Convert Video Online — Free, No Upload

How it works

Drop your file
Any common video or audio format, any size. Nothing is uploaded.
Pick your format
Video out: MP4, WebM, MKV, MOV, GIF, AVI, WMV. Audio out: MP3, WAV, M4A, M4R, OGG, AAC, FLAC, WMA, AIFF.
Download
Instant for compatible files, hardware-fast for the rest — with a lossless badge when nothing was re-encoded.

Remux or re-encode: why some conversions finish in a second

A video file is a container (MP4, MKV, MOV, WebM, TS) holding streams in codecs (H.264, HEVC, VP9, AAC, Opus). Most conversions people need are container problems — the player refuses the box, not the picture. When a stream’s codec already fits the target container, ConvertUno copies its packets straight across without decoding a frame. That is a remux: bit-identical output, finished in about the time it takes to read the file. The engine’s rules:

Target	Video copied as-is	Audio copied as-is	Anything else is encoded to
MP4, MOV, TS	H.264	AAC	H.264 + AAC
MKV	H.264, HEVC, VP8, VP9, AV1	AAC, Opus, MP3, Vorbis, FLAC	H.264 + AAC
WebM	VP8, VP9, AV1	Opus, Vorbis	VP9 + Opus

In practice MKV to MP4, MOV to MP4 (H.264 iPhone recordings) and TS to MP4 or MTS (AVCHD camcorders) remux for the common case, and MP4 to MKV, MOV, TS or M4V remuxes whenever the MP4 holds H.264 + AAC — most of them. WebM to MP4 can never remux, because VP8/VP9 is not an MP4 codec, and neither can an HEVC iPhone clip; those are decoded and re-encoded on your graphics hardware. The re-encode targets the source’s own data rate plus 15% headroom (clamped to 0.25–8 Mbps), with extra bits (×1.55, or ×1.9 two generations down) when translating HEVC or AV1 into the less efficient H.264.

The result panel shows a lossless badge only when every stream that exists in the source was copied. Remuxing never shrinks anything — a smaller file is the compressor’s job.

Getting audio out of a video

Choose an audio format and the video track is discarded on purpose. The same copy rule applies: a codec that already matches the target is lifted out untouched — an AAC track becomes an M4A, a WebM’s Opus becomes an OGG, and a video already carrying MP3 audio gives you that exact MP3 back. Everything else is decoded and re-encoded: MP4 to MP3 (or any video to MP3) writes 320 kbps MP3 on every route from sources sampled at 32 kHz or above (lower-rate sources keep their sample rate and hit MP3’s own ceiling instead: 160 kbps at 16–24 kHz, 64 kbps for narrowband 8 kHz speech such as AMR), M4A writes AAC, and WAV is uncompressed 16-bit PCM — a faithful copy several times larger that restores nothing a lossy source threw away (MP3 to WAV says so plainly).

A common trap: movie rips and disc captures often carry Dolby Digital (AC-3) audio, which browsers cannot decode. The media library underneath does not fail on those — it silently drops the track, leaving a “successful” conversion with no sound. The engine catches any track it did not discard on purpose and hands the file to the software decoder, which reads AC-3 and downmixes 5.1 to stereo (AC3 to MP3 is the standalone version). A file with no audio track gets a plain error — “This file has no audio track to extract.” — never an empty file.

Legacy formats: AVI, FLV, WMV, 3GP, MPG, VOB

The hardware path reads modern containers only. AVI, FLV, WMV, MPG and VOB — and old audio such as WMA, AMR and AIFF — go to a second engine: a complete software decoder (ffmpeg as WebAssembly) fetched once on first use (about 31 MB) and cached by your browser; only the engine downloads, never your file. It decodes what those containers actually hold — DivX/Xvid and MS-MPEG4 in AVI, H.263, VP6 and early H.264 in FLV, WMV1/2/3 in WMV, H.263, MPEG-4 Part 2 and AMR in 3GP, MPEG-1/2 in MPG and DVD VOB — and writes H.264 with 128 kbps AAC for MP4 (VP8 with Vorbis for WebM). It runs single-threaded, a full re-encode at CPU speed: seconds for a small phone clip, minutes for a long DVD recording.

Exceptions and limits: MTS/M2TS and TS are transport streams the hardware engine reads natively, so AVCHD-framed H.264/AAC streams remux instantly — proved by the verification harness with a camcorder-framed fixture. Camcorder files carrying Dolby Digital audio take the software path below. A few very old AVIs use proprietary capture codecs even this decoder lacks; WMA Pro and WMA Lossless are not covered on WMA to MP3; MKV subtitle tracks are not carried over yet. For the codec cases the tool tells you instead of producing a broken file; subtitles are simply left out of the output.

