A comparison of two video container formats, where MP4 offers universal compatibility and WebM provides royalty-free, web-optimized delivery.
MP4 and WebM are container formats — the packaging around compressed video and audio data. MP4 (MPEG-4 Part 14) is the most widely used video format, compatible with virtually every device and browser. WebM is an open format developed by Google, optimized for web delivery and royalty-free use. The container is not the codec — an MP4 file typically contains H.264 or H.265 video, while a WebM file typically contains VP8, VP9, or AV1 video.
A video container format is like a shipping box. It holds the compressed video stream, audio stream, subtitles, and metadata in a structured package. The container defines how these streams are organized and synchronized, but the actual compression is handled by the codec inside.
MP4 uses the ISO Base Media File Format and supports a wide range of codecs. Its universal support means any device — iPhone, Android, smart TV, desktop browser — can play an MP4 file. This compatibility made it the default format for downloaded and locally played video.
WebM was created by Google as a royalty-free alternative, primarily for web use. It pairs with the VP8/VP9/AV1 codec family. Chrome, Firefox, and Edge support WebM natively, but Safari support has been limited (Safari added WebM/VP9 support relatively recently). WebM files are typically smaller than equivalent MP4/H.264 files when using VP9, due to the better compression of newer codecs.
For streaming (as opposed to progressive download), the container format matters less because HLS and DASH fragment the video into segments regardless of the original container. Most hosting platforms accept uploads in any common format and transcode to HLS for delivery.
For teams uploading video to a hosting platform, the MP4 vs WebM choice mostly affects the upload format — the platform handles the rest. MP4 is the safer upload format because it is universally accepted. If you are building a custom video pipeline, format selection matters more for browser targeting and licensing costs. In practice, modern hosting platforms abstract this choice away entirely.
host.video accepts uploads in all common formats including MP4 and WebM, then automatically transcodes to HLS for adaptive streaming delivery. You do not need to worry about format selection — upload whatever your camera or editor produces.