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Audio Joiner Online

This free audio joiner online merges two or more MP3 and WAV files into one audio file, right in your browser. Upload your clips, drag them into the right order, check the total length, and download the joined result as a WAV or an MP3 — your audio never leaves your device, because the whole job happens on your own computer.

How it works

Joining audio sounds simple — play one clip, then the next — but files do not line up that easily on their own. An MP3 stores sound in compressed frames, a WAV stores raw samples, and two files can have different sample rates, different channel counts, and different lengths. This joiner handles all of that in your browser: it decodes every file you add into raw sound samples, converts them to one shared sample rate and channel layout, lines the samples up end to end, and writes the result out as a brand-new file. Nothing is uploaded, so the work is as fast as your computer allows and your recordings stay private.

Adding files is the first step. Click the drop zone or drop files onto it — MP3 and WAV files can be mixed freely, and you can add more files later without losing the ones already loaded. Each clip appears in a list with its name, its length, and its file size, and the total duration updates as you go. The up and down arrows move a clip one place earlier or later in the order, and the cross removes it. The order in the list is the order in the final track, so put the intro first and the outro last before you press Join.

The output settings control the format of the joined file. Output sample rate sets how many samples each second of the result holds. The default, "First file's rate", keeps the sample rate of the first clip and resamples the others to match, which is the right choice when the clips came from the same recording session. You can also force 44,100 Hz for CD-quality output, 22,050 Hz for voice, or 16,000 Hz for speech tools. Channels works the same way: keep the first file's layout, force mono by mixing both channels into one, or force stereo by duplicating a mono clip onto both channels. When a clip is resampled, the samples are re-spaced with linear interpolation, which keeps the pitch and timing correct.

Pressing Join audio builds the joined track and shows its total duration, sample rate, channels, and the sizes of both exports. The Download .wav button saves an uncompressed 16-bit WAV file — the exact joined samples, with nothing thrown away. The Download .mp3 button encodes the same joined audio as an MP3 at the bitrate you picked: 128 kbps for speech, 192 kbps for a good balance of music quality and size, and 320 kbps for the best quality. A WAV of one minute of stereo audio at 44,100 Hz is about 10 MB; the same minute as a 192 kbps MP3 is about 1.4 MB, so pick WAV when you plan to edit the result further and MP3 when you want a small file to share or upload.

Two practical points are worth knowing. First, joining itself does not change the sound quality — the samples are copied end to end without any processing, so a joined WAV sounds exactly like the original clips played in sequence. The only quality change comes from choosing MP3 export, which compresses the result a second time. Second, very long projects use a lot of memory, because the audio is held uncompressed while you work. Joining a dozen clips totalling under an hour is comfortable on most computers; if the browser slows down, split the job into two smaller joins and combine the results.

Worked example

A teacher records a short lesson in three voice memos on her phone: an intro, the main lesson, and a closing summary. She exports them as intro.mp3 (0:45, 0.7 MB), lesson.mp3 (3:20, 3.1 MB), and closing.mp3 (0:55, 0.9 MB), all mono, 44,100 Hz.

Step 1: Drop all three files onto the joiner. The list shows each clip with its length, and the total reads 5:00 — 45 + 200 + 55 seconds.
Step 2: The order is already intro, lesson, closing. If it were not, the up and down arrows would fix it.
Step 3: Keep First file's rate (44,100 Hz) and Keep first file's channels (mono), then press Join audio.

The tool builds one 5-minute mono track at 44,100 Hz. The joined WAV is 25.2 MB — 300 seconds × 44,100 samples per second × 1 channel × 2 bytes per sample, plus a 44-byte header — and the 128 kbps MP3 export is about 4.6 MB. She downloads the MP3 and uploads it to the class page, where it plays as a single lesson from start to finish.

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