Video to GIF, and GIF back to video

GIF output is built frame by frame on your device: 12 frames per second, at most 480 pixels wide (aspect ratio preserved, never upscaled), each frame quantized to a 256-color palette, and no audio — the format has none. GIF grows fast, so it suits moments under about fifteen seconds: trim first, then loop it with MP4 to GIF or MOV to GIF. The other way, GIF to MP4 swaps 1989-era full-frame storage for a real video codec, and the same loop typically shrinks by 90% or more.

Frequently asked questions

Why are some conversions instant?

Many files (most MKV and MOV videos, and TS/MTS recordings whose audio is already AAC) already contain MP4-compatible H.264 video. ConvertUno detects this and simply repackages the streams without re-encoding — a lossless remux that takes about as long as reading the file, even for huge ones. You will see a badge on the result when it happens.

What does the lossless badge mean, exactly?

It appears only when every stream that exists in the source was copied without re-encoding. A copied picture over re-encoded sound does not qualify — that would be a quality loss wearing a lossless label. Re-encoded results get no badge, and the verification harness applies the same rule before recording a pair as a remux.

Which formats can I convert?

Video in: MP4, MOV, WebM, MKV, M4V, TS, MTS/M2TS — plus AVI, FLV, WMV, 3GP, MPG/MPEG and VOB through the built-in software decoder. Audio in: MP3, WAV, M4A, FLAC, OGG, AAC, Opus, WMA, AIFF, AMR, CAF and AC-3. Out: MP4, WebM, MKV, MOV, GIF, AVI or WMV video, and MP3, WAV, M4A, M4R, OGG, AAC, FLAC, WMA or AIFF audio. TS, M4V, MPG, 3GP and Opus output live on their own pages in the directory below.

Is my file uploaded to a server?

No. Conversion runs entirely in your browser on your own device — there is no upload, no queue, and no server holding your files.

Is there a file size or usage limit?

None. Because your device does the work, we have no server costs to protect — no size cap, no daily quota, no signup, no watermark. Single MP4 outputs from sources of 300 MB or more stream straight to a location you pick on disk (Chromium browsers), so the result never has to fit in tab memory.

Why does my first AVI, WMV or VOB conversion download something?

Those formats need the software decoder, which the site fetches once on first use — about 31 MB — and your browser caches afterwards. It is the engine that is downloaded, never your file: the conversion still runs on your device.

What bitrate does MP3 output use?

320 kbps, the highest tier MP3 allows, on every route to MP3 from sources sampled at 32 kHz or above — whether the audio comes out of a video or another audio file, and whichever engine runs. Lower-rate sources keep their sample rate, and MP3’s own ceiling is lower there: 160 kbps at 16–24 kHz, and 64 kbps for narrowband 8 kHz speech such as AMR. If the source already carries MP3 audio it is copied out unchanged instead.

Will converting reduce my video quality?

Lossless remuxes change nothing at all. When a real re-encode is needed (e.g. WebM to MP4), the encoder tracks the source’s own data rate plus 15% headroom rather than a fixed preset — visually faithful without tripling the file. If you also need a specific file size, use the compressor instead.

Video to video: change the container

MP4, MKV, MOV, WebM, TS and the legacy formats. Compatible codecs remux instantly; the rest re-encode — on your video hardware for modern containers, in the software decoder for the legacy ones.

