Join video clips
Most shorts are three or four takes, not one. Put them in order and get a single video back — without opening an editor.
Everything happens inside your browser, using your own computer’s memory. Your file is never uploaded, never stored, and nothing is sent to us — so there is no limit on how often you use this.
How joining clips works
At a glance
- Opens
- Two or more videos at once — MP4, MOV, WebM, MKV
- Saves
- One MP4 — H.264 video, AAC stereo sound
- Shapes
- Vertical 1080 × 1920, vertical 720 × 1280, or the first clip's own
- Mixed clips
- Upright, sideways and silent clips can be joined together
- Order
- Set it with the arrows; the top clip plays first
- Quality
- Re-encoded once at CRF 23, 30 frames a second
How it works
Clips from the same phone still differ more than you would think: one filmed upright, one sideways, one with the sound switched off, one at a different frame rate. A simple join refuses all of those. So before anything is joined, every clip is brought to the same shape, frame rate and sound format.
Each clip is scaled to fit the frame you picked and centred, with bars where it does not reach — never stretched. Sound is converted to the same 48 kHz stereo, and a clip with no sound at all is given silence of exactly its own length, so the voices in the other clips stay in sync. Then the clips are joined end to end into one file.
Step by step
- Choose your clipsSelect two or more files at once in the file picker, or drop them together. Nothing uploads.
- Set the orderThe top clip plays first. Use the arrows to move a clip up or down — lead with your strongest moment.
- Pick the shapeVertical 1080 × 1920 for posting; 720 × 1280 when you want it about twice as fast; or keep the first clip's shape.
- Join and downloadKeep the tab open — every frame is rebuilt. The finished file stays in this browser until you press Delete.
Which setting for which job
| If you are… | Choose |
|---|---|
| Three or four takes for one Reel, TikTok or Short | Vertical 1080 × 1920 |
| A quick draft to check the order | Vertical 720 × 1280 — about twice as fast |
| Clips all filmed the same way, sideways | Same as the first clip |
| One clip was filmed without sound | Nothing special — it gets silence of its own length |
| You want transitions, captions or music | Not this tool — that is editing; see how Ruzz edits |
Under the hood
The technical detail, for anyone who wants to know exactly what happens to their file. Each line first says it plainly.
Normalising before the join
Every clip made alike first.
Each video stream is scaled to fit (force_original_aspect_ratio=decrease), padded to the frame and centred, given square pixels (setsar=1), set to 30 fps and 8-bit 4:2:0 colour. The concat filter only joins streams that match exactly.
Letterboxing, not stretching
Bars rather than distortion.
A clip that does not match the frame's shape keeps its own proportions and gets black bars — above and below for a sideways clip in a vertical frame.
Sound: 48 kHz stereo
One sound format for every clip.
Each clip's sound is resampled to 48 kHz and made stereo, so a mono phone clip and a stereo one can sit side by side.
Silence for silent clips
Why a clip with no sound does not break it.
The join needs a sound track from every clip. A clip without one gets a generated silent track (aevalsrc) cut to its exact length, so the sound in the clips after it stays in sync.
Concat filter
One continuous file.
The prepared clips are joined end to end in a single pass and encoded once: H.264 (libx264, veryfast, CRF 23) with AAC sound at 128 kbps, index moved to the front for instant playback.
Platform specs
How long each platform lets a video run. Check the total length of your clips before you join them.
| Platform | Shape | Resolution | File size | Length | Format |
|---|---|---|---|---|---|
| Instagram Reels | 9:16 | 1440 × 2560 recommended | Up to 4 GB | Up to 15 minutes | MP4 or MOV · H.264 · AAC stereo, 128 kbps or more |
| TikTok | 9:16 recommended | 540 × 960 or larger | Up to 500 MB | — | MP4, MOV, MPEG, 3GP or AVI |
| YouTube Shorts | Vertical or square | — | — | Up to 3 minutes | — |
From each platform's own published specifications (Meta Ads Guide, TikTok Ads video specifications, YouTube Help), checked September 2026. “—” means the platform does not state it. Platforms change these; check before a big campaign.
If something goes wrong
| What you see | Why | What to do |
|---|---|---|
| Only one clip was picked up | The file picker was used to choose one file at a time. | Press “Choose another”, then select all the clips together (Ctrl or Cmd-click, or drag a box around them). |
| It runs out of memory | All the clips are held in the browser at once; several minutes of 4K is more than a page is given. | Pick 720 × 1280, compress the clips to 1080p first, or keep the total under about 300 MB on a phone. |
| A sideways clip has black bars | It is fitted, not stretched, into the vertical frame. | Crop it to 9:16 with Crop first (or use its blurred-backdrop option), then join. |
| It takes a long time | Every frame of every clip is rebuilt on one CPU thread. | Use 720 × 1280 for drafts; it is about twice as fast. |
Privacy: your file stays on your computer
Joining clips means holding all of them at once. Your browser holds them on your own computer — none of the takes is uploaded.
- What your browser downloads
- The page — and, the first time you use a video tool, the video engine: about 32 MB, then kept in your browser's cache.
- What it sends to us
- Nothing. There is no upload step, no copy on our servers and no account. The work happens in your computer's memory.
- How we know
- Our automated tests run every tool while recording every network request the page makes. A single upload fails the test.
- Where the result lives
- In this browser only, until you press Delete. A finished file is still here if you close the tab and come back; a job still running stops when the tab closes.
Questions
How many clips can I join?
As many as your browser's memory allows. On a laptop, a few minutes of phone video in total is comfortable; on a phone, keep it under about 300 MB.
Can I mix vertical and horizontal clips?
Yes. Each one is fitted into the shape you pick, with bars where it does not fill the frame. Nothing is stretched.
One clip has no sound. Will it break?
No. It gets silence for its own length, so the sound of the other clips stays in sync.
Can I add transitions or music?
Not here — the clips are joined straight, cut to cut. Transitions, captions and music are editing.
Is anything uploaded?
No. The clips are joined in your browser, using your computer's memory.
A tool makes a file fit. It does not make people watch to the end — that is the hook, the order of the shots, the captions and the music. See how Ruzz does it.
Other free tools
Compress video
Too big to upload, email or text? Make it small enough, without it looking bad. Takes a few minutes.
Convert format
Will not play or upload? Turn an iPhone MOV/HEVC, WebM or MKV into an MP4. Often seconds, with no quality loss.
Crop to 9:16
Turn a landscape or square video into a vertical short for Reels, TikTok and Shorts.
Trim video
Cut the dead air off the start and end, or keep just the 30 seconds that matter.
Extract audio
Pull the sound out of a video as MP3, WAV or AAC.
Grab a cover frame
Pick any moment and save it as a vertical cover image.
Video to GIF
Turn a moment into a GIF with real colours, not the grainy web palette.
Compress image
Shrink and resize a photo to JPG, WebP or PNG. Instant.
Change speed
Slow motion or sped up, from 0.5× to 2×, with voices at their own pitch.
Remove sound
Take the audio off a video in seconds, picture untouched — then add a trending sound in the app.
Resize video
Exactly 1080×1920, 1080×1350, 1080×1080 or 1920×1080 — the size each platform asks for.