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(s) Here

Safe and secure

Quick and easy

No email



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

How-to guide

How to reduce the size of a PDF document online

  1. In order to compress a PDF, open AltoCompressPDF.com in your web browser.
  2. Click Choose File to add a document from your hard drive.
  3. Click a cloud storage service icon to add a PDF stored online.
  4. Wait for your upload to finish, then click Compress Now!
  5. Click the Trash icon in case you’ve uploaded the wrong document.
  6. Wait while your new PDF is being generated, then choose what you want to do with it.
  7. Click Work on your PDF to redact it or share it with other users.
  8. Click Download Now to download the resulting PDF back to your device.

The Ultimate Features Comparison Chart

Due to the high level of competition on the web, choosing the best application can be challenging β€” especially if you don’t accurately compare it with the alternative options. Our benchmark table will help you easily pinpoint your preferred tool to Compress PDF. Get to know the forward features of AltoCompress.

Split PDF βœ” βœ” βœ”
Merge PDF βœ” βœ” βœ”
Combine & Reorder βœ” ❌ ❌
Extract Pages βœ” ❌ ❌
Compress PDF βœ” βœ” ❌
Rotate PDF βœ” βœ” ❌
No software downloads βœ” βœ” ❌
Cloud storage Unlimited No info No info
Price Free Free 7-Day Trial paid Free 7-Day Trial paid
Encryption and security βœ” βœ” βœ”
Support 24/7/365 No info βœ”
No ads βœ” βœ” βœ”

Customer Reviews β€” Trusted by great people



Excellent solution! If the size of your PDF document is too big, reduce it with just a few clicks. It solves the memory shortage problem. Plus it’s so quick!



What I like best about the AltoPDF tool is that no registration is required. Creating an account is one of those things that makes me wanna leave the website.



That’s awesome! I can compress my PDF files from any device, even when I’m in a taxi or on a buss, or walking on the street. It take up memory cause no installations are needed.

Your opinion matters!

If your experience was picture-perfect, please take a moment to tell us so.

How To Compress a PDF File

Using this service everyone can decrease the size of the PDF file in several simple steps. Just open the website and compress the document from any device.

How to Compress PDF Files Online

This website was created so you could compress files quickly and easily. Its ease of use and compression speed makes it one of the top solutions for decreasing file formats online. The best thing is the quality of images and text included in the document will always remain the same. The solution doesn’t take up any memory on your device and it never needs to access your personal information. This website is cross-platform and is available from any internet-connected device. 

Here’s how you can easily compress the file size online:

  1. Open the web-based service. Browse for a file in your device’s internal storage or in the cloud. Import it to AltoCompressPDF.
  2. Once the template is available, compress it.
  3. Save the document with the newly-deceased file size to your storage.
  4. Repeat this operation for as many files as you need.

Usage of an online platform saves you time, money and space. And the location of all of the tools in the cloud eliminates the need for installation. We offer the highest security measures and the possibility to compress the size of as many documents as you need. The platform has a lot of additional online options available for free use. You can reduce files without any payments, registrations or trial periods. For those who want to use this tool on the go, a lite mobile app is available.

BackgroundHow to Compress PDF Files Online

How to Compress PDF With Chrome Extension

Google Chrome is one of the most frequently used browsers. It’s compatible with numerous extensions and online-based services for compressing PDF files. It’s preferable to install the browser extension. Those who work with documents often should add Alto Compress extension to your browser. 

With it any large-sized PDF will be easily decreased without breaking file formatting or losing quality. The service perfectly integrates in Chrome. 

Here are step-by-step instructions on how to compress PDF files with Alto PDF:

  1. First, visit the extension store and find a solution via inserting its name in the search field.
  2. Open the extension and add it to Chrome. It will install and appear at the upper left corner.
  3. Click at the Alto Compress icon and the pop-up window will appear. 
  4. Select the template for compression from your computer or cloud Drive. 
  5. Wait until the operation finishes and the final file with decreased size will be available. Click at the compressing option and the template’s size will be decreased.
  6. Download the final sample version to the internal or cloud storage. 

Usage of Google Chrome Alto Extension on any device, no matter whether you install it to the mobile or desktop, gives you an advantage. All internet-based services have numerous features but do not take up the memory of the user’s device. Thanks to that, with this browser everyone gets the opportunity to decrease the size of a large PDF file free of charge. Additionally, the image quality will never be damaged.

BackgroundHow to Compress PDF With Chrome Extension

How to Compress PDF Files in Windows

Windows users often use PDFs. In fact, it is one of the most popular formats out there. So undoubtedly, it’s vital to understand how to make basic operations with PDFs. Some users prefer installing additional software to their computers or they also can process documents via online services. You can choose the one you prefer —  a free or paid solution, as well as an application or online website with a cloud-based toolkit. 

Let’s take a look at how one can complete this operation in Windows:

  1. Open the solution for compression. 
  2. Browse for a file in your device’s internal storage or cloud.
  3. Import the file and once it’s ready, complete the conversion.
  4. Save the final template with the decreased size to your preferred storage.

Unfortunately, Windows does not have pre-installed solutions for editing, converting or reducing the size of PDF samples. There are a wide variety of applications that combine multiple features in one. Still, there are also apps that only concentrate on specialized features. For example, it can be the conversion, the signing of a document or extracting its pages. Most of them are free and available from any Internet-connected device via a browser. Those apps are good for those who have no time for installation and making payments. 

