Will this QR code ever expire or stop working?

No. It is a static code — the destination is encoded in the pattern itself, not stored on any server. There is no redirect to break, no account to lapse and no subscription to end. It works for as long as whatever it points to still exists.

Do I need to sign up or pay?

No. There is no account, no email capture, no free trial and no paid tier. The generator runs entirely in your browser — the text you type never leaves your device, and nothing is stored.

Can I edit the code after printing it?

Not the code itself, and that is the point — an editable code is one someone else can also switch off. If you need to change the destination later, encode a URL on a domain you control and change what that page does.

Why did my old QR code stop working?

Almost always because it was a dynamic code routed through a generator's short link, and that redirect was disabled when a trial or subscription ended.

No, and it cannot. Tracking requires routing every scan through a server first, which is exactly the thing that makes a code able to expire. You get no analytics — and in exchange, nothing in the middle can fail.

Guide

Why won't my MP4 play?

The file is there. It's the right size — hundreds of megabytes, sometimes gigabytes. But every player refuses it, or opens it and jumps straight to the end. In most cases the footage is still inside and perfectly intact. What's missing is something much smaller.

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Check your video nowFree and instant. Runs in your browser — the file is never uploaded.

The short answer

An MP4 keeps the picture and the directions to the picture in two separate places. Cameras write the picture continuously while recording, and only write the directions when you press stop. If the recording never got a proper stop — flat battery, card yanked out, phone crash — you're left with a big file full of footage that no player can navigate.

It looks like the video is gone. Usually 99% of it is right there.

How an MP4 is actually built

An MP4 is a series of labelled sections laid end to end. Two of them matter here:

mdat — the media data. The actual picture and sound. This is essentially the entire file size.
moov — the index. A list saying "frame 1 starts at this byte and is this long, frame 2 starts here…" for every frame. Usually well under 1% of the file.

A player reads moov first. Without it, it has no idea where any frame begins, and it will not guess. So a 4 GB file missing a 2 MB index is, to a player, unopenable — even though the footage is untouched.

Why write the index last? Because you can't know how long the recording will be until it ends. So the camera streams footage into mdat as it records, and writes moov at the end. Interrupt that final step and you get exactly this problem.

The three faults, and how to tell them apart

1. The index was never written

The classic interrupted recording. The file is large, players report it as corrupt or unsupported, and nothing at all appears. Nothing is missing except the index.

The fix: a free tool called untrunc rebuilds the index by studying a working video from the same camera at the same settings, then applying that structure to your broken file. The reference clip matters — same device, same resolution and frame rate. Shoot a fresh ten-second clip on that camera if you don't have one.

2. The index doesn't match the footage

This one looks stranger. The player opens the file, shows the correct duration, gives you a full scrub bar — and then jumps to the end without displaying a single frame. Or it plays a burst of garbled colour and stops.

Here the index exists and is internally consistent, but the frames aren't where it says they are. This is the fingerprint of a file that has been through recovery software. Video files are often stored in scattered pieces across a disk, and when a recovery tool reassembles one it can pick the pieces up in the wrong order. What comes out is structurally valid and completely unwatchable.

The fix: there usually isn't one for the file itself — the picture data in it genuinely belongs somewhere else. The realistic move is to go back to the original source and recover it again with a tool that handles fragmentation properly.

3. The file was cut short in transit

An interrupted download, a copy that ran out of space, or a transfer from a card that was removed mid-write. The index survives and points confidently at data that simply isn't there any more, because the tail of the file is missing.

The fix: copy it again from the original. Everything up to the cut-off point is usually fine, so a player will often show the opening minutes before stopping abruptly.

Find out which one you have

These three faults need completely different responses, and guessing wastes time — people spend hours running repair software on a file that has no footage left to repair. Reading the file's structure tells you in a second which one you're dealing with.

Our video file checker does exactly that, in your browser, without uploading anything. Drop the file in and it reports whether the index is missing, whether it disagrees with the footage, or whether the file is simply cut short.

Things that are worth trying first

Before assuming the worst, rule out the boring explanations:

Try VLC. It's free and far more tolerant than Windows' or macOS's built-in players, which give up on anything slightly unusual. A surprising number of "broken" files play fine in VLC.
Check it finished copying. Compare the file size against the original. A file that's short by a few megabytes was cut off in transit.
Play it on the device that made it. If the camera or phone still shows it, the file on your computer is the damaged copy, not the original.
Check the extension is honest. A file renamed to .mp4 from something else won't play, and no repair tool will help.

What not to do

Don't keep recording on the memory card the video came from. If the file is damaged and you may need to recover the original, every new recording risks writing over it. Take the card out and leave it alone until you've decided.

Be sceptical of paid "video repair" products that promise to fix anything. They mostly do what untrunc does free, and none of them can restore footage that isn't there. Find out which fault you have first — for two of the three, no repair tool can help, and knowing that saves both the money and the afternoon.

Frequently asked questions

Is my footage actually still in the file?

If the file is close to the size you'd expect for its length, yes — almost all of it is media data. A missing index costs you under 1% of the file, so a large unplayable file is nearly always full footage with no directions.

Will re-downloading or re-copying help?

Only for fault 3, where the file was cut short in transit. If the original itself is missing its index, every copy will have the same problem — the fault is in the file, not the transfer.

Can I fix it by changing the file extension?

No. The extension is just a label; players read the actual structure. Renaming .mov to .mp4 changes nothing, because both already use the same underlying format.

Why does my player show the right duration if the video is broken?

Because duration comes from the index, and the index can be perfectly readable while pointing at the wrong data. That combination — right duration, no picture — is the signature of fault 2.

Does converting it to another format fix it?

No, and it can waste hours. A converter has to decode the video first, which means it needs the same index the player couldn't find. Repair has to come before conversion.

Is the checker safe to use with private videos?

Yes. It reads the file directly in your browser and nothing is uploaded — there's no server involved at all. You can disconnect from the internet and the page still works.