Lite Tools

PDF Merge

Combine multiple PDF files into a single PDF online. Files are processed entirely in your browser: nothing is ever uploaded to a server.

Click to select or drag PDF files here Pick several PDFs at once: they sort by name, and you can reorder them below

How to use

  1. Click the drop zone or drag PDF files into it (you can select several at once).
  2. Use the "Move up / Move down" buttons on each item to change the order.
  3. Click "Merge PDFs" to combine the files in the listed order into one PDF.
  4. The result downloads automatically. Everything happens locally: no upload needed.

FAQ

Will my pages lose quality after merging?
No. This tool copies pages as-is without re-compressing or re-encoding them, so the merged output matches the original files exactly.
Are my files uploaded anywhere?
No. Merging runs entirely inside your browser (powered by the open-source pdf-lib library). Your PDFs never leave your device.
Is there a file limit?
No fixed limit, but browser memory applies. For the best speed and stability we recommend merging no more than 20 files under about 200MB total at once.

Screenshots

PDF Merge · Interface
Interface

How to use

  1. Add your PDF files

    Click the drop zone or drag several PDFs in at once. Newly added files are sorted by name, and every file appears as a card in the list below.

  2. Set the merge order

    Use the move up and move down buttons until the list matches the final page order.

  3. Click Merge PDFs

    The tool copies every page with pdf-lib inside your browser and builds one new file. Pages are not re-encoded, so quality stays identical to the originals.

  4. Save the downloaded result

    When merging finishes, the combined PDF downloads automatically. Large batches take a few seconds, so keep the tab open until the download starts.

About this tool

PDF Merge combines several PDF documents into one, in the exact order you choose. The merging runs entirely in your browser through the open-source pdf-lib library. Each page is copied as-is into a fresh document, with no re-compression or re-rendering. Text stays selectable and image quality is untouched, because the pages are never rebuilt. Nothing is uploaded to a server, so confidential contracts, medical records or invoices can be processed on any device.

It suits anyone who needs one tidy file instead of many. Students combine a cover sheet with an essay. Freelancers merge invoices and receipts. HR teams assemble signed forms. Batch scans turn into a single archive. There is no fixed file limit, so it also handles weekly reports stitched into a monthly record. For the best speed and stability, keep a session to about 20 files or 200 MB total.

How it works

A PDF file is not a stack of pictures. It is a tree of numbered objects. A document catalog points to a page tree, and each page node references a content stream plus shared resources such as font subsets and images. Two source files can easily reuse the same object numbers, and splicing them directly would make those objects overwrite each other. Merging re-parents page objects under one new tree. When pdf-lib copies a page, it clones the resources that page references and remaps the object numbers, so pages from two files never collide. The merged file opens on its own, and deleting the originals does not affect it.

Copying happens at the page level. Page content, rotation flags and most annotations survive untouched. Pages are copied as they are with no re-encoding, so text stays selectable and image quality is unchanged. Document-level structures behave differently: bookmark outlines, fillable form fields and digital signatures usually do not migrate with the pages. The output also drops linearization (Fast Web View). Over a network, the first open can feel slightly slower than the original. Local reading shows no difference.

When to use it

  1. Monthly invoice archiving

    Name invoices from banks, travel sites and shops with a date and a number, then merge each month into one accounting attachment. Reconciliation then opens a single ordered file instead of a download folder full of loose PDFs.

  2. Rescanning a missed page

    Missed a page in a long scan? Scan just that page, slot it into position with the move buttons and merge again. The document is whole in minutes, and the rest of the pages stay untouched.

  3. Handout bundles for class

    Teachers merge lecture notes, exercises and answer keys in teaching order into one PDF for the class group. Students download a single file, and the printed page order matches the course.

Tips & tricks

  • Prepend 01, 02 and 03 to file names before adding them, so the automatic name sort already matches the order you want.
  • Pages are copied as-is, so encrypted or corrupted source files may fail; decrypt such PDFs first, then merge them.
  • There is no hard limit, but browser memory applies. Keep each session around 20 files or 200 MB for the smoothest runs.

Things to watch

  • Form fields and signatures break

    Fillable forms and digital signatures live at the document level and often stop working after a merge. For contracts, assemble the pages first and run the signing flow afterwards. Doing it in reverse can void the signature.

  • Page sizes are not unified

    Every page keeps its original dimensions, so A4 and A3 or portrait and landscape can coexist in one file. Pick fit-to-page in the print dialog so smaller pages are not enlarged and cropped.

  • Bookmarks do not travel

    Sidebar bookmarks belong to the document, not to the pages, and they disappear in the merged copy. For long manuals, rebuild the outline afterwards, or keep a contents page inside the document.

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