Audio Joiner – Merge MP3 Files and Songs Online

Combine multiple audio tracks in any order, trim each one, blend transitions with an adjustable crossfade, and export locally as MP3, WAV, FLAC, M4A/AAC, or Ogg Opus.

Drop in several audio files, reorder them by dragging or with the move buttons, trim each one's own start and end point independently, and set how much adjacent clips should overlap and blend into each other. The result plays back and downloads as one continuous file, with the overlap handled by an equal-power crossfade rather than a hard, audible splice.

How to merge MP3 files

  1. Drop your MP3s — or WAV, FLAC, M4A/AAC and Ogg files — on the drop zone, or click Choose audio files; each track is decoded and gets its own waveform card.
  2. Arrange the order by dragging a card or pressing its ↑ and ↓ buttons, and use the trash icon to take a track out.
  3. Type a Start and End time on any card to trim that track, then set the crossfade anywhere from 0 to 5 seconds, where 0 means a clean cut.
  4. Pick MP3 (128–320 kbps), WAV, FLAC, M4A/AAC or Ogg Opus, click Join & create audio, listen to the preview and download the file.

How tracks are stitched together

Every source is decoded and, if its sample rate doesn't already match, resampled to a common 48kHz rate before joining — mixing tracks recorded at different sample rates together only works once they share one. Each track's own start and end trim points are validated independently: a trim needs to be at least 0.01 seconds long and fall within the source's actual duration, or the join is rejected before any audio processing happens.

The crossfade between two adjacent clips uses a sine/cosine equal-power curve rather than a straight linear fade, which avoids the brief volume dip a linear crossfade produces at its midpoint. The crossfade length you set is automatically capped at half the length of whichever adjacent clip is shorter, so a long crossfade setting can never eat into audio that isn't actually there.

Formats you can combine in one join

Mono and stereo mixed in one project

Output channel count is decided automatically: it's stereo if any source track is stereo, mono only if every source track is mono. A mono source being joined into a stereo output has its single channel copied across both output channels rather than being left silent on one side. During an overlapping crossfade region, both tracks' samples are summed and then clamped to the valid ±1 range, which keeps the sum inside what the output format can store; any peak that would have gone past full scale is flattened at the limit instead.

Export options

Merging happens in your browser tab

The joiner decodes each song, applies your trims and crossfades, and encodes the finished file inside the page itself, so the tracks you combine are never sent to a server. Without an upload step there is no server-imposed size cap either; the real ceiling is how much decoded audio your device's memory can hold, since every track stays loaded as raw samples while you arrange the order.

What a crossfade can't fix

A crossfade smooths the transition between two clips, but it can't make two mismatched sources sound like one recording — different room tone, different loudness, or a different voice or instrument timbre will all still be audible across the join, just without a click. If your source clips vary a lot in loudness, running them through the Audio Volume Changer first, before joining, will produce a much more consistent result than relying on the crossfade alone.

Joining produces up to 15 free exports per day, and Pro has no daily ceiling.

Questions people ask about Audio Joiner & Crossfade Mixer

Which audio formats can I merge?
WAV, MP3, FLAC, M4A/AAC and Ogg files, including Opus, can sit in the same project in any combination. The merged result is a single file in whichever output you choose — MP3, WAV, FLAC, M4A/AAC or Ogg Opus — no matter what the individual tracks started as.
Are my files uploaded?
No. Decoding, trimming, crossfading and encoding all run on your own device, and the merged file is handed to you as a local download. Even the counter behind the 15-per-day free allowance is kept in your browser's storage rather than on a server.
Can I merge songs on my phone?
Possibly; it depends on the phone's browser rather than on this page. Decoding needs Web Audio support, M4A/AAC and Opus exports need the WebCodecs audio encoder, and several long songs loaded together can use up a phone's memory. If dragging a card doesn't respond to touch, the ↑ and ↓ buttons reorder tracks as well.
Can I fade out the last track?
Not in the joiner. Its crossfade only blends neighbouring tracks, so the first track starts and the last one ends without any fade. Export the merged file as WAV, open it in the Audio Volume Changer, set a fade-out of up to 5,000 ms there, and save your final format from that tool.
Can I join a WAV file recorded at 44.1kHz with an MP3 recorded at 48kHz?
Yes. Every track is resampled to a shared 48kHz rate before joining, so mismatched source sample rates are handled automatically and don't need to match going in. You won't notice any difference in playback quality from this internal resampling step.
What's a reasonable crossfade length?
The default of 0.4 seconds works well for most music and voice joins — long enough to mask a hard edit, short enough that it doesn't sound like a deliberate fade effect. For spoken-word content with silence between clips, a shorter crossfade around 0.1 to 0.2 seconds usually sounds more natural.
Why does the joined file sound louder at the overlap than the original clips?
During a crossfade, both clips are playing simultaneously and their samples are added together, which can approach the maximum volume even though each individual clip was comfortably below it. The tool clamps the combined signal at full scale, so samples never wrap around, but if both source clips are already close to full volume the overlap can clip slightly and sound noticeably fuller than the rest of the track — lower them first with the Audio Volume Changer.
Can I join more than two files?
Yes, there's no fixed limit on the number of tracks — add as many as you need, reorder them into the sequence you want, and the same crossfade setting applies between every consecutive pair in the list. Practical limits come only from your browser's available memory when decoding many long files at once.

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Content reviewed 2026-09-27.