Does cutting an MP3 reduce audio quality?

No. Because this tool operates directly on raw MPEG frames without decoding to PCM or re-encoding, acoustic fidelity is 100% identical to the source file.

Can I join MP3 files with different sample rates?

No. