Merging PDFs in the browser with pdf-lib (no server upload)
Most online PDF mergers upload your file to a server. For sensitive documents, that’s a problem. Approach Use pdf-lib in the browser: Read files with File.arrayBuffer() PDFDocument.load() each source copyPages() into a new PDFDocument save() and download via a Blob URL The PDF never needs to leave the user’s device for this flow. Verify privacy Open DevTools → Network, merge a test PDF, and confirm there’s no upload request carrying the file body. After the app loads, you can even try offline. Try it I packaged this (merge, split, and more) in PDFCraftify: Merge tool: https://pdfcraftify.com/merge-pdf Guide: https://pdfcraftify.com/guides/merge-pdf-without-uploading Tradeoffs Browser memory limits very large jobs Password-protected PDFs must be unlocked first Not a replacement for full desktop DTP If you build similar tools, what edge cases bite you most? Comments welcome.