What is an M3U8 file?
M3U8 is commonly used as the playlist format for HTTP Live Streaming (HLS). A playlist can point to multiple quality levels or directly to media segments. Modern browsers may play HLS natively or through a JavaScript player using Media Source Extensions.
What this HLS tester checks
The tool listens to player events and surfaces details that are useful when troubleshooting: manifest parsing, quality levels, dimensions, bandwidth metadata, codecs when reported, live/VOD state and fatal or non-fatal hls.js errors.
Why an M3U8 URL may not play
CORS
If the remote server does not allow your website origin to request the manifest or segments, a browser-based player cannot override that server policy.
403 Forbidden or expired token
Signed URLs often expire. Some servers also require cookies, request headers, IP allowlists or an approved referrer.
404 or missing segments
The master manifest may exist while one child playlist or media segment has already been removed.
Mixed content
An HTTPS page is normally blocked from loading an insecure HTTP media resource. Use an HTTPS stream whenever the tool itself is served over HTTPS.
Legal use
This page is designed for testing streams you own or are authorized to access. It does not provide a downloader or a method to defeat access controls.
Related guides
What is M3U8? · M3U8 not playing: troubleshooting checklist · How to test an HLS URL