BackgroundHow to Compress PDF Files in Windows

How to Compress PDF Files With Preview on Mac

The popularity of PDFs among Mac users is constantly growing. That is why Mac OS developers added some features for processing those files without additional software. Viewing content in PDF is quite simple when you use the default “Pages” application. Also, it’s possible to decrease a PDF’s size on Mac. And compressing the size is simple for Mac users as well. Let’s take a closer look at how this feature works. Here is the step-by-step instruction:

  1. Open the file for a preview. 
  2. Select the File option and click on Export.
  3. A new window will appear. Click on Quartz Filter and select the Reduce File Size option from the list to compress a file.
  4. Specify the location of the future template and save it. 

Mac default applications can effectively reduce the size of PDFs without losing the quality of images. This feature is very helpful for those who need to work with these files on a regular basis. For example, for designers or marketing executives, PDF templates with pictures, spreadsheets, countings, and textual data are primarily used. As a result, it becomes easier to process files and share them between different users.

BackgroundHow to Compress PDF Files With Preview on Mac

How to Compress PDF Files With Adobe Acrobat Reader

Since Adobe originally created PDF documents, Acrobat reader remains one of the most popular solutions for working with them. Acrobat Reader is an application created to make multiple operations with Portable Document Files. It has a desktop and mobile version. If you want to install the mobile app, be ready for additional purchases and remember that the trial version is free. No matter what type of app you are using, registration and synchronization with your Google or Facebook account will be required. 

Compressing files in Adobe Acrobat works like this:

  1. Install the app on your device and complete registration.
  2. Then open the PDF document in Acrobat.
  3. Select the Tools option. Choose Optimize PDF.
  4. Click on Reduce File, which is available in the toolbar above the document. 
  5. Go to Advanced Optimization for making custom settings.
  6. Press OK to save changes. Add the location of the future file and save it.

Adobe Apps work through a license validation. That is why its usage is impossible without registration. It starts with you entering in your email address or signing in through a social network. Next, a message with a code goes to your email address. The code is used to log in. It will then be necessary to use a password. This is good for those who work with PDFs often and have a bad internet connection. However, it takes longer than online free sites because the user needs to install it and undergo the registration process.

BackgroundHow to Compress PDF Files With Adobe Acrobat Reader

How to Compress PDF on the Phone

It’s not necessary to use expensive software to reduce the size of your PDFs. Compress any PDF on a smartphone for free! This opportunity is possible with Alto. Complete some uncomplicated actions to start compressing your PDFs today. 

  1. Go to AltoCompressPDF.com and click Choose File at the top of the page. 
  2. Upload the file from your device or cloud storage. 
  3. Tap Compress Now!.
  4. When your file is compressed, decide what you will do next: open it with pdfFiller to edit and sign it or save it with the Download Now button and finish. 

After compressing your PDF it’ll become smaller and will take up less space in your phone’s memory. Consider compressing all of your large Portable Document Format files. This way, you’ll optimize your storage space and increase your overall effectiveness. 

This service is available without having to pay or sign up. Get the compressed document in less than a minute right from our website.

For those who work with PDFs often, check out other useful services on altopdf.com. 

BackgroundHow to Compress PDF on the Phone

How to Compress PDF on iPhone

Reducing the size of your documents is a good idea and a necessity for people who store their PDFs on iOS devices. Compress PDFs on your iPhone to optimize your storage and avoid paying for additional cloud drives. With the Alto platform and it’s range of services, saving storage on your iOS devices is easy. See how below: 

  1. Launch Safari or any other browser and open altocompresspdf.com. 
  2. Hit Choose File and add a document from your device or cloud service.
  3. Make sure that you have uploaded the correct sample. Click the Trash button to delete it and upload another one or Compress Now! to start the process. 
  4. Tap Download Now and receive your compressed file. 
  5. Choose one of the options above the Download button if you’d like to test out pdfFiller’s powerful editing tool. 

Compress any PDF on an iPhone or iPad and optimize your storage. Individual files are typically small and don’t affect your storage so much, however the problem arises when you have many small files. Together they take up space. 

In addition to saving space, smaller files can save data too. Sending smaller documents is faster and uses up less of your network.  

Don’t be scared about compressing your files. With AltoPDF compressed PDFs always retain their quality. Use them with other PDF editors like Adobe Reader and pdfFiller. 

BackgroundHow to Compress PDF on iPhone

How to Compress PDF on Android

You can easily compress PDFs on an Android without installing any new applications. The Alto tool is available directly from your browser. Open your preferred browser to begin compressing: 

  1. Go to altocompresspdf.com. 
  2. Click the orange button and select the document you want compressed. 
  3. Tap Compress Now! After you’ve uploaded your file.
  4. Wait while your file processes. Click Download Now to finish or select Start over again to compress more files. 
  5. Click Share, Save Document As, Edit Documents or Sign & Secure to use these features in pdfFiller’s editor. 

After you finish compressing your file, feel free to continue onto pdfFiller and check out all the cool features it has for managing documents. In pdfFiller you have access to adding fillable fields, highlighting, and signing documents. The best part is that you can use pdfFiller without ever leaving your browser. 

By optimizing the documents you save to your device, you optimize its storage. Your samples will take up less memory and network space, thus leading to faster file sharing. 

Any document can be compressed in less than a minute. Consider using this service more often and don't forget to save altocompresspdf.com to your Favorites tab. 

BackgroundHow to Compress PDF on Android


There are several ways to compress pdf docs. The most popular are offline software and online tools. While software requires time and costs to install, online platforms like AltoCompressPDF help you avoid such problems and is very convenient, as it is available on the go from any device. Take three steps: upload the document, click the orange button and download the downsized one to your computer.