Are my video clips uploaded to a server?

No. The entire merge happens inside your browser. Every clip you add is read into memory on your own device, joined locally by a WebAssembly build of FFmpeg, and the merged MP4 is handed straight back to you as a download — no byte of any clip is ever sent to us or anyone else. This is especially valuable when the footage is personal, like family events or videos of children; it never leaves your machine, and only the single merged file is produced. Close the tab and nothing is retained.

Can I mix clips of different sizes, orientations, and formats?

Yes — that is the whole point. You can combine MP4, MOV, WebM, MKV, and AVI clips of any resolution, any orientation, and any frame rate in a single merge. Every clip is fitted onto a shared 1280×720 canvas at 30 fps before joining, so it does not matter that your inputs started out different. Whatever combination you add, you get back one clean, continuous MP4 that plays virtually everywhere.

Why do some clips have black bars, and what resolution is the output?

The merged video is 1280×720 (720p), a size that plays everywhere and keeps the file reasonable. When a clip’s shape does not match — for example a portrait clip on a landscape canvas — the tool adds black bars to fit it rather than cropping, so the entire frame of every clip is preserved. This letterboxing or pillarboxing is deliberate: it guarantees you never lose part of a shot just because it was filmed in a different orientation from the others.

Why is it slow, and is the audio kept?

This is the most demanding tool in the toolkit. To join mismatched clips reliably, each one is first re-encoded to a common size and frame rate, and then all of them are encoded together into the final video — so every clip is effectively processed twice, which takes a few minutes per clip in the browser. Audio is preserved: clips that have sound keep it, and any silent clip is padded with silence so the audio stays in sync across the whole merged video. A live percentage and a Cancel button keep you in control throughout.

Is there a limit on file size?

Yes — 500 MB for the combined size of all the clips you add, not per clip. Because every clip is loaded into your browser tab’s memory together to be merged, the total has to fit comfortably, and very large batches would risk crashing the tab. Video files are larger than audio, so this limit matters more here: a handful of short clips is comfortable, while many long high-resolution clips may need to be merged in smaller groups. The running total is checked as you add files.

Convert

Merge Videos

Join several video clips into one MP4, in the order you choose, right in your browser. Mix any sizes, orientations, and formats. Nothing is uploaded. Free, no signup.

By the Samastam teamLast updated 2026-06-14

Drop video clips here, or click to browse

Clips add to the list · everything runs in your browser — nothing is uploaded

A video merger joins several separate clips into one continuous video. You add two or more clips, put them in the order you want, and the tool stitches them end to end and returns a single MP4 — entirely inside your browser. You can mix clips freely: a landscape phone video, a portrait recording, and a clip from a different camera can all go into the same merge, because each one is normalised to a common 1280×720 canvas at 30 fps and then joined. It accepts the formats people actually have — MP4, MOV, WebM, MKV, and AVI — in any combination, and always returns a widely playable MP4. Because the work happens locally, your footage never leaves your device; event clips, recorded calls, and personal videos all stay on your own machine, and only the merged file is produced.

What this is and why it matters

Video often arrives in pieces that belong together. You film one event — a wedding, a birthday, a festival — across a dozen short phone clips, and you want one video to keep or share rather than a camera roll full of fragments. A video call or a lecture was recorded in parts because the app stopped between sessions. Two people filmed the same event on two different phones, and you want their clips as one running reel. In each case the clips are fine on their own — they just need to be joined, in the right order, into a single video you can play start to finish without tapping through a list.

This tool merges in the browser rather than on a server, for the same privacy reason as the rest of the toolkit. The clips people want to join are often personal — family footage, a recorded class, videos of children — and uploading a whole batch of them to a website just to stick them together is slow and a privacy risk. Here every clip is read into memory on your own device, joined locally, and handed back as one file. Nothing is transmitted and nothing is stored.

The merge handles mismatched clips on purpose. Real footage is rarely uniform — one clip is landscape, another portrait, another from a different camera at a different size and frame rate. Rather than rejecting anything that does not match, the tool fits every clip onto a shared 1280×720 canvas, adding neat black bars where an orientation differs so no part of the frame is ever cropped away, and joins the result into one clean, widely playable MP4 — in exactly the order you arranged.

