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Top 3 Free Online Video Compressors [Review & How to Guide]

How to Compress/Reduce Video Free Online? Find Out Best Free Online Video Compressor!

Changes are inevitably acted on raw videos. Stock video footage coming from HD/4K camcorders produces troubles when either to upload for sharing on YouTube, Facebook, Instagram…sending to your friends via email, or to transfer to portable devices for movable playback because of undesired giant size. We have to compress original video making it fit network transportation or better play on more screens.

Online video compressor is recognized as the most convenient solution to compress and reduce video file size. It is free, effective and easy to use. But how to judge whether a video compression site is serviceable or not? Here, we give a chart of top 3 free online video compressors.

Download the Best Free Video Compressor for PC/Mac to Shrink Video for SNS/Email/Devices…

WinX Video Converter brings a great experience of video compression without ads, malware, file size limit, and even no network required.
• Compress 8K/4K videos to 1080P, 720P, 480P, 360P for better playback on mobiles/laptops with lower resolution displays.
• Cut unwanted part or crop black bars to reduce video file size for online sharing, YouTube uploading, email delivering and more.
• Convert HD videos (MKV, MTS, MOD) to MP4, HEVC, AVI, WMV, MOV, FLV, 3GP etc, with smaller size while keeping possible highest quality.

Part 1: What You Should Know About Video Compression

Video compression is not a hard task by making use of online video compressor. But learning of basic knowledge of video compression is a necessity to help us know how to compress a video to precisely meet our requirement.

Factors Affecting Video File Size

• Bitrate
Bitrate is the crucial factor affecting video file size, which tells how many bits are transmitted to form pictures and audio streams per second. It determines data amount of a video. Higher bitrate produces bigger video file size and requires more spaces. Even in different resolutions, video file size has no change at the same bitrate. Please note that matched bit rate and resolution can deliver better video quality.

• Runtime
Generally speaking, video file size = bitrate * runtime. If bitrate is invariable, the longer the video runs, the bigger size it will be.

• Codec
Codec is used to encode or decode a video. Some codecs with high compression ratio can provide good video quality at a lower bitrate (for example H.265/H.264). Some codecs are specially designed for web, mobile etc, which also output a video with small size (for example VP9/8). Therefore, we can also compress video file size by converting original video format to another one encoded with those special codecs.

We test 3 videos with the same duration (00:30) but encoded with different codecs and at different bitrate. The results obviously show how important bitrate and codec for video file size.


File Size




Frame Rate


29.5 MB






17.2 MB






14.8 MB





Part 2: 2021 top 3 Free Online Video Compressors [Reviews & How to Guide]

Clipchamp – No.1 Online Video Compressor

Clipchamp is a rising star which aims to offer the easiest solution to convert/compress videos and record webcam videos free. It supports a large range of input video formats like MP4, AVI, WMV, FLV, MKV and more. Instead of specific output video formats, it gives 4 profiles, Web, Windows, Mobile and Animation (GIF), which include the optimal video formats which deliver smaller size of original video but keep good quality. Besides, users are allowed to set video resolution, quality and trim videos to shorter for reducing video file size. After the compression process is done, user can directly upload to YouTube/Facebook and share online or save to hard drive.

• It is easy, free and fast. No ads on page.
• It provides customize settings and editing tools for further video compression.
• Video formats are limited.
• User must log in with an account to access to video compression.

How to Compress Video Free Online via Clipchamp

Top Free Online Video Compressor - Clipchamp
Top Free Online Video Compressor - Clipchamp

1. Open and hit Tools -> Compress on its home page.
2. Continue with Google, Facebook account or register one.
3. Upload one or more video to this online video compressor.
4. Select one profile (Web, Windows, Mobile, or Animation) and set/edit video according to your needs.
5. Click Start to compress video. Once it is completed, you can select UPLOAD & SHARE online or SAVE to computer.

Convert.Files – No.2 Online Video Compressor

Convert.Files is a web-based application to convert and compress videos without registration. Like Clipchamp, it is available to input and output almost all mainstream video formats like MPEG4, H.264, AVI, WMV, MOV, MKV, FLV, 3GP. It also enables to extract audio tracks from video files. Apart from compressing local video, it enables users to download from online and shrink it to other formats for mobile playback, email delivery or other purposes. Not only working as an online HEVC video converter and compressor, it is an all-in-one file converter which can perform conversion between audios, e-books, images, documents and more.

