Fix it now
- Drop the file
- Repair runs locally
- Download the result
Videos sent through WhatsApp are re-encoded to a compact, widely-compatible MP4 — H.264 video with AAC audio — so they play on almost any phone. When one won't open, the codec is rarely the problem; the file is usually incomplete or truncated: a download that stalled, a chat export or backup restore that cut off, or a copy off a phone or SD card that was pulled early. Drop the file above and the tool inspects its real structure in your browser and rebuilds or salvages what the surviving bytes allow — the video is never uploaded.
Why WhatsApp videos arrive broken
Almost every unplayable WhatsApp MP4 traces back to one of three interruptions:
An interrupted download. Tapping a received video downloads it from WhatsApp's media servers; a dropped connection or a switch away from the app mid-download can leave a partial file — the front of the MP4 arrived, the tail didn't. A truncated transfer. Moving videos off a phone over USB, via a chat export, or through a cloud/backup restore can cut a file short if the copy is interrupted. Storage trouble on the phone. A full device or a failing SD card can write an incomplete file to begin with.
An MP4 keeps a moov index — the map of every frame — that a player must read to decode the video. WhatsApp typically places this index near the front of the file so clips start fast, but a truncation still removes whatever was at the cut, and a partial file may be missing frames, the tail of the index, or both. The player's response is the same: it calls the file corrupt or shows nothing.
What can be recovered — and what can't
Where the index survived but the container is malformed, the fix is a straightforward rebuild: re-map the frames and correct the offsets so a player can read the stream again. Where the file was truncated, the tool salvages the frames that were completely written before the cut and reconstructs a playable container around them — so a clip that arrived 80% complete gives back that 80% instead of failing whole. This all runs in your browser as the file is read from disk.
The honest limit is simple: bytes that never arrived can't be recovered. If a download stopped at 60%, the last 40% of the video isn't on your device and no tool can invent it back — the real fix there is to re-download the video from the chat while you still can, or ask the sender to share it again. When the original is still available, a clean re-download beats any repair.
What this can and can't fix
Can fix
- A WhatsApp MP4 truncated by an interrupted download or transfer — frames written before the cut are salvaged
- Container damage: broken index, wrong offsets, bad timestamps in an otherwise complete file
- Videos that copied off a phone or SD card but won't play in any player
- H.264/AAC clips a recovery tool returned in an unplayable state, when the video data survived
Can't fix
- The part of a video that was never downloaded (re-download it from the chat instead)
- A download so short only a fragment of the file arrived
- Footage lost to a failing SD card or full phone storage (recover the storage first)
- Files that read as 0 bytes or mostly zeros
If a repair fails, we tell you why (missing data versus broken structure), and you are never charged for a failed repair.