Your files stay on your device. Nothing is uploaded to our servers — the media is read, combined and exported entirely inside this browser tab.
Click or drag videos, audio and images here
MP4, MOV, MKV, WebM, MP3, M4A, WAV, OGG, FLAC, PNG, JPEG, WebP — nothing leaves your browser
How the Media Merger works
Free Online Video, Audio and Image Merger
Join videos, audio files and still images into one file, in the order you choose, without installing anything and without uploading a single byte. Arrange the clips, fade them in and out, pick a format and download the result as video or as audio only.
Everything runs inside your browser using WebCodecs, so your files never leave your computer.
Instructions
How to merge videos, audio and images
Click the upload area or drag your files onto it. Each file is read locally to find its length, resolution and codecs, and then appears in the list. Press "Merge and download video" for a single video file, or "Merge and download audio" for the soundtrack alone.
Adding still images
Drop a PNG, JPEG, WebP, GIF, AVIF or BMP into the queue and it becomes a clip like any other. An image has no length of its own, so you set it: each image row has a "Show for" field, five seconds by default. Use "Add sound" on the row to give the image a soundtrack — a music file, a narration, or a video you only want the audio from. Attaching sound sets the image to the length of that sound, which is almost always what you want, and you can still change it afterwards. If you shorten it, the sound is cut at the image's end; if you lengthen it, the rest plays as silence. The image itself is never stretched: it is centred in the frame with black bars wherever the aspect ratio differs, so a portrait photo between two landscape clips lands upright and uncropped.
Fading clips in and out
Every row has two checkboxes, "In" and "Out". The pair at the top of the list ticks or unticks the whole queue at once, and shows a dash when only some clips are faded. A fade lasts one second by default; change it in the "Fade length" field, which applies to every fade in the merge.
A fade always covers both halves of a clip at once. The picture eases out of and back into black — video frames and still images alike — and the sound eases out of and back into silence at the same moment, whether it is a music file, the soundtrack of a video, or the audio you attached to an image. The audio ramp is applied sample by sample rather than packet by packet, because holding one volume across a twenty-millisecond packet turns a smooth fade into a staircase you can hear as clicks. A clip too short for two full fades splits itself in half so the two ramps meet instead of overlapping, and no fade ever spills into the clip next to it.
How to change the order
Drag any item by the handle on the left, or use the up and down arrows on each row. The order in the list is exactly the order in the finished file — the first clip plays first. Remove a single file with the "X" on its row, or empty the list with "Clear all".
Mixing video, audio-only files and images
An audio file placed between two videos keeps its full length and plays over a black screen, so nothing is silently dropped and the timeline never jumps. A video without a soundtrack plays over real silence rather than a gap, which keeps every later clip in sync — and the same goes for an image with no sound attached.
Different resolutions and frame rates
Clips rarely match. Choose a picture size — or leave it on "Match the largest clip" — and every clip is fitted into that frame with black bars where the aspect ratio differs. Nothing is cropped and nothing is stretched. The frame rate and the sample rate are normalised the same way, which is what stops audio from drifting away from picture over a long merge.
Which format should I pick
MP4 with H.264 and AAC plays on practically everything and is the right default. WebM with VP9 and Opus produces smaller files but is refused by some older players and editors. MKV is a flexible archival container, and MOV is what Final Cut and Premiere expect on macOS. For audio, M4A is small and universal, MP3 is the most portable format there is, OGG/Opus gives the best quality per kilobyte, and WAV is uncompressed — about 10 MB per minute.
Large files and saving to disk
When your browser supports it, you are asked where to save before the merge starts, and the result is written straight to that file as it is produced instead of being held in memory. That is what makes merging hours of video possible. If the dialog is dismissed or unavailable, the finished file is downloaded normally.
How merging works
Merging media is not the same as merging documents. Two video files cannot simply be placed one after the other: each carries its own timeline, its own resolution and its own encoding, and a player has no way to guess where one ends and the next begins. The clips have to be decoded, placed on a single new timeline and encoded again into one container.
That is what this tool does. Each clip is decoded frame by frame, every timestamp is shifted by the total length of the clips before it, and the frames are handed to a single encoder that writes one continuous track. Because picture and sound are shifted by the same amount, they stay locked together no matter how many clips you join.