File A Choose File A

File B Choose File B

🔒 Files are processed privately and automatically deleted within 24 hours.

How should they combine?

Play one after another (A then B) Play together (B overlaid onto A) Crossfade (A fades out as B fades in)

Gap between them (seconds)

What Is an Audio Merger?

An audio merger combines two separate audio files into one. There are a few common ways to do it: play them back-to-back in sequence, overlay them so both play at the same time — like layering background music under a voice recording — or crossfade between them, so the first fades out as the second fades in.

Our merger supports all three. Choose "play one after another" for a simple combination with an optional pause in between, "play together" to mix a second track starting at any point in the first, or "crossfade" for a smooth, gradual transition — the go-to choice for podcast intros and song mashups.

What You Get

🔗 Merged Track

One audio file combining both of your uploads, ready to download as MP3.

Who Uses an Audio Merger?

🎙️

Podcasters

Stitch an intro clip onto the start of an episode, or lay theme music under an interview.

🎬

Video Editors

Combine a voiceover with a background track before dropping the audio into a video project.

🎧

DJs

Join two clips into one file for a quick mashup or transition test.

📚

Educators

Combine narration with a music bed for a class presentation.

How to Merge Two Audio Files

Upload Both Files

Choose File A and File B. Supports MP3, WAV, FLAC, M4A and more.

Pick How They Combine

Sequential with a gap, overlaid starting at a chosen time, or crossfaded smoothly between the two — drag directly on the waveforms to fine-tune concat/overlay timing.

Download the Result

Download the merged MP3.

Getting the Timing Right

For a podcast intro, sequential mode with a 0-second gap gives a clean cut straight into the episode; a 1-2 second gap adds a small breathing pause that can feel less abrupt.
Overlay mode automatically lowers both tracks slightly together to avoid clipping when they're combined — it doesn't selectively duck the background under the voice, so if a music bed still feels too loud relative to narration, reduce the music's level with our Volume Adjuster before merging.
If your two clips are at noticeably different volumes and the balance matters, adjusting each one individually beforehand gives you more predictable control than relying on the merge step alone.
Overlaying a clip that needs to line up with a specific moment in the other track (like sound effects hitting a beat) may take a couple of tries to get the offset exactly right — that's expected, and each attempt only takes seconds to re-render.
For a podcast intro or song mashup, crossfade usually sounds more natural than a hard cut or a silent gap — a 2-4 second crossfade is a good starting point for most music and voice transitions; shorter (0.5-1s) works better for quick beat-matched transitions between songs.
The crossfade duration can't be longer than either file — if you get an error about that, shorten the crossfade or trim one of the files first with our Audio Trimmer.

Frequently Asked Questions

Is the audio merger really free?

Yes, completely free. No trial period, no credit card, no catch.

What's the difference between the three modes?

"Play one after another" plays File A completely, then File B (with an optional silent gap in between). "Play together" starts File B at a specific time within File A, and both are audible at once from that point. "Crossfade" plays File A, then smoothly fades it out while File B fades in over a duration you choose, so the transition overlaps instead of cutting sharply or leaving a gap.

How long can the crossfade be?

Up to 30 seconds, but it can't be longer than either file — a crossfade can't outlast the audio it's blending between. If your crossfade duration is too long for one of your files, you'll get a clear error telling you which file and how long it actually is.

Can File B be longer than File A?

Yes. In overlay mode, if File B extends past the end of File A, the merged output simply continues until File B finishes — nothing gets cut off.

Why don't I see waveforms to drag?

Waveforms are decoded locally in your browser for both files and work for most audio formats. They're not shown for video files (the audio track inside a video container usually can't be decoded this way in the browser) or for audio formats your specific browser can't decode. Either way, the gap/offset number fields below still work exactly the same — you just won't have a waveform to drag on.

What audio formats can I upload?

You can upload MP3, WAV, FLAC, M4A, AAC, OGG, AIFF, WMA, Opus, AMR, APE, WavPack (WV), and most other common audio formats for both files. You can also upload video files (MP4, MOV, MKV, AVI, WebM, FLV, WMV, MPG, 3GP, and more) — we'll automatically extract the audio track. Maximum file size is 100 MB each for audio, 1 GB each for video. Audio longer than about 10 minutes may not finish processing in time — for best results, keep uploads under 10 minutes.

What format is the output file?

The merged track is delivered as a high-quality MP3 file.

Will overlay mode make one track quieter than the other automatically?

Overlay mode applies a small automatic level reduction to both tracks together to prevent clipping when they're summed — it doesn't selectively lower just one track relative to the other. For a specific balance (e.g. quieter background music under a voice track), adjust each file's volume beforehand with our Volume Adjuster.

Free Audio Merger Online