Convert 3GP to MP4 Convert 3GP phone videos to MP4 in your browser — free, private, no upload. Bring clips from old feature phones back to playable life.
Convert AVI to MP4 Convert old AVI videos to MP4 in your browser — free, private, no upload. Bring camcorder footage and legacy files into the modern world.
Convert AVI to WebM Convert old AVI videos to WebM in your browser — free, private, no upload. Legacy clips become embeddable, modern web video.
Convert FLV to MP4 Convert FLV (Flash video) to MP4 in your browser — free, private, no upload. Rescue clips from the Flash era into a format that plays anywhere.
Convert M4V to MP4 Convert M4V video to MP4 in your browser — free, private, no upload. Same video data, universal extension — done in seconds without re-encoding.
Convert MKV to MP4 Convert MKV files to MP4 in your browser — free, private, no upload, no size limit. Most MKVs convert instantly with zero quality loss (no re-encode).
Convert MOV to MP4 Convert iPhone and Mac MOV files to MP4 in your browser — free, private, no upload. Standard recordings convert losslessly in seconds.
Convert MOV to WebM Convert iPhone and Mac MOV videos to WebM in your browser — free, private, no upload. Camera footage becomes web-embed ready.
Convert MP4 to 3GP Convert MP4 to 3GP in your browser — free, private, no upload. Shrinks video down to feature-phone size for old handsets and slow networks.
Convert MP4 to AVI Convert MP4 to AVI in your browser — free, private, no upload. Classic MPEG-4 video with MP3 audio, the combo old players actually accept.
Convert MP4 to M4V Convert MP4 to M4V in your browser — free, private, no upload. An instant repack into Apple's extension — same video, zero quality loss.
Convert MP4 to MKV Convert MP4 video to MKV in your browser — free, private, no upload. Usually an instant, lossless repack into the archivist's container.
Convert MP4 to MOV Convert MP4 video to MOV in your browser — free, private, no upload. Usually an instant, lossless repack for QuickTime-first workflows.
Convert MP4 to MPG Convert MP4 to MPG in your browser — free, private, no upload. Real MPEG-2 output for DVD authoring tools and legacy gear that ingest nothing newer.
Convert MP4 to TS Convert MP4 to TS in your browser — free, private, no upload. H.264 sources remux losslessly into the transport stream HLS and broadcast tooling expect.
Convert MP4 to WebM Convert MP4 video to WebM in your browser — free, private, no upload. The open web format, encoded with modern VP9 on your own device.
Convert MP4 to WMV Convert MP4 to WMV in your browser — free, private, no upload. Windows Media video for the old apps and devices that still insist on it.
Convert MPG to MP4 Convert MPG/MPEG videos to MP4 in your browser — free, private, no upload. DVD rips and early digital camera clips, modernized on your device.
Convert MTS to MP4 Convert AVCHD MTS camcorder files to MP4 in your browser — free, private, no upload. Camera footage becomes editable, shareable video.
Convert TS to MP4 Convert TS transport-stream video to MP4 in your browser — free, private, no upload. TV recordings and camera clips become playable everywhere.
Convert VOB to MP4 Convert DVD VOB files to MP4 in your browser — free, private, no upload. Old discs become videos that play on anything made this century.
Convert WebM to MP4 Convert WebM to MP4 right in your browser — free, private, no upload, no size limit. Hardware-accelerated conversion for screen recordings and clips.
Convert WMV to MP4 Convert WMV to MP4 in your browser — free, private, no upload. Make old Windows videos play on phones, Macs, TVs and the modern web.

Video to audio: extract the sound

Pull the audio track out of a video as MP3, M4A, WAV or OGG — the picture is discarded, the sound stays on your device.

Convert AVI to MP3 Extract MP3 audio from AVI videos in your browser — free, private, no upload. Old recordings and clips become universal audio files.
Convert MKV to MP3 Extract the audio from MKV video as MP3 in your browser — free, private, no upload. Concerts, lectures, and interviews become listenable anywhere.
Convert MOV to MP3 Extract audio from iPhone and Mac MOV videos as MP3 in your browser — free, private, no upload. Keep the sound, drop the video.
Convert MP4 to M4A Extract MP4 audio as M4A in your browser — free, private, no upload. Usually a lossless copy of the original track, done in seconds.
Convert MP4 to MP3 Turn any MP4 video into an MP3 audio file right in your browser — free, private, no upload, no size limit. Perfect for music, lectures, and podcasts.
Convert MP4 to OGG Extract MP4 audio as OGG in your browser — free, private, no upload. Modern Opus audio in the open container the web plays natively.
Convert MP4 to WAV Extract MP4 audio as uncompressed WAV in your browser — free, private, no upload. The editing and transcription format, straight from video.
Extract MP3 audio from video Extract MP3 audio from any video right in your browser — free, private, no upload, no size limit. Works with MP4, MOV, WebM, MKV and more.
Convert WebM to MP3 Extract audio from WebM video as MP3 in your browser — free, private, no upload. Screen recordings and web clips become universal audio files.
Convert WebM to OGG Extract WebM audio as OGG in your browser — free, private, no upload. Usually an instant, lossless copy of the Opus track.

Audio to audio

Between MP3, WAV, M4A, FLAC, OGG, Opus, AAC, WMA and AIFF — including the old and awkward ones.

