Audio Joiner
Merge files in order, with optional normalization, crossfades, and gaps
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Your file is decoded, processed, and re-encoded in this browser tab. Nothing is uploaded to an OfflineTTS processing API.
Interactive Workspace
Audio Joiner
Combine several audio files into one. Add the files, arrange them in the order you want, and render a single output. The joiner handles the two problems that make naive concatenation sound bad: mismatched levels and abrupt seams.
Normalize each file: different recordings rarely sit at the same level. With this option on, each file is peak-normalized to -1.5 dBFS before joining, so a quiet phone recording does not disappear next to a mastered track. Turn it off when the files are already level-matched and you want the original dynamics preserved.
Crossfade: at 0 s, files are spliced end to end. Anything above that overlaps the end of one file with the start of the next, fading each into the other. A crossfade of one to three seconds works well for music; speech usually works better with a short gap instead, because a crossfade between two unrelated voices sounds like a mistake.
Gap between files: inserts deliberate silence, which is what you want for a podcast made of segments, an audiobook chapter list, or a set of announcements.
Order matters: use the up and down controls to arrange the sequence before rendering.
Export: WAV for a lossless merge, MP3 for sharing. Decoding, processing, and encoding all run in this browser tab. The file you select is not uploaded, and the rendered audio is not stored on any server.
How It Works
Add files
Select two or more audio files, or the audio track of video files.
Arrange the order
Use the up and down buttons to set the sequence.
Set level and seam
Choose per-file normalization, then a crossfade or a gap.
Merge and export
Render the combined file and download it as WAV or MP3.
Features
Unlimited Files
Add as many files as you need and arrange them in order.
Per-file Normalize
Brings mismatched recordings to a consistent peak level.
Crossfade or Gap
Overlap clips smoothly, or separate them with deliberate silence.
Reorderable
Move any file up or down in the sequence before rendering.
Level Matching Is What Makes a Merge Sound Right
Two files spliced together at different levels sound like two files spliced together. The ear notices the level jump immediately, and it reads as an edit rather than as one continuous piece. Peak normalization fixes the gross mismatch by bringing every file to the same maximum level.
Peak normalization is not the same as loudness matching. A file with a wide dynamic range and a single loud transient normalizes to a lower average level than a densely compressed file, even though their peaks match. If the pieces still sound uneven after normalizing, the compressed one needs to come down rather than the dynamic one going up — a limiter is a better tool for that than a normalizer.
Seams, Silence, and Export
The seam between two clips is where a merge succeeds or fails. Music benefits from a crossfade because the listener's attention follows the fade rather than the cut. Speech benefits from a short gap because silence is what a listener expects between two speakers or two segments — a crossfade in the middle of a sentence sounds like a glitch.
Every effect here is deterministic: the same file and the same control values produce the same output. That means you can reproduce a result later, but it also means the tool will not guess what you intended — check a short excerpt before rendering a long file, and keep the original.
WAV export writes every channel at the source resolution and keeps the merge lossless. MP3 export re-encodes the combined result, which is convenient for delivery but adds a generation of compression. If the merged file will become the input to another editing step, export WAV.
Related Tools
Volume Booster
Make a quiet recording louder and normalise inconsistent levels
Reverse Audio
Flip a recording backwards, with an optional pre-reverse reverb swell
Audio Trimmer
Drag a selection on the waveform, add fades, and export just that part
Audio Converter
Change sample rate and channel count, normalize, and re-export
Audio Joiner — FAQ
Can I join files in different formats?
Yes. Every file is decoded to PCM first, so MP3, WAV, FLAC, OGG, M4A, and video audio tracks can all be combined in one render. The output format is chosen separately at export.
What happens if the files have different sample rates?
They are all resampled to the sample rate of the first file in the sequence, so the merge stays consistent. Put the highest-quality file first if you want that rate to be the output rate.
Should I use a crossfade or a gap?
Crossfade for music where the pieces should flow into each other. Gap for speech, where overlapping two different voices sounds like an editing error. Start with a one-second crossfade for music and a half-second gap for spoken segments.
Why does my joined file sound quieter than the originals?
If per-file normalization is on, each file is scaled to -1.5 dBFS, which may reduce a file that was already louder than that. Turn normalization off to preserve the original levels, and use the volume booster afterwards if the merged result needs a lift.
Is there a file size limit?
There is no fixed limit, but everything is held in memory. Very long files use a lot of RAM, so merge in batches for hour-long content.
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