• No account is needed! Free and easy-to-use!
• Abundant video formats allow us to select the best format to compress video to.
• So many ads adhere to the page. Some confusing one may mislead us.
• The resulting video file may be corrupted and cannot be opened.

How to Compress Video Online via Convert.Files

Top Free Online Video Compression Software - Convert.Files
Top Free Online Video Compression Software - Convert.Files

1. Open and click Browse to choose a local video file you want to compress on its home page.
2. Input format will be auto checked. Now, select output format. If you want to compress video for email or web, FLV and 3GP are recommended.
3. Click convert. The video will be uploaded firstly and converted next.
4. After all is done, a download page with a download link will be given to you. Select "Save Link As" to download the compressed video.

Zamzar – No.3 Online Video Compressor

Zamzar integrates with hundreds of converters to support various conversions, including video, audio, image, e-book, document etc. It is definitely an online expert on video compression. It embeds much more video formats (codes) than other two free online video compressors, not only containing general video formats, H.264, MP4, AVI, WMV, MOV, FLV, 3GP, WebM etc, but devices profiles iPhone, iPad and iPod. It also offers an URL converter helping users convert and compress online videos to other video/music formats.

• It is easy-to-use.
• It supports most output video/audio formats and additionally provides devices profiles.
• Ads on page are quite annoyed.
• It is only free for compressing videos smaller than 50MB.
• It requires email address for compressed video download. And, you cannot receive email immediately but wait for several hours even more.
• It delivers slowest conversion speed among top 3 free online video compression software.

How to Compress Video Online via Zamzar

Top Free Online Video Compressor - Zamzar
Top Free Online Video Compressor - Zamzar

1. Open Click Choose Files… button in Step 1 to upload video from hard drive.
2. Select an ideal video format which can make video to be greatly compressed from "Convert files to:" drop-down list in Step 2.
3. Input your email address into text box in Step 3.
4. Click Convert button in Step 4 to start compressing videos online free.

Part 3: Possible Problems When Compressing Video to Smaller Size Online

Merits of online video compressor are apparent. Firstly, users can complete video compression online without downloads and installation. To some extent, this kind of video compression can save us much time and space on computer. Secondly, all online video compressors have straightforward UI and even on-page guide so that every user can quickly get how to use. On the other hand, disadvantages cannot be ignored.

1. Online video compressor relies on networking and bandwidth. The compression speed will be badly influenced by poor network condition. Certainly, it is completely useless if there is no network.
2. Most online video compressor sites put lots of advertisements on pages. Some ads are safe but suck while some ads are very dangerous with virus affected.
3. The free services always require something, like registration, email address, limited file size (usually <500MB), making it impossible to compress 4K or large-sized HD videos.
4. Resulting file may be broken or unaccessible for failed compression but we cannot be aware of that until an output is given.
5. Online video compressor only compresses videos only through conversion or small editing, which cannot achieve a best compression.

Part 4: Best Desktop Software to Compress Videos - Alternative to Online Video Compressor

Comparing to online video compressors, desktop video compression software has more powerful functions and stable performance beyond doubt. WinX Video Converter is the best free video compressor we pick out from the market through several times of tests.

• With the support of hundreds of codecs, it can convert and compress 8K/4K/HD videos to MP4, AVI, WMV, MOV, FLV, 3GP, WebM etc, for YouTube/Facebook uploading, online sharing, email sending, devices playback and more.
• Parameters, like bitrate, resolution, frame rate, aspect ratio, can be adjusted for reducing file size to smaller.
• Unwanted parts can be cut/cropped off from video to shorten video length.
• It is as easy-to-use as online video compressor but much safer without malicious stuff bundled. It requires no networking and runs much faster by making use of GPU hardware acceleration.

>> Learn How to Compress and Reduce File Size with WinX Video Converter

External Sources from Wiki:

Video Compression uses modern coding techniques to reduce redundancy in video data. Most video compression algorithms and codecs combine spatial image compression and temporal motion compensation. Video compression is a practical implementation of source coding in information theory. In practice, most video codecs also use audio compression techniques in parallel to compress the separate, but combined data streams as one package....


author - Brent Archer

Brent Archer twitter icon

Brent Archer is an experienced editor who loves all things related to social. He has spent more than a decade writing instructional contents related to social media, streaming services and video related topics all over the internet for Digiarty. Outside the social, he is addicted to Google I/O, Apple WWDC and other tech news to keep him informed.

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