Castos
Free Podcast Tool

Trim Audio Online

Cut the beginning and end of an audio file with waveform precision. Free, private, and entirely in your browser.

Your audio stays on your device. Nothing is uploaded or stored.

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How To Trim An Audio File

  1. Step 1

    Choose Your Audio

    Select an MP3, WAV, M4A, AAC, OGG, or FLAC file from your device. The recording stays in your browser and is never uploaded.

  2. Step 2

    Select What To Keep

    Move the start and end handles around one continuous section. Preview the selection or use Find Silent Edges to remove quiet audio at either end.

  3. Step 3

    Trim And Download

    Click Trim Audio and download a podcast-ready MP3. The export is fixed at 128 kbps for clear spoken audio and a practical file size.

Cut The Beginning And End With Precision

Recordings often start with setup chatter, a few seconds of room tone, or an awkward pause. They may also continue after the conversation is over. The waveform gives you a visual map of the file so you can place each cut precisely, preview the result, and keep only the continuous section you need.

Silent Edges, Not Missing Pauses

Find Silent Edges looks only for quiet audio at the beginning and end of the recording. It does not delete pauses inside the episode. Those pauses may be part of the speaker's timing, so removing them automatically could change the conversation in ways you did not intend.

Podcast-Ready MP3 At 128 kbps

Every trimmed file is exported as an MP3 at 128 kbps. This is a standard podcast setting that keeps voices clear while controlling file size. There is no format menu to configure and no extra setting to second-guess.

Audio Ready? Publish Your Podcast In 3 Steps

  1. Upload a new episode in Castos

    Upload The MP3

    Create a show in Castos and upload the trimmed MP3 with your episode title, description, and artwork.

  2. Fill in podcast details in Castos

    Get Your Feed And Website

    Castos creates the RSS feed podcast apps need and a customizable site where listeners can find every episode.

  3. Link your feed to each podcast directory

    Publish Everywhere

    Submit your feed to Apple Podcasts, Spotify, and other directories once. Future episodes are distributed automatically.

Frequently Asked Questions

How do I trim an audio file online?
Choose an audio file above, move the start and end handles around the section you want to keep, and preview the selection. Click Trim Audio when it sounds right, then download the finished MP3.
Does the audio trimmer remove every silent gap?
No. The trimmer keeps one continuous section and removes only the audio before and after it. Find Silent Edges can suggest cuts for quiet audio at the beginning and end, but it does not remove pauses inside the recording.
What format and bitrate does the trimmer export?
The tool exports MP3 files at 128 kbps. This is a standard podcast bitrate that keeps spoken audio clear while producing a practical file size for hosting, downloading, and listening.
Is my audio uploaded or stored anywhere?
No. Your browser processes the audio on your device with WebAssembly. Castos never receives or stores the source file or trimmed MP3. Close the tab and the working files disappear.
Which audio formats can I trim?
The tool accepts MP3, WAV, M4A, AAC, OGG, and FLAC files up to 500 MB. Browser codec support can vary, so converting an unusual file to MP3 or WAV is the best fallback.

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Publish Your Trimmed Audio With Castos

Upload your MP3, create your podcast feed, and distribute every episode from one place.

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