS brew install --cask libreoffice # Ubuntu/Debian sudo apt-get install libreoffice # Docker FROM node:20 RUN apt-get update && apt-get install -y libreoffice ``` ### Usage with libreoffice-convert Install the npm wrapper. Then convert a buffer to PDF: ```bash npm install libreoffice-convert ``` ```tsx import libre from "libreoffice-convert"; import { promisify } from "util"; const convertAsync = promisify(libre.convert); async function officeToPdf(inputBuffer) { const pdfBuffer = await convertAsync(inputBuffer, ".pdf", undefined); return pdfBuffer; } ``` Supported input formats include: `.doc`, `.docx`, `.xls`, `.xlsx`, `.ppt`, `.pptx`, `.odt`, `.ods`, `.odp`, `.rtf`, and `.txt`. ## Calibre: eBooks to PDF Calibre’s `ebook-convert` CLI handles eBook formats that LibreOffice doesn’t, and it can also extract metadata from eBooks and PDFs. ### Setup Install Calibre on the target platform: ```bash # macOS brew install --cask calibre # Ubuntu/Debian sudo apt-get install calibre ``` ### Usage Convert an eBook buffer to PDF by shelling out to Calibre’s `ebook-convert` CLI: ```tsx import { exec } from "child_process"; import { promisify } from "util"; import { writeFile, readFile, unlink } from "fs/promises"; import { join } from "path"; import { tmpdir } from "os"; import { v4 as uuid } from "uuid"; const execAsync = promisify(exec); async function ebookToPdf(inputBuffer, inputExtension) { const inputPath = join(tmpdir(), `${uuid()}${inputExtension}`); const outputPath = join(tmpdir(), `${uuid()}.pdf`); try { await writeFile(inputPath, inputBuffer); await execAsync(`ebook-convert "${inputPath}" "${outputPath}"`); return await readFile(outputPath); } finally { await unlink(inputPath).catch(() => {}); await unlink(outputPath).catch(() => {}); } } ``` ### Extracting metadata Calibre also extracts metadata from eBooks and PDFs: ```tsx async function getMetadata(inputBuffer, mimeType) { const ext = mimeToExtension(mimeType); // e.g. ".epub", ".pdf". const inputPath = join(tmpdir(), `${uuid()}${ext}`); try { await writeFile(inputPath, inputBuffer); const { stdout } = await execAsync(`ebook-meta "${inputPath}"`); return parseMetadataOutput(stdout); } finally { await unlink(inputPath).catch(() => {}); } } ``` ## md-to-pdf: Markdown to PDF Install the package: ```bash npm install md-to-pdf ``` ```tsx import { mdToPdf } from "md-to-pdf"; async function markdownToPdf(markdownBuffer) { const markdownString = markdownBuffer.toString("utf-8"); const result = await mdToPdf({ content: markdownString }); return result?.content; // PDF as `Buffer`. } ``` `md-to-pdf` uses Puppeteer under the hood — it renders the Markdown as HTML and prints to PDF. ## Puppeteer: Webpages to PDF Install Puppeteer: ```bash npm install puppeteer ``` ```tsx import puppeteer from "puppeteer"; async function webPageToPdf(url) { const browser = await puppeteer.launch({ headless: true }); const page = await browser.newPage(); await page.goto(url, { waitUntil: "networkidle2" }); const pdfBuffer = await page.pdf({ format: "A4", printBackground: true, margin: { top: "20mm", right: "20mm", bottom: "20mm", left: "20mm", }, }); await browser.close(); return pdfBuffer; } ``` ### Puppeteer tips - Use `waitUntil: "networkidle2"` to wait for dynamic content. - Set `printBackground: true` to include background colors/images. - Consider ad blocking and cookie consent handling for web scraping use cases. ## OCR: Making scanned PDFs searchable After detecting that a PDF needs OCR (see the [server-side text extraction tutorial](https://www.nutrient.io/blog/pdfjs-server-side-text-extraction.md)), use `ocrmypdf`: ```bash # Install sudo apt-get install ocrmypdf # macOS brew install ocrmypdf ``` ```tsx async function ocrPdf(pdfBuffer, language = "eng") { const inputPath = join(tmpdir(), `${uuid()}.pdf`); const outputPath = join(tmpdir(), `${uuid()}.pdf`); try { await writeFile(inputPath, pdfBuffer); await execAsync( `ocrmypdf -l ${language} --skip-text --output-type pdf -q "${inputPath}" "${outputPath}"`, ); return await readFile(outputPath); } finally { await unlink(inputPath).catch(() => {}); await unlink(outputPath).catch(() => {}); } } ``` Options: - `-l eng` — OCR language. - `--skip-text` — Skip pages that already have text (don’t re-OCR). - `--output-type pdf` — Output standard PDF (not PDF/A). - `-q` — Quiet mode. ## Complete processing pipeline The pipeline below ties everything together. The helpers `isOfficeFormat`, `isEbookFormat`, `mimeToExtension`, `checkPdf`, `generatePreview`, and `extractText` are reader-implemented — `checkPdf` and `extractText` are covered in [server-side text extraction](https://www.nutrient.io/blog/pdfjs-server-side-text-extraction.md), and `generatePreview` can be built with [pdf2pic](https://www.nutrient.io/blog/pdfjs-generating-pdf-thumbnails-pdf2pic.md). ```tsx async function processUpload(buffer, filename, mimeType) { let pdfBuffer; // Step 1: Convert to PDF if needed. if (mimeType === "application/pdf") { pdfBuffer = buffer; } else if (isOfficeFormat(mimeType)) { pdfBuffer = await officeToPdf(buffer); } else if (isEbookFormat(mimeType)) { pdfBuffer = await ebookToPdf(buffer, mimeToExtension(mimeType)); } else