Easily Compress PDF Files Online

Try an easy-to-use online solution for reducing the size of your PDF and forget about complications.
Drag & Drop the File Here
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How it works

Upload your PDF

It only takes a minute to compress your PDF file. Click the Choose file button and select the PDF from your computer. You can also drag and drop the document you’ve chosen into the box above.

Compress your Document

When you’ve finished uploading your document, click Compress and get your file size reduced in seconds. It’s simple as that. You can delete your PDF and upload a new one before you click the Compress button.

Absolutely Free

While most file compression software requires payment, AltoCompressPDF is absolutely free. There is no need to buy additional products. AltoCompressPDF will reduce the size of your PDF at no cost.

Encrypted file compression

Keeping your personal information safe is a priority for us. AltoCompressPDF uses an encrypted connection that guarantees all files uploaded are protected from unauthorized access and loss. All files are deleted from our server after they’ve been compressed.

Compatibility with major platforms

Our compression tool is compatible with all major operating systems like iOS, Linux and Windows. All you need to start using AltoCompressPDF is an internet-connected device. This means that you can shrink PDF on-the-go.

Converting files in the cloud

Even if your device's storage space is full, AltoCompressPDF will still operate. Our tool works in the cloud so you can shrink the size of your PDF whenever you need to.


File extension .pdf
Internet media type application/pdf
Description: PDF is the Portable Document Format developed by Adobe Systems. It was invented to streamline the process of sharing and viewing files independent of any software, OS or hardware. Individuals can use PDFs wherever and whenever they want on any device. PDF files can contain textual and visual data as well as links, buttons and more. PDFs can be also password protected and edited with special programs.
Technical Details: Graphics are represented in PDF very similarly to that of PostScript. PDF graphics use a device-independent Cartesian coordinate system which describes the surface of a page. The page description uses a matrix to scale, rotate, or skew graphical elements. The graphics state is a collection of graphical parameters that may be changed, saved, and restored by a page description.
Developed by ISO
Initial Release: 15 June 1993
Useful links: https://acrobat.adobe.com/us/en/acrobat/about-adobe-pdf.html

Customer Questions and Answers

I want to find an online program that can compress my image from 300kb to 150kb. BTW, the image is saved in PDF format. Waiting for some advice.
There are not many programs that provide such services. Most of them are expensive or require you to install a software to your device. However, some online platforms can still help you. Go to AltoCompress and reduce the size of any PDF file with a few clicks. Click the Choose file button, upload a document, click on Compress Now and download the newly created file to your device. You may also continue working on your document.
By Jared on May 26, 2018
What application can compress PDF files on mobile phones?
For such purposes you may need an online platform. Try AltoPDF. You can access it from any internet connected device wherever and whenever is needed. The service is free. Go to AltoCompress to reduce the size of your PDF file. Complete the process in a few clicks and save the newly created document to your device.
By Ashley on April 07, 2018
Help me to reduce the size of a PDF file. I tried some services but they actually didn't change anything.
Maybe something is wrong with the file. But still try once again on AltoCompress. Upload your file and click the Compress Now button. The size of your file should be reduced. The service is free and secure.
By Clarence on March 29, 2018
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How Do Users Rate AltoCompress?

Our service faciliates the work of over two million people converting PDF documents online every year.


How To Compress a PDF File?

How to reduce the filesize of a PDF?

To clear up more storage space, simply make your files more compact. One way to do this is by compressing files. By “packaging” a file, you make it take up less disk space. If you’re constantly adding, removing and organizing documentation stored on your computer, this may be an optimal solution for you. You are also provided with the ability to take many documents and compress them into one file, which is should be smaller than the combined size of the originals. Since PDF is one of the most popular formats for documents, you may easily find tools for transferring your PDFs.

PDFs enable users to store significantly more data. Users can then compress PDF online to 100kb. What is more, a user can post files on a web page for someone else to download and send big documents as email attachments, as most email services limit the size of each email message. It is well known, that documents may become corrupted when they are transferred over the internet in a less compressed format. Attaching documents one-by-one takes more time and effort than a bulk send. Instead just compress multiple PDFs into one and then attach them to your email message. All in all, it is easy for you to personally open reduced files from web pages or from your email application.

How to Reduce the Size of Your PDF Without Compromising Image Quality

Choose online service that offers PDF optimizer tools which exist on the cloud, so you have access to variety of operations wherever you are and whenever you need them. Even if the storage of your tablet or smartphone is minimal, AltoCompressPDF still operates. Just upload your PDF and make one click to compress PDF file size. You don’t need to download and install any additional software. No payments are required. Compress pdf files absolutely for free. See, how easy it to how to reduce PDF file size without losing quality:

  • Click the Choose button and select a document to compress into PDF or use simple drag and drop functions to put your chosen document into the box above.
  • Click Compress and see how the compression will be performed in seconds. Delete your files and upload a new one before reducing its file size.
  • Download the final result or start over again.
  • After the procedure is finished, you have the possibility to edit or sign your document electronically. Easily resize PDF image if needed.
  • Send the compressed PDF via email or fax.

Note that you are provided with encrypted file compression, so you may be sure that all your information is safe. All data is deleted from the server right after the compression is finished and can’t be accessed by any unauthorized party.

Another advantage is compatibility with all major operating systems. Compress PDF on Mac, Windows or Linux. Compress for pdf even on-the-go with your mobile device. Rather than wasting your time and efforts, use a solution, that smartly atomizes your document management for free. Try it now.