Wrenlio
PDF Tools

Merge PDF Files

Combine multiple PDF files into a single document in your browser, with drag-to-reorder before merging.

Click to choose PDFs, or drag and drop

Add two or more files, in any order

Merging happens entirely in your browser. Your files are never uploaded to a server.

About this tool

Combining PDFs — a scanned form and a cover letter, or several chapters of a report — usually means installing desktop software or trusting a third-party upload service. This tool merges PDF files directly in your browser using pdf-lib, an open-source PDF library, so your documents never leave your device.

How to use it

  1. 1Click the upload area or drag two or more PDF files onto it.
  2. 2Reorder files using the up and down arrows — they'll be merged in the order shown.
  3. 3Click "Merge PDFs" to combine them into a single document.
  4. 4Download the merged PDF.

Common mistakes to avoid

  • Trying to merge a password-protected or encrypted PDF, which will fail until it's unlocked first.
  • Forgetting to reorder files before merging, resulting in pages in the wrong sequence.
  • Assuming form fields or interactive elements always survive a merge — complex PDF features can behave differently after combining.

Use cases

  • Combining a cover letter, resume, and portfolio into a single PDF for a job application.
  • Merging scanned pages into one document.
  • Assembling multiple reports or invoices into a single file to send.

Frequently asked questions

Are my PDFs uploaded to a server?

No. Merging is done entirely in your browser using pdf-lib, an open-source JavaScript library. Your files never leave your device.

Is there a limit to how many PDFs I can merge?

There's no hard-coded limit, but very large files or a large number of files may be limited by your browser's available memory.

Can I merge password-protected PDFs?

Not directly. Remove the password protection from each file first using a PDF editor, then merge them here.

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