Join audio by selecting 2–10 browser-decodable files, arranging them in the desired order, and downloading one PCM16 WAV with the tracks concatenated directly. The final sequence follows the visible list exactly, so file order determines how the tracks appear in the joined result.
The Audio Joiner handles file reading, decoding, previewing, joining, WAV encoding, and downloading in the current browser tab. The source files are not uploaded, and there is no server-side conversion step if a browser cannot decode one of them.
The important preparation is to make sure every selected file can be decoded and shares the same channel layout. File extensions alone do not guarantee compatibility, and passing the input-size limits does not guarantee that the decoded audio will fit within every processing limit.
Prepare files that can be decoded together
The picker recognizes common MP3, WAV, M4A, AAC, Ogg, WebM, and FLAC file names and MIME types. Recognition only identifies a likely input; it does not guarantee that every codec variant can be decoded by Safari, Chrome, Firefox, or another browser.
Decoding uses the Web Audio API, and its available codecs depend on the current browser and operating system. MDN’s decodeAudioData documentation describes the browser operation used to turn encoded audio into a decoded buffer. The Audio Joiner does not add another codec library or a server fallback, so a file that the browser cannot decode must be repaired or supplied in a browser-decodable form.
Damaged, encrypted, incomplete, mislabeled, or unsupported files produce a clear error. This is particularly important for containers that can contain several codec variants: a valid-looking M4A or WebM name may still use a coding profile that the selected browser cannot handle.
Meet every selection and decoded-audio limit
The encoded input limits and decoded-audio limits apply together. A selection must satisfy all of the following values before the tool can complete the join.
| Constraint | Verified limit | What it affects |
|---|---|---|
| Number of files | 2–10 | At least two files are required, and no more than ten can be included. |
| Size per encoded file | 25 MiB (26,214,400 bytes) or smaller | This limit applies to each selected source file. |
| Total encoded input | 100 MiB (104,857,600 bytes) or smaller | The combined size of the selected files cannot exceed this budget. |
| Total decoded duration | 30 minutes or less | The duration is measured across all decoded tracks in the selection. |
| Decoded channel count | Up to 8 channels, with the same count for every file | Mono and stereo tracks cannot be combined in one selection. |
| Decoded working sample rate | Up to 192 kHz | The browser’s shared working rate must remain within the supported limit. |
| Sample budget | 30 million samples across all channels | A high-rate or multichannel selection can reach this budget before the duration limit. |
Nothing is shortened, downmixed, downsampled, or omitted to make a selection fit. If a limit is exceeded, the selection is rejected with a specific message rather than producing a partial or altered result.
Join the files in the intended sequence
- Open the Audio Joiner and choose 2–10 browser-decodable files together in one selection. Confirm that the files satisfy the displayed per-file and total input limits.
- Wait for browser decoding to finish, then preview each decoded track. Check that every preview contains the intended recording and review the displayed sample rate.
- Use Move up or Move down until the list shows the exact sequence you want. Reordering changes the decoded tracks and visible list together and clears any older joined WAV, so the final result cannot silently retain a previous order.
- Select Join in this order. The tool concatenates the decoded channel samples directly in that sequence, without inserting silence, overlapping tracks, crossfading, normalizing, adding a transition, or trimming automatically.
- Preview the resulting PCM16 WAV, paying particular attention to every join point and checking the channel playback when the tracks are stereo. Then download the file.
- Keep the source files until you have confirmed the downloaded duration, sequence, joins, channel playback, and file size. Do not delete an original based only on the length of the joined preview.
Match channels and the working sample rate
Every track in one selection must decode to the same channel count. A selection containing one mono file and one stereo file is rejected instead of silently duplicating, dropping, averaging, or remapping channels. For a focused explanation of that distinction, see Can I Mix Mono and Stereo Files When I Join Audio?.
All selected files are decoded through the same AudioContext. The browser may resample source material to that context’s working sample rate, which means the rate shown for the decoded tracks and result can differ from the rate stored in an original file. The output has one decoded working rate and does not preserve independent source sample rates.
Matching channels retain their decoded order. The channels are concatenated independently before they are interleaved into the WAV, so a left channel remains a left channel and a right channel remains a right channel. Channel conversion is therefore not part of the join; a mismatch must be resolved before the files can be processed together.
Understand the new PCM16 WAV
The download is a newly encoded RIFF/WAVE file containing interleaved, little-endian, signed 16-bit PCM samples. It is a new static representation of the browser-decoded audio, not a container-preserving copy of the inputs.
The original codec, bitrate, encoder settings, tags, album art, chapters, cue points, loop points, loudness fields, timestamps, and other container metadata are not retained. PCM16 WAV is uncompressed, so the joined file can be much larger than compressed MP3, AAC, Opus, Vorbis, or FLAC inputs. Keeping the sources until the download has been checked protects against losing details that the WAV does not preserve.
At each join, the last sample frame of one decoded track is followed immediately by the first sample frame of the next in the output channel arrays. Any silence already present inside a source recording remains part of that recording; the tool does not add a new pause between tracks.
Choose a different workflow for edits outside joining
The Audio Joiner is designed for combining complete, browser-decodable tracks in a direct sequence. Use Audio Cutter when you need a time range rather than a full track.
Use a dedicated editor when the task requires fades, loudness matching, channel conversion, compressed output, metadata preservation, or sample-level repair. Those operations are outside the joiner’s verified workflow and should not be assumed from the fact that the sources can be combined.
Save the result before temporary links expire
Selected files and the finished WAV use temporary local object URLs for playback and download. Those links are released when the selection is replaced or the page closes, so download the joined WAV before replacing it or leaving the tab.
Choosing the same files again is supported because the file input resets after every choice. This makes it possible to correct the sequence or selection without changing the source files on your device.