Merge audio files into one MP3
To merge audio files, drop them here, put them in order and press Merge: this free tool joins up to 20 recordings into one MP3 right in your browser. It evens out the volume between files, adds a short pause if you want one, and reads MP3, M4A, WAV, OGG, OPUS and AMR. No signup, nothing is uploaded.
- Total length
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- MP3 size
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- To transcribe
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Nothing is uploaded. The files are merged in this tab and gone when you close it.
How merging works, and when to skip it
Recordings rarely come in one piece. A recorder splits a long session into parts, a chat holds a stack of voice messages, a lecture ends up as three files. This page decodes each file with your browser's own audio engine, brings them all to one sample rate, evens out the volume if you ask it to, and writes a single MP3 on your device. Formats a browser cannot read, such as AMR and 3GP, go through ffmpeg compiled to run in the page.
File names from WhatsApp and from voice recorders carry the date, so Sort by name usually gives the right order. If you are merging only to get one transcript, you can skip this step: Speecho transcribes the files separately and merges the transcripts into one text.
Questions
How do I put the files in the right order?
Use the arrows next to each file, or drag a row with the mouse. Sort by name does it in one click when the names carry a date or a number, as WhatsApp voice messages and recorder files do. The merged MP3 follows the list from top to bottom.
Which audio formats can I merge?
MP3, M4A, AAC, WAV, FLAC, OGG, OPUS and WEBM are decoded by the browser itself, and you can mix formats in one merge. AMR and 3GP from old phones, and Opus in a browser that cannot decode it, go through a decoder (ffmpeg, about 30 MB) that the page downloads the first time it is needed. The result is always one MP3.
Do my files leave my device?
No. Decoding, merging and MP3 encoding all run in this browser tab. You can check the network tab of your browser: the files are never sent anywhere.
How many files and how much audio can I merge?
Up to 20 files, each up to 2 hours long, 5 hours in total. The files are processed one at a time, so a long merge never holds all the audio in memory at once. Very long recordings are still easier on a computer than on a phone.
What does "Even out the volume" do?
Voice messages from different people and devices are recorded at different levels, so a merged file jumps between quiet and loud. With the option on, the tool measures the speech level of each file and applies one gain per file to bring them to a common level, limited so that the loudest peak does not clip. It changes nothing inside a file. Turn it off to keep the original levels.
Do I need to merge the files before transcribing them?
No. In Speecho you can upload the files as they are, up to 5 per upload. Each one is transcribed, then you select 2 to 20 transcripts in your history and merge them into one, in the order you set. Merge the audio first only if you also want a single audio file.