Is PDFWix really free?

Yes. Every tool on PDFWix is free to use with no daily task limits and no watermarks added to your files. We may charge for high-volume API usage in the future, but the web tools stay free.

Do I need to create an account?

No. Every tool works without signing in. An optional free account just keeps a history of your conversions (filename and tool only — never your files) and unlocks the developer API.

Do you store my files?

Most tools (merge, split, rotate, watermark, edit, JPG↔PDF, etc.) run entirely in your browser — your file never reaches our server. The two tools that need server processing (Protect PDF, Unlock PDF) process your file in memory and never write it to disk.

What's the maximum file size?

Browser-side tools handle PDFs as large as your device's RAM allows — roughly 100 MB on a typical laptop, less on phones. Server-side tools (Protect, Unlock) accept files up to about 25 MB per request.

Do you add watermarks to my PDFs?

No. PDFWix never adds a watermark, footer, or branding to anything you create. The output is exactly what you asked for, nothing else.

Does PDFWix work on iPhone, Android, and Chromebook?

Yes. PDFWix is a web app — it runs in any modern browser on any device. There's nothing to install. You can also add it to your home screen on iOS or Android for a one-tap launcher.

How is PDFWix different from iLovePDF or Smallpdf?

Three differences: most PDFWix tools run inside your browser (your file never leaves the device), there are no daily task caps on the free tier, and we never put a watermark on your output. As of June 2026, PDFWix has 24 live tools across merge, split, compress, sign, redact, and convert with no daily task limit and no file upload for 22 of them.

Is PDFWix safe for confidential documents?

For browser-side tools, yes — your file is processed locally and never transmitted anywhere. For the two server-side tools (Protect, Unlock), files travel over HTTPS and are processed in memory only. We never read, scan, or train AI on your documents.

Can I use PDFWix for commercial work?

Yes. There's no license restriction on what you produce with PDFWix. Use it for client work, internal documents, contracts, anything. The developer API is available if you need to embed PDF processing into your own product.

What happens if a tool fails or I find a bug?

Email support@pdfwix.com or use the "Report an issue" link in the footer. We read every message and ship fixes quickly.

Which PDF tools run entirely in my browser?

Twenty-two of the 24 PDFWix tools run entirely in your browser using WebAssembly — your file never leaves your device. The two exceptions are Protect PDF and Unlock PDF, which require server processing but handle your file in memory only and never write it to disk.

Is there a file size limit?

Browser-based tools handle files up to the available RAM on your device — typically 500MB or more on modern computers. Server-side tools (Protect, Unlock) currently support files up to 100MB.

Does PDFWix work on iPhone and Android?

Yes. All 24 PDFWix tools are fully optimised for mobile browsers. No app install required — open pdfwix.com in Safari on iPhone or Chrome on Android and every tool works exactly the same as on desktop.

Home / Guides / Merge and Compress PDF

merge

Should You Merge PDFs First or Compress First?

Merge first or compress first? The order significantly changes your final file size. Explains why and gives a free browser-based workflow. No signup needed.

5 min readUpdated 2 days agoNo upload

PPDFWix Team· Reviewed for accuracy

Files never uploaded Runs in your browser No signup No watermark

Merge PDF Free

Live · in browser

Merge first, then compress. Merging first lets the compression engine analyse all pages together and apply consistent optimisation across the whole document. Compressing before merging can actually increase final file size because each PDF is compressed independently and then re-combined, adding per-file overhead.

Why the order of merging and compressing matters

When you merge two PDFs and then compress the result, the compression engine (in PDFWix, this is Ghostscript via WebAssembly) analyses the entire merged document as a single unit. It can deduplicate shared resources — fonts used in both documents appear only once, identical image resources are deduplicated, and the compression dictionary covers the entire document. This produces a smaller final file than compressing each PDF individually before merging.

If you compress first then merge: each PDF is compressed independently and packaged with its own resource dictionaries. When merged, these separate resource packages are combined, sometimes resulting in a file that is larger than either compressed file alone. The merge adds structural overhead on top of two already-compressed documents.

The recommended workflow: Merge → Compress

Open PDFWix Merge PDF.
Upload all the PDF files you need to combine. Reorder them if needed by dragging.
Click Merge and download the combined PDF.
Open PDFWix Compress PDF.
Upload the merged PDF. Choose Recommended or High compression.
Download the final compressed merged PDF.

When compressing before merging makes sense

There is one scenario where compressing before merging is the right approach: when one source PDF is very large (50MB+) and you need to reduce it before merging because your browser cannot handle the combined file size in one operation. In this case, compress the oversized file first to reduce it to a manageable size, then merge. This is an edge case — for most everyday merging tasks, merge first then compress.

For more on merging PDFs with mixed page sizes, see our guide to merging PDFs with different page sizes.

Use the free PDFWix tool:

Frequently asked questions

Does merging PDFs increase file size?

Yes, slightly. Merging combines the file structures of multiple PDFs, and if each PDF has separate embedded fonts and resources, the merged file size can be larger than the sum of the parts. Compressing after merging eliminates this overhead by deduplicating shared resources across the combined document.

How much can I reduce a merged PDF by compressing it?

A merged PDF containing scanned documents typically compresses 60–85%. A merged PDF containing digital text documents compresses 15–30%. The compression ratio depends on the image content of the source PDFs, not on the number of files merged.

Can I merge and compress in one step?

PDFWix currently handles merge and compress as two separate operations in the browser. Merge first, download the merged PDF, then open PDFWix Compress PDF and compress. Total time is typically under 30 seconds for most documents.