How to use this tool

Add your video clips. Drag them onto the drop zone above, or click to browse — either way, clips are added to a list rather than replacing what is already there, so you can add a few, then add more. MP4, MOV, WebM, MKV, and AVI are all accepted, in any mix. The combined size of all the clips must stay under 500 MB. Nothing uploads — everything happens on your own machine.

Put them in order. The clips merge top to bottom in the order shown. Use the up and down controls on each row to move a clip earlier or later, and remove any clip you did not mean to add. Take a moment to get the order right, because that is exactly how the final video will play.

Let the engine load on first use. The first time you merge, the tool downloads a one-time engine of about 30 MB into your browser. This happens only once — afterwards it is cached and later merges start immediately.

Merge and download — and expect a wait. Once you have at least two clips in the right order, press Merge. This is the heaviest tool in the toolkit: each clip is first normalised to a common size and frame rate, then all of them are joined, so plan on a few minutes per clip. A live percentage shows progress across the whole job and you can cancel at any time. When it finishes, it shows how many clips were joined and the size, and offers the merged MP4 for download.

Examples and use cases

Joining phone clips from one event

A Mumbai user filmed a cousin’s wedding across fifteen short clips on their phone — some held landscape, a few shot portrait. They add all of them, arrange them in the order the evening unfolded, and merge them into a single MP4 they can save and share with family. The portrait clips get neat black side bars rather than being cropped, so no part of any shot is lost, and the whole evening stays on their own phone instead of being uploaded to a website.

Stitching a recorded call or lecture

A Pune student recorded a two-hour online class in three parts because the meeting app restarted between sessions. The parts came out of different apps in slightly different formats and sizes. They add all three, order them correctly, and get one continuous video to revise from, with the clips reconciled onto a common canvas and the audio kept in sync — and the entire recording stays on their own laptop.

Combining clips from two phones

At a Chennai birthday, two relatives filmed on two different phones. Afterwards one person gathers the best clips from both into a single running reel. They arrange the clips in the order things happened, merge them, and end up with one video to send to the family group — no folder of separate files to scroll through, and nothing uploaded anywhere.

Assembling clips for a small business

A Jaipur shop owner has a few short product clips — some with spoken description, some silent — and wants them as one video for their catalogue. They add the clips, order them, and merge. The silent clips are padded with silence so the sound from the spoken ones stays aligned, and the result is one clean MP4 processed entirely on their own device, keeping unreleased product footage private.

Frequently asked questions

Are my video clips uploaded to a server?: No. The entire merge happens inside your browser. Every clip you add is read into memory on your own device, joined locally by a WebAssembly build of FFmpeg, and the merged MP4 is handed straight back to you as a download — no byte of any clip is ever sent to us or anyone else. This is especially valuable when the footage is personal, like family events or videos of children; it never leaves your machine, and only the single merged file is produced. Close the tab and nothing is retained.
Can I mix clips of different sizes, orientations, and formats?: Yes — that is the whole point. You can combine MP4, MOV, WebM, MKV, and AVI clips of any resolution, any orientation, and any frame rate in a single merge. Every clip is fitted onto a shared 1280×720 canvas at 30 fps before joining, so it does not matter that your inputs started out different. Whatever combination you add, you get back one clean, continuous MP4 that plays virtually everywhere.
Why do some clips have black bars, and what resolution is the output?: The merged video is 1280×720 (720p), a size that plays everywhere and keeps the file reasonable. When a clip’s shape does not match — for example a portrait clip on a landscape canvas — the tool adds black bars to fit it rather than cropping, so the entire frame of every clip is preserved. This letterboxing or pillarboxing is deliberate: it guarantees you never lose part of a shot just because it was filmed in a different orientation from the others.
Why is it slow, and is the audio kept?: This is the most demanding tool in the toolkit. To join mismatched clips reliably, each one is first re-encoded to a common size and frame rate, and then all of them are encoded together into the final video — so every clip is effectively processed twice, which takes a few minutes per clip in the browser. Audio is preserved: clips that have sound keep it, and any silent clip is padded with silence so the audio stays in sync across the whole merged video. A live percentage and a Cancel button keep you in control throughout.
Is there a limit on file size?: Yes — 500 MB for the combined size of all the clips you add, not per clip. Because every clip is loaded into your browser tab’s memory together to be merged, the total has to fit comfortably, and very large batches would risk crashing the tab. Video files are larger than audio, so this limit matters more here: a handful of short clips is comfortable, while many long high-resolution clips may need to be merged in smaller groups. The running total is checked as you add files.