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CrateX.app

Compress Audio

Reduce one audio file locally in your browser and export a CBR MP3. Choose a standard bitrate or aim for a target size, with automatic or mono channel output.

Processing stays in this browser. CrateX.app does not upload your source audio.
Compress Audio

Quick Start

1
Choose one audio file
2
Choose a bitrate or target size and channel mode
3
Compress it while keeping this tab open
4
Preview and download the MP3

Common Scenarios

Sharing

make a recording smaller for chat, email, or an upload limit.

Storage

reduce space used by voice notes, music drafts, or archived recordings.

Playback

create an MP3 for apps and devices that accept this common format.

Input & Output

Input: one local audio file with a primary track that your browser can decode.
Modes: choose a fixed 48–320 kbps bitrate or a 0.1–500 MB target. Target-size planning is best effort.
Channels: Auto keeps mono sources mono and makes other inputs stereo; Mono mixes every source down to one channel.
Output: one CBR MP3. The sample rate is adjusted to the nearest MP3-compatible rate, and bitrates above 160 kbps use 32, 44.1, or 48 kHz.
The result is limited to 512 MiB. Metadata, cover artwork, and additional tracks are not copied.

Usage Advice

For speech, a lower bitrate or mono may be enough. Music with more detail usually benefits from a higher bitrate and stereo.
Target-size mode reserves encoding overhead and selects the highest standard bitrate within the estimate. If the first MP3 is too large, the tool retries once at the next lower bitrate.
Keep the tab open and your device awake. Long recordings can take time and use substantial memory.
Keep the original when quality matters or when the compressed MP3 is not smaller.

Limitations & Compatibility

MP3 compression is lossy and cannot improve or restore source quality.
Input support depends on the formats and codecs your browser can decode; a familiar extension does not guarantee support in every browser.
Target sizes are estimates, not exact promises. The final MP3 may be smaller or larger, and only one automatic lower-bitrate retry is available.
The supported CBR bitrate range is 48–320 kbps. Targets that require less than 48 kbps are marked unreachable.
Auto preserves mono only; every non-mono source becomes stereo. Mono explicitly mixes the source to one channel.
Metadata, tags, chapters, cover artwork, and additional audio tracks are not preserved.
This tool processes one file at a time and does not provide batch compression.
A result larger than 512 MiB cannot be returned by this tool.

Privacy & Security

CrateX.app reads and compresses the selected audio locally in your browser and does not upload it. The source and generated MP3 remain in page memory while the tool is open. Download or locally share the result yourself, and clear the page, downloads, and site data on shared devices when needed.

FAQ

6

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All tool processing happens locally in your browser.