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How to merge PDFs for free in 2026: complete guide

Merge two PDFs, combine multiple invoices, assemble a portfolio: 4 free methods compared (online, browser, local software, command line).

May 06, 20265 min readBy PDFly

You have several PDFs to combine into one. Whether you're putting together a job application, grouping invoices for accounting, or stitching report chapters, PDF merging is one of the most common operations — and fortunately one of the easiest to do without paid software.

Here are the 4 main methods, compared in 2026 on privacy, speed, and limits.

Method 1: Online in the browser (no server upload)

This is the fastest method for most users. The key word: in the browser, not just "online."

The difference? Modern services use JavaScript libraries (like pdf-lib) that do everything locally in your browser. Your files are never sent to a remote server.

How to do it with PDFly

  1. Go to pdfly.eu/en/tools/merge
  2. Drag and drop your PDFs into the zone (or click "Choose files")
  3. Reorder via drag-and-drop if needed
  4. Click "Merge"
  5. The combined PDF downloads automatically

Duration: a few seconds for a handful of regular-sized files — it depends mostly on file size and on how powerful your device is.

Limits:

  • Files up to 100 MB each (enough for most cases)
  • Up to 50 files per merge
  • Requires a recent browser (Chrome, Safari, Firefox, Edge from 2022+)

These limits protect your browser: the merge happens in your tab's memory, and an oversized batch can freeze it — especially on a phone. Everything is free, with no sign-up and no daily cap.

Privacy: excellent — your PDFs don't leave your computer. You can verify it by opening the "Network" tab in your browser dev tools: no outgoing request with your file.

Browser or server: what to check before merging online

Many online PDF tools upload your files to their servers to merge them, then send the result back. For trivial PDFs, it's not a problem. For contracts or sensitive documents, it's better to know where they go.

Before choosing a tool, check:

  • Where files are processed: in the browser or on a server? Your browser dev tools' "Network" tab shows you.
  • If a server is used: in which country, under which law, and how long files are kept. The service's privacy policy and subprocessor list should say so.
  • Free-use limits: size per file, files per merge, tasks per day. They change over time: check them on the tool's website when you use it.
  • Sign-up, ads, watermark: are they required for a simple merge?

For PDFly, the answers are simple:

  • Processing in your browser: your files are sent to no server
  • Free, no sign-up, no ads, no watermark, no daily cap
  • Up to 100 MB per file and 50 files per merge
  • Website hosted in the European Union (Paris)

Method 2: Local software (PDFsam Basic)

If you regularly merge large PDFs (>100 MB) or work offline, local software is more suitable.

PDFsam Basic is an open-source reference, free, multiplatform (Windows, macOS, Linux). The interface is austere but effective.

Pros:

  • No size limit
  • 100% offline, open source
  • Multilingual

Cons:

  • Installation required (~80 MB)
  • Less modern interface
  • Manual updates

Method 3: Command line (advanced users)

If you're comfortable with a terminal, pdftk or qpdf are the reference tools.

# With pdftk
pdftk file1.pdf file2.pdf cat output merged.pdf

# With qpdf (modern, available in most Linux distributions)
qpdf --empty --pages file1.pdf file2.pdf -- merged.pdf

Pros:

  • Scriptable (perfect to automate a monthly invoice merge)
  • Very fast even on hundreds of files
  • No interface, no ads

Cons:

  • Reserved for technical users
  • Requires installation (brew install qpdf on macOS)

Method 4: Native features (macOS only)

On macOS, the built-in Preview app lets you merge two PDFs by dragging the thumbnails of one into the sidebar of the other, then File → Export as PDF.

It's slow for many files, but useful for 2-3 PDFs quickly, no internet needed.

Summary comparison

MethodSpeedPrivacyFile limitSkill required
PDFly (browser)Fast⭐⭐⭐⭐⭐100 MB per file / 50 filesNone
PDFsam BasicVery fast⭐⭐⭐⭐⭐UnlimitedLow
pdftk / qpdfUltra fast⭐⭐⭐⭐⭐UnlimitedHigh
Preview (macOS)Slow⭐⭐⭐⭐⭐LimitedNone

Which method for which case?

  • Merge 2-5 PDFs of a few MB → PDFly online, zero install
  • Merge 20+ PDFs of hundreds of MB each → PDFsam Basic
  • Automate a scripted monthly merge → pdftk or qpdf
  • macOS, offline, 2-3 PDFs quickly → Preview

Common mistakes to avoid

  1. Mixing password-protected PDFs — remove the password first if you're authorized (with the software that created the file, for example). PDFly's Unlock PDF tool is coming soon, and it will be free too.
  2. PDFs with layers — merging preserves layers, but some editors flatten them by default. Verify the result.
  3. Mixing PDF/A and regular PDF — the resulting PDF is no longer PDF/A. If PDF/A compliance matters, reconvert afterward — PDFly's PDF to PDF/A converter is coming soon (free), and Ghostscript already does it locally.
  4. Too big for email — merge then compress if sending via email.

In summary

In most cases, merging PDFs for free takes less than a minute, no sign-up, no file uploaded to a server. The best method depends on your use case, but privacy should never be a compromise.

Merge your PDFs now — free, no sign-up, no daily cap, and your files don't leave your browser.

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