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

Explore Other Ways to Do More with Your Documents

Upload a PDF

Compress any scanned or image-based PDF in seconds. Drag and drop your document into the box or import it from an online location.

Compress Your Document

Wait for the upload to finish. Click the ‘Compress Now!’ button to process your file immediately or the Trash button to start over.

Use it for Free

Forget about paid and downloadable applications! AltoCompressPDF is totally free and allows you to have an unlimited number of uploads.

Encrypted File Processing

With our app you are always in control of your data safety. Each document you upload is processed via an encrypted connection.

Compatible with Any Device

AltoComressPDF is a web-based app. Run it on any of your devices regardless of its type. It works with desktop, mobile, or OS.

Compress Documents in the Cloud

Processing files in the cloud enables you to operate faster. Compress PDFs on any Internet-connected device and forget about complications.


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.

How To Compress a PDF File?

How to reduce the file size 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 it 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.


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.

Did you know?

PDF documents can be compressed

To compress Word or Excel documents down to a more manageable size, just convert them to PDF. This way, you won’t lose any quality characteristics. Another benefit is the editing option. You can edit a PDF document as well as enhance it with visual and graphical elements.