Audio Joiner

Audio Joiner puts several recordings together into one file. Stitch the parts of a podcast or lecture back together, build a running order for a party or a workout, join voice notes from a chat into one message, or put an intro and outro either side of an episode.

Each clip gets its own small waveform with handles, so you can cut a slow start or a long ending off before joining, without opening another tool. Drag clips by their grip to change the order, choose a crossfade so one blends into the next, or leave a short silence between them. The timeline shows exactly how long the finished file will be, and you can preview the joins before saving.

Clips do not need to match. A 22 kHz mono voice memo, a 48 kHz stereo MP3 and the soundtrack of a phone video can go in the same file: rates and channels are matched for you. Tick “Even out loudness” and quiet clips are brought up to match the others without clipping. Everything happens in your browser; nothing is uploaded.

1. Press “Choose files” or drop two or more audio or video files on the box. Each one appears as a row with its waveform once it has been read.
2. Put the clips in order by dragging the grip on the left of a row, or with the up and down arrows. Drag the handles on a clip’s waveform to trim its start or end, and press its play button to check it.
3. Under “Between clips”, choose Straight on, Crossfade or Gap, and pick how long. Tick “Even out loudness between clips” if some recordings are much quieter than others.
4. Pick a format under “Save as” (MP3 is the default) and press “Preview the join” to listen, or tap the timeline to hear a particular join.
5. Press the Join button (it shows how many clips, such as “Join 3 clips”), then download your file. You can play it on the page first.

• Join 2 to 50 clips in one go: MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF and the sound from MP4, MOV, WebM and MKV videos.
• Trim handles on every clip’s own mini waveform, with keyboard control (arrow keys, Shift for whole seconds).
• Drag to reorder with a mouse or a finger, plus up and down buttons.
• Straight joins, smooth equal-power crossfades from 0.25 to 8 seconds, or silent gaps from 0.25 to 10 seconds.
• Even out loudness: every clip is set to the same level, as loud as they can all go without clipping.
• Different sample rates and mono or stereo files are matched automatically, using the browser’s own high-quality resampler.
• A live timeline showing each clip, the overlaps and the total length; tap it to preview from any point.
• Save as MP3, M4A, OGG, WAV or FLAC, with optional fade in and fade out for the whole file.

• For music, a 2 to 3 second crossfade sounds like a DJ mix. For speech, use Straight on or a short gap of half a second.
• Trim each clip before you join rather than afterwards: it is easier to find a clean edge on a short waveform.
• Use “Even out loudness” when one clip was recorded on a phone and another in a studio. Leave it off for music you want to keep exactly as mastered.
• Joining in a lossless format (WAV or FLAC) and converting once at the end keeps the most quality if you plan to edit further.
• Everything is held in memory while you work, so on a phone keep the total under an hour or so.