Play MKV, AVI & Other Videos Online in Your Browser
Drag a local video file into your browser and play it instantly. MKV, AVI, MP4, MOV, WebM, MPEG-TS and more. Your file never leaves your device — no upload, no account, no software to install. Optional subtitle file (.srt / .vtt) supported.
How it works
Play MKV files online
MKV (Matroska) is one of the most common containers for movies and TV shows, but no browser opens it natively. This tool lets you play MKV online by repackaging the streams into MP4 inside your browser (no quality loss), or — when the internal codec isn't supported — converting to H.264 right on your device. Drop an .mkv file and watch it instantly: nothing is uploaded. It's the fastest way to play MKV in your browser without installing VLC or another desktop player.
Play AVI files online
AVI is decades old yet still everywhere — camera footage, older downloads, recordings. Because HTML5 video ignores it, most "online players" simply fail. Here you can play AVI online directly: the file is read on your device, remuxed or transcoded to a browser-friendly format, then played back with full audio. Use it as a lightweight AVI player online whenever you don't want to install software.
Play HEVC, 4K and other formats online
HEVC/H.265 and 4K clips are common from phones, drones and cameras, but Chrome, Safari and Edge don't all decode them the same way. This player also handles VP9, AV1, WebM, MOV, MPEG-TS, FLV, 3GP, OGV and more. For a short clip the in-browser conversion is quick; for a full 4K Blu-ray library the desktop app (below) is far faster. Either way you can play HEVC online and play 4K video online without sending a single byte to a server.
Browser-native player vs. this online player
Browsers only support a handful of formats out of the box. The table shows what works natively and what this tool unlocks:
| Format | Plays in a browser natively? | With this online player |
|---|---|---|
| MP4 (H.264) | Yes | Yes |
| WebM / OGV | Yes | Yes |
| MKV | No | Yes — remux / convert |
| AVI | No | Yes — remux / convert |
| MOV (some codecs) | Partial | Yes |
| HEVC / H.265 | Partial (Safari only) | Yes |
| MPEG-TS / FLV / 3GP | No | Yes |
| External SRT / VTT subtitles | VTT only | SRT + VTT |
Frequently asked questions
Which formats and codecs are supported?
Containers: MKV, AVI, MP4, M4V, MOV, WebM, MPEG-TS/M2TS, FLV, OGV, 3GP and more. Codecs supported by your browser play without conversion; anything else is repackaged or converted to H.264/AAC automatically. Very large or 4K HEVC files can take several minutes to convert.
Is my video uploaded to a server?
No. The player and the FFmpeg WebAssembly engine run entirely on your device. Your file is read locally and never transmitted. You can even disconnect from the internet after the page has loaded.
Why does my browser not open MKV or AVI directly?
HTML5 video only supports a few containers such as MP4 and WebM. MKV, AVI and TS use different containers, so this tool repackages (remux) or converts the file in your browser to a format the HTML5 player can open.
Can I play AVI files online without installing software?
Yes. AVI is not supported by HTML5 video, so most websites cannot open it. This tool reads the AVI on your device, remuxes or transcodes it to a browser-friendly MP4, and plays it back with audio — no VLC or other desktop player required.
Can I play HEVC or 4K video online?
Yes. HEVC/H.265 and 4K clips are handled in your browser. Because not every browser hardware-decodes HEVC (notably Chrome), the file may be re-encoded to H.264 on your CPU — fast for short clips, slower for long 4K footage. For a full 4K Blu-ray library, the desktop Total Video Player Pro for Mac is much quicker.
Can I add subtitles when playing a video online?
Yes. After the video loads, choose an external .srt or .vtt subtitle file and it is attached to the player automatically. The subtitle file is also processed locally and never uploaded.
Do I lose quality?
If your file's codec is already browser-friendly (e.g. H.264 inside an MKV), it is only repackaged — zero quality loss. If re-encoding is required, H.264 CRF 26 is used, visually near-lossless for typical content.
HEVC/4K videos are slow — what should I use instead?
Browsers cannot hardware-decode every codec (notably HEVC on Chrome), so conversion runs on the CPU. For fast, hardware-accelerated playback of HEVC, 4K, Blu-ray and MKV with styled subtitles on your Mac, use Total Video Player Pro for Mac.
Supported formats in detail
The player handles three groups of files. First, containers your browser already understands — MP4, WebM and OGV — which open instantly with no processing at all. Second, containers the browser will not open but whose internal codec it can decode, such as most MKV and MPEG-TS files; these are repackaged into MP4 without re-encoding, so there is no quality loss and the wait is short. Third, files whose codec the browser cannot decode, such as HEVC/H.265 in Chrome, legacy DivX or Xvid inside an AVI, or some 4K camera files; these are re-encoded to H.264 with AAC audio at CRF 26 and capped at 1080p.
Video codecs handled include H.264, HEVC, VP8, VP9, AV1, MPEG-2 and MPEG-4 Part 2. Audio codecs include AAC, MP3, AC3, Opus, Vorbis and FLAC. External subtitles can be attached as .srt or .vtt — the file is converted to WebVTT inside your browser and attached as a text track.
Troubleshooting: when a video will not play
Nothing happens when I drop the file
Check the file extension first — an unusual or missing extension can prevent detection. If the file is larger than about 1.5 GB you will be asked to confirm, because browsers allocate memory per tab and very large files can exhaust it. If conversion starts and then fails, the file may be damaged or use a codec the engine cannot read.
Video plays but there is no sound
Some containers store audio in a format the browser will not decode, most commonly AC3 or DTS inside an MKV or AVI. The conversion step re-encodes audio to AAC, which browsers handle natively, so allowing it to finish usually restores the sound.
Playback stutters or drops frames
A re-encoded 4K file is demanding to decode inside a browser tab. Try a smaller file, close other tabs, or use a desktop player with hardware acceleration.
Subtitles do not appear
Choose the subtitle file only after the video has loaded, and make sure it is a plain .srt or .vtt. Some players also keep subtitles hidden until you enable the text track in the player's own control menu.
When to use a desktop player instead
Browser playback is ideal for a quick check: you want to preview a clip, confirm a file is not corrupt, or watch something once without installing anything. It is not the right tool for a large library. Every conversion runs on your CPU inside a single browser tab, a two-hour 4K HEVC film can take a long time to re-encode, and browser tabs are limited to roughly 4 GB of memory.
If you regularly watch MKV, AVI, Blu-ray or 4K files on a Mac, Total Video Player Pro decodes them with hardware acceleration, loads subtitles automatically, handles multiple audio tracks and remembers where you stopped — with no conversion step and no waiting. That is exactly what this free tool is here to point you towards.
Need this for real work on your Mac?
Total Video Player Pro for Mac plays MKV, AVI, Blu-ray and 4K HEVC at full speed with automatic subtitles, multi-audio tracks, playlists and styling — no conversion, no waiting, works offline.