Merge Audio
Merge audio files into one — in any order, seamlessly or with a crossfade, in the format you choose
Click or drop two or more audio files hereChoose two or more audio files
About Merge Audio
With Merge Audio, you can join two or more audio files into one. Each file is decoded on its own and the samples are joined, so no gap or click is added at the joins. Set the order by dragging or with the arrows, and, if you want, add a crossfade of 0.1 to 10 seconds, equal power or linear, join by join, plus a fade-in at the start and a fade-out at the end. Output: 6 lossless formats (FLAC, WAV, AIFF, ALAC, CAF, W64) and 8 compressed ones (MP3, M4A, raw AAC, M4R, OGG Vorbis, Opus, WMA, AC3). The joining always happens in the page with ffmpeg.wasm; only the final Opus encoding uses our server.
How to merge audio files into one
- 1Add two or more audio files by clicking or dropping them on the upload area; you can add more later.
- 2Drag files up or down, or use the ↑ and ↓ arrows; they are merged from top to bottom.
- 3Under "Transitions", check "Crossfade between files", "Fade in at the start", or "Fade out at the end" if you want them, and set "Length (seconds)" and "Curve".
- 4Choose the "Output format" and, for a compressed one, the "Bitrate".
- 5Click "Merge audio files", then "Download" to save merged_audio in the chosen format.
Formats and limits
- Input formats
- MP3, WAV, M4A, AAC, FLAC, OGG, OGA, Opus, WMA, AC3, AIFF, AIF, AMR, MKA, WEBA, CAF, MP2, M4B, M4R, WV, AU
- Output formats
- Lossless: FLAC, WAV, AIFF, ALAC, CAF, W64. Compressed: MP3, M4A, AAC, M4R, OGG, Opus, WMA, AC3.
- Bitrate
- MP3, M4A, AAC, M4R, and OGG: 64 to 320 kbps. Opus: 64 to 256. WMA: 64 to 256 requested, shown with the rate really written. AC3: 192 to 640.
- Files
- Two or more, with no maximum count; all are held in browser memory, so together they can weigh up to 750 MB on a computer and 300 MB on a phone or tablet
- Usage limits
- Opus output: a set number of encodings per connection per hour and per day, and the joined FLAC sent to our server must stay under its maximum size and length.
Where your file is processed
Your files are decoded and joined by ffmpeg.wasm on this page, whatever the output. For Opus output, the joined audio is then rendered as FLAC and sent to our server for libopus encoding; the service erases that FLAC as soon as it is encoded and the Opus file once your browser has it, or after 15 minutes. Should a merge fail, we receive one report: its cleaned message, the tool, and your browser with its version.
Frequently asked questions
Does the merger keep my files' format?
Yes, by default, when they share one: lossless files stay in their lossless format (FLAC if they differ, WAV for 32-bit or floating-point audio), and all-MP3 or all-Opus sets stay MP3 or Opus; raw AAC becomes M4A. Any other mix defaults to MP3 at 320 kbps.
Can MP3 files be joined without re-encoding?
No, not without gaps. Our test of September 26, 2026, found that copying the data left 18 to 40 ms of silence at each MP3 join, 26 to 30 ms for AAC, and garbled sound after Opus joins, from each file's encoder delay. This tool decodes each file and encodes once; pick FLAC or WAV to add no further loss.
Is the result lossless when I merge FLAC or WAV files?
Yes, with a lossless output: every sample of your files is kept unchanged, at their bit depth. Files at different sample rates are first converted to the highest one, and FLAC or ALAC store 32-bit or floating-point audio at 24 bits; the page says when either happens. Compressed outputs may end a few milliseconds longer than the sum.
Does a crossfade make the merged file shorter?
Yes, with "Overlap (shorter result)": each crossfaded join shortens the result by the fade length, shown before you merge. "Fade out, then in (same length)" keeps the full length. You can uncheck the crossfade at any single join.
Is equal power better than linear?
Yes, for two unrelated sounds: in our test of September 26, 2026, on two independent pink noises, equal power kept the level steady (-0.01 dB halfway through) while linear dipped by about 3 dB. Linear stays available for two recordings of the same sound, which add up in phase.