if (mimeType === "text/markdown") { pdfBuffer = await markdownToPdf(buffer); } // Step 2: Check if OCR is needed. const { pages, needsOcr } = await checkPdf(pdfBuffer); // Step 3: Run OCR if needed. if (needsOcr) { pdfBuffer = await ocrPdf(pdfBuffer); } // Step 4: Generate preview thumbnail. const preview = await generatePreview(pdfBuffer); // Step 5: Extract text for indexing. const text = await extractText(pdfBuffer); return { pdfBuffer, preview, text, pages }; } ``` ## Key points - LibreOffice handles most Office formats but requires a system installation. - Calibre handles eBook formats (EPUB, MOBI) and metadata extraction. - `md-to-pdf` is the simplest Markdown converter (uses Puppeteer internally). - Puppeteer’s `page.pdf()` captures any webpage as a perfectly rendered PDF. - `ocrmypdf` adds searchable text to scanned PDFs without changing the visual content. - Always clean up temporary files in `finally` blocks. - Most CLI tools need temporary file I/O — write buffer to disk, convert, read result, delete both. ## How Nutrient Web SDK handles conversion and OCR Nutrient Web SDK converts Office documents to PDF directly in the browser and runs OCR on scanned PDFs through the same instance — no LibreOffice, Calibre, Puppeteer, or temporary file plumbing on the server is necessary. ```js const instance = await NutrientViewer.load({ container: "#pdf-container", document: "report.docx", // Word, Excel, and PowerPoint are all supported. }); await instance.applyOperations([ { type: "performOcr", language: "english", pageIndexes: "all" }, ]); ``` Supported input formats include Word, Excel, PowerPoint, TIFF, JPG, and PNG — all converted client-side without an MS Office license. For server-side workflows, [Nutrient Document Engine](https://www.nutrient.io/sdk/document-engine/) exposes the same conversion and OCR through a REST API. [Learn more about Nutrient Web SDK](https://www.nutrient.io/sdk/web-overview/) | [Conversion guide](https://www.nutrient.io/guides/web/conversion.md) | [OCR guide](https://www.nutrient.io/guides/web/ocr.md) | [Migration guide](https://www.nutrient.io/guides/web/about/migration-guides/migrating-from-mozilla-pdfjs.md) | [Contact Sales](https://www.nutrient.io/contact-sales/?=sdk) ## FAQ #### Why not run LibreOffice from a CDN or browser? LibreOffice is a desktop application that needs file-system access, a Java runtime, and ~300 MB of disk space. There’s no browser-shippable version. Conversion has to happen on a server (or in a desktop/Electron app); the browser-only options for Office documents are commercial libraries or REST APIs. #### What’s the difference between --skip-text and --force-ocr in ocrmypdf? `--skip-text` leaves pages that already contain a text layer alone — safe for mixed batches. `--force-ocr` re-OCRs every page, overwriting any existing text layer. Use `--skip-text` by default; switch to `--force-ocr` only when you suspect the existing text layer is wrong (poor, old OCR or corrupted text). They’re mutually exclusive. #### How do I detect whether a PDF needs OCR? Extract a text sample from the first few pages with `pdfDocument.getPage(i).getTextContent()`. If the total characters are below a threshold (say 50 across the sampled pages), the PDF is likely image-only and needs OCR. See the [server-side text extraction post](https://www.nutrient.io/blog/pdfjs-server-side-text-extraction.md) for a full implementation. #### What’s headless: true actually doing under the hood? In current Puppeteer (v22+), `headless: true` runs Chromium’s native headless mode, which renders pages closer to what a real user would see in a visible browser — important for PDFs of complex layouts. The legacy `chrome-headless-shell` binary is still available via `headless: 'shell'` for faster startup at the cost of fidelity. The `"new"` string used in older guides has been removed. #### Can I run LibreOffice and Calibre in a Docker container? Yes. The example `FROM node:20` Dockerfile shows the LibreOffice setup. For Calibre, install with `apt-get install -y calibre` — note the image will be ~1 GB larger. For production, use a multistage build that copies only the binaries needed, or split conversion into a dedicated microservice. #### What about converting PDF to other formats? Reverse conversion (PDF to DOCX, HTML, images) is harder to do well because text layout reconstruction is brittle. LibreOffice supports PDF → DOCX with mixed results; Calibre handles PDF → EPUB. For high-fidelity output, commercial tools (including Nutrient’s [conversion API](https://www.nutrient.io/guides/web/conversion.md)) generally beat the open source options. --- ## 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) - [`vector_store` holds your indexed documents (see the multimodal RAG post](/blog/agentic-rag.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) - [Best Document Ai Platforms](/blog/best-document-ai-platforms.md) - [Best Document Viewers](/blog/best-document-viewers.md) - [The CEO’s AI playbook: Why decision architecture beats model selection](/blog/ceo-ai-playbook-decision-architecture.md) - [1. 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