Crossfade, gap or straight cut: which to use
The setting that matters most is what happens at each join. The tool offers three, and the right one depends on what you are joining.
| Join | Setting | Best for |
|---|---|---|
| Straight cut | Crossfade 0, Gap none | Podcast segments, voice memos and lecture parts that should run on |
| Crossfade 2–5 s | Crossfade slider | Songs for a mix, a wedding or party playlist, ambient or lo-fi tracks |
| Crossfade 0.5–1 s | Crossfade slider | Hiding a click where two clips of the same recording are joined |
| Silent gap 1–3 s | Gap slider | Album-style tracks, spoken-word chapters, a practice tape with pauses |
The crossfade is equal-power: one track fades out on a cosine curve while the next fades in on a sine curve, so the combined level stays steady instead of dipping in the middle. If a gap is set, it replaces the crossfade, and the crossfade slider switches off. If two files are very short, the overlap is capped at half of the shorter one.
Match loudness between files
Files from different sources rarely have the same volume: a phone recording next to a mastered song, or two songs from different years. Tick Match loudness and each file is scaled so its average level lands in the same place, with a safety limit that stops any file from clipping. The change applies to the preview and the download alike.
This is a simple average-level (RMS) match, not a broadcast loudness standard. It gets files close, not identical, so for a tight podcast mix, still listen through the joins. If the files already sound even, leave it off and nothing is changed.
What you can join
- Songs: build a medley, a gym playlist as one file, or a continuous DJ-style mix.
- Voice recordings: stitch voice memos, interview parts or lecture takes into a single recording.
- Video soundtracks: drop MP4 or MOV files and only the sound is used, so you can join the audio of several clips.
- Mixed formats: MP3, WAV, M4A, FLAC and OGG can be in the same list, whatever your browser can decode.
Need to remove a cough or the silence at the start of one file first? Cut it in the Audio Cutter, save it, then add the trimmed file here. The joined result is a normal MP3 or WAV, so you can open it next in the pitch changer, the BPM finder or the vocal remover.
Why join audio in the browser
Many online mergers upload each file to a server before joining it. This one decodes and mixes the files with the Web Audio API on your own device and encodes the MP3 there too, so private recordings stay private, a long list is ready in seconds, and there is no watermark or daily limit.
The trade-off is memory. Decoded audio is large, so the total is capped at 20 minutes and 20 files. For longer jobs, join in two batches and then join the two results. Saving as MP3 re-encodes the audio once at 256 kbps; choose WAV if you plan to edit the joined file further and want to avoid a second lossy step.
Frequently asked questions
Is this audio joiner free?
Yes. Joining, previewing and downloading are free with no sign-up, no watermark and no daily limit.
Are my files uploaded anywhere?
No. The files are decoded, joined and encoded in your browser. Nothing is sent to our servers.
How many files can I merge?
Between 2 and 20 files, with a combined length of up to 20 minutes. That keeps the joined copy within what a phone or laptop browser can hold in memory.
How do I change the order of the files?
Drag a row to a new position, or use the up and down arrow buttons on each row, which also work on a phone.
Can I add a crossfade between songs?
Yes. The Crossfade slider goes from 0 to 5 seconds. The two tracks overlap and fade on an equal-power curve so the volume stays steady through the transition.
Can I merge MP3 and WAV files together?
Yes. Mixed formats are fine. Files at different sample rates are converted to match the first file, and mono files are joined with stereo ones.
Can I join the audio from videos?
Yes. Drop MP4 or MOV files and their sound tracks are used as audio. The output is audio only (MP3 or WAV), not a joined video.
Does saving MP3 lower the quality?
Saving as MP3 re-encodes the joined audio once at 256 kbps, which is hard to tell from the originals for most listeners. Choose WAV for a 16-bit lossless file.
Can I trim the files before joining?
Not inside the joiner. Trim each file with the Audio Cutter, download it, then add the trimmed files here.