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Top 3 Online PDF Compressor 2019

By Carrie Murray, Tuesday, May 21, 2019

The best way to reduce PDF file size is by using an online PDF compressor. It is quick and can compress a PDF file to 100KB, 200KB or below without downloading any software on your computer.

There are so many online PDF compression tools that you may find it hard to select the best one. After testing more than 20 PDF compressors online, we have selected the Top 3. What makes these 3 PDF compressors stand out is that they can significantly reduce PDF file size without losing quality, and most importantly, they are totally safe for PDF compression.

PDF Files

Is PDF Compressor Online Safe?

One of the biggest concerns about compressing PDF files online is that your private information in the PDF file may be accessed by others. In fact, most online PDF compressors provided by legitimate websites are safe to use. They won't store your PDF files or send them to other platforms.

However, you should be cautious about online PDF compressors that are crammed with ads, which may contain malicious links that are not safe for your computer.

FonePaw Free PDF Compressor

FonePaw Online PDF Compressor is completely free to use. It has no limit on how many PDF files or the file size you can compress and there is no need to sign up or log in for the compression online.

The compressor can reduce PDF file size by up to 85% with losing quality. It makes PDF files smaller for uploading to the web or sending via emails while keeping the files in good quality for printing or zooming.

FonePaw Free PDF Compressor

To reduce PDF files size with this online compressor, just open the PDF compressor online, click Add PDF File to select a file or drag and drop PDF file in the compressor. The PDF will be uploaded and compressed automatically. 

Compressing PDF

Click Download File to get the PDF in a smaller size. PDF compression can be completed in just a few seconds.

Download Compressed PDF


Highest compression ratio without sacrificing quality; Totally free to use with no limit on the compression number or size; No need to sign up or download anything; Compatible with all browsers on Windows, Mac, iOS or Android devices; Safe for your PDF files.


Can't convert, merge, split PDFs.

Smallpdf Compress PDF

Smallpdf is a complete PDF compressor, converter, and editor online. It can reduce PDF files to 144 DPI, which is perfect for a web page. The maximum file size for uploading PDF to this online compressor is 5GB. It also offers desktop PDF compressor software.

Smallpdf Compress PDF

It works similarly to other online PDF compressors like FonePaw Free PDF Compressor. Just upload a PDF file to the compressor and it will automatically reduce the file size and allow you to download the compressed file. In our tests, Smallpdf achieves a lower compression ratio than FonePaw PDF compressor when optimizing the same PDF file.

Smallpdf Compression Result

And you should know that Smallpdf online PDF compressor is not totally free to use. On one computer, you can compress no more than 2 PDF files within an hour. To remove the limit, you need to purchase the pro version, which is $6 per month and $48 per year.


  • Comprehensive. Not only it can compress PDF online, but it can also convert files to PDF, edit PDFs;

  • Offer PDF compressor software to compress PDF offline;

  • Compress PDF files from Google Drive or Dropbox.


  • Not free to use;

  • Limit on the number of PDF files you can compress;

  • Lower compression ratio for PDF files.

iLovePDF Online PDF Compressor

Similar to Smallpdf, iLovePDF is a multi-purpose online tool for PDF compression and conversion. The tool is not totally free to use for reducing PDF file size. When using the free version, the PDF files you can upload should no larger than 200MB and no more than 2 files can be compressed at each task. To bypass these limits, you need to register and upgrade to the premium version, which is $6 per month.

After uploading PDF files to the compressor, it offers 3 choices: extreme compression, recommended compression, and less compression. By extreme compression, the PDF file can be reduced to the minimum size, which will cause damage in quality. In the other hand, the less compression can maintain a good quality but only achieve an extremely low compression ratio (less than 10%). Therefore, select the recommended compression to get a better result. 


After compression, the compressor will download the compressed PDF file automatically, which is a little inconvenient when you are not satisfied with the compression result and want to cancel the download.


  • Offer PDF compressor software for PC and compressor app for Android & iOS;

  • Upload and save PDF files from/to Google Drive, Dropbox;

  • Compress PDF files in 3 modes.


  • Automatically download the compressed files;

  • The free version is offered with ads.


If you only need to compress PDF files to smaller file size, use FonePaw Free PDF Compressor which doesn't cost you a penny. Also, FonePaw offers a free compressor for PNG, JPG files as well. If you also need to convert PDF files, try Smallpdf or iLovePDF.

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