Convert AAC to MP3 Convert raw AAC audio files to MP3 in your browser — free, private, no upload. Streams and recorder output become playable everywhere.
Convert AC3 to MP3 Convert AC-3 (Dolby Digital) audio to MP3 in your browser — free, private, no upload. DVD-rip surround becomes stereo that plays everywhere.
Convert AIFF to MP3 Convert AIFF audio to MP3 in your browser — free, private, no upload, no size limit. Mac studio files become small MP3s that play anywhere.
Convert AMR to MP3 Convert AMR voice recordings to MP3 in your browser — free, private, no upload. Old phone memos become playable, shareable audio.
Convert CAF to MP3 Convert CAF to MP3 in your browser — free, private, no upload. Apple's Core Audio files become universal 320 kbps MP3s that play anywhere.
Convert FLAC to M4A Convert FLAC audio to M4A in your browser — free, private, no upload. Lossless masters shrunk for phones, Apple Music, and daily listening.
Convert FLAC to MP3 Convert FLAC to MP3 in your browser — free, private, no upload, no size limit. Make your lossless library playable on everything you own.
Convert FLAC to WAV Convert FLAC to uncompressed WAV in your browser — free, private, no upload. Lossless in, lossless out — bit-perfect audio for any tool.
Convert M4A to FLAC Convert M4A audio to FLAC in your browser — free, private, no upload. Apple-format audio preserved losslessly for FLAC-only tools.
Convert M4A to MP3 Convert M4A audio to MP3 in your browser — free, private, no upload. Voice memos, iTunes tracks, and recordings become universally playable.
Convert M4A to WAV Convert M4A audio to uncompressed WAV in your browser — free, private, no upload. Voice memos become editor- and transcription-ready.
Convert MP3 to AAC Convert MP3 audio to raw AAC in your browser — free, private, no upload. The stream format broadcast tools and encoders expect.
Convert MP3 to FLAC Convert MP3 audio to FLAC in your browser — free, private, no upload. Honest fact up front — FLAC preserves; it cannot restore MP3's losses.
Convert MP3 to M4A Convert MP3 audio to M4A in your browser — free, private, no upload. The format Apple's apps and audiobook workflows expect.
Convert MP3 to M4R Convert MP3 to M4R in your browser — the iPhone ringtone format, made on your device with no upload. Free, private, and ready for iTunes/Finder.
Convert MP3 to OGG Convert MP3 audio to OGG in your browser — free, private, no upload. The open, license-free format for web audio and open-source projects.
Convert MP3 to Opus Convert MP3 to Opus in your browser — free, private, no upload. The modern low-bitrate codec for Discord, bots, and podcasts at tiny sizes.
Convert MP3 to WAV Convert MP3 to uncompressed WAV in your browser — free, private, no upload. The format editors, DAWs, and audio tools expect.
Convert MP3 to WMA Convert MP3 to WMA in your browser — free, private, no upload. For the old Windows players, car stereos, and devices that only accept WMA.
Convert OGG to MP3 Convert OGG audio files to MP3 in your browser — free, private, no upload. Game sounds, downloads, and voice clips become playable anywhere.
Convert OGG to WAV Convert OGG audio to uncompressed WAV in your browser — free, private, no upload. Open-format audio made ready for any editor or tool.
Convert Opus to MP3 Convert Opus audio to MP3 in your browser — free, private, no upload. Voice messages and modern recordings become playable on anything.
Convert WAV to AAC Convert WAV audio to raw AAC in your browser — free, private, no upload. Clean streams for broadcast and encoder pipelines, from the master.
Convert WAV to AIFF Convert WAV to AIFF in your browser — lossless, free, private, no upload. The uncompressed format Mac audio and production apps expect.
Convert WAV to FLAC Convert WAV audio to FLAC in your browser — free, private, no upload. Same samples, roughly half the size — the archival format.
Convert WAV to M4A Convert WAV recordings to compact M4A in your browser — free, private, no upload. Around 85% smaller with quality kept intact.
Convert WAV to MP3 Convert WAV files to MP3 in your browser — free, private, no upload, no size limit. Shrink recordings to a quarter of the size at top quality.
Convert WAV to OGG Convert WAV audio to compact OGG in your browser — free, private, no upload. Open-format Opus audio encoded straight from the master.
Convert WMA to MP3 Convert WMA audio to MP3 in your browser — free, private, no upload. Old Windows Media Player libraries become playable on every modern device.

Video to GIF, and GIF to video

Loops built frame by frame at 12 fps and up to 480 px wide — or a bulky GIF turned back into a small MP4/WebM.

Convert AVI to GIF Turn AVI video into an animated GIF in your browser — free, private, no upload. Old clips become loops that play in any chat or page.
Convert GIF to MP4 Convert animated GIF to MP4 video in your browser — free, private, no upload. Same animation at a fraction of the file size.
Convert GIF to WebM Convert animated GIF to WebM in your browser — free, private, no upload. The open web-native video format at a fraction of GIF's size.
Convert MKV to GIF Turn MKV video into an animated GIF in your browser — free, private, no upload. A clip becomes a loop that plays anywhere, no player needed.
Convert MOV to GIF Turn iPhone MOV clips into animated GIFs in your browser — free, private, no upload. Your moment becomes a loop that plays absolutely everywhere.
Convert MP4 to GIF Turn MP4 clips into animated GIFs right in your browser — free, private, no upload, no watermark. Tuned for crisp, postable GIFs that loop anywhere.
Convert WebM to GIF Turn WebM recordings into animated GIFs in your browser — free, private, no upload. Perfect for screen captures headed to docs, issues, and chats.

Convert video to MP4 — or extract MP3