1Upload every file you want combined — at least two of them.
2Drag the uploaded items into the order you want; the order is taken from the list, not from the filenames.
3Start the merge, which joins matching inputs without re-encoding them and reconciles mismatched ones exactly once.
4Download the single combined WebM file.
Merge WebM FAQ
Does it matter if the inputs are different formats?
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It does. WebM is the royalty-free web container — VP9 or AV1 video with Opus audio, decoded natively by every modern browser. Matching inputs take a fast, lossless path; mismatched ones have to be reconciled to a common format, which is slower and costs one encode.
Anything specific to WebM when merging?
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Yes — WebM is VP9 or AV1 with Opus audio, which browsers decode natively but which most desktop editors still transcode on import. That is worth checking when the inputs did not all come from the same source.
How many files can I combine at once?
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On the free tier a merge accepts two files at a time, which is deliberately higher than the single-file limit on other tools because merging one file is meaningless. A pass removes the cap entirely.
Is the merge lossless?
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It is whenever the inputs already agree — the encoded data is copied straight through. It stops being lossless only when the inputs disagree and something has to be re-encoded to make them compatible, and even then it is one pass, not one per file.
Can I run Merge WebM on several WebM videos at once?
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Yes. Uploads queue in parallel, which matters more here than anywhere else because video jobs are minutes rather than seconds. Free accounts run one file at a time; a pass lifts that.
What happens to audio, subtitle and chapter tracks?
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They are carried across. Multi-track audio, embedded subtitle tracks and chapter markers survive wherever the target container can represent them — that is the main thing that separates a proper job from a naive re-encode that silently keeps only track one.
Does Merge WebM cost anything?
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No. Merge WebM is free without an account, and the output carries no watermark, no corner logo and no intro card. Uploaded video is deleted from the workers shortly after the job completes.
Is there a file size limit on Merge WebM?
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Yes: free accounts process video up to 1 GiB per file, by far the most generous cap on the site; ffmpeg with x264, x265 and libvpx does the work, which is the same toolchain behind most desktop video software. Video is the one family where the cap is high enough that upload time, not the limit, is what you will actually notice.
Why does a PNG site host Merge WebM?
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PNG.to is built around the format you use when you cannot afford to lose a pixel: lossless, alpha-capable, and the correct answer for screenshots, logos, line art and anything with hard edges. Image work is rarely one step: people arrive to change a format and leave needing the picture a different size, a different weight or a different shape. Running Merge WebM on the same upload pipeline, the same size caps and the same account is the whole reason it is here rather than on a fourth tab.
What should I do with the result once Merge WebM is finished?
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The converter on this site moves images to and from PNG, JPG, WebP, GIF and SVG — which is the step where the decision about transparency actually gets made. That is the step most people actually came for, and doing it after Merge WebM rather than before it means the conversion works from the file you finally settled on.
Is Merge WebM here the same tool the sibling sites run?
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The engines are shared — the same libraries, the same workers, the same limits. What differs is the advice, and the advice here starts from one fact about the format this site is named after: there is no quality slider to get wrong — a PNG round-trips bit-exactly, so the only thing edits cost you is file size. A PNG site is opinionated about where PNG is the right destination and where it is not, and that judgement is worth more than the button.
Do I need an account, and does anything get kept?
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No account, and nothing is kept: uploads are deleted from the workers shortly after the job finishes, and nothing you process is indexed, listed or used for anything else. Free accounts exist for history and batch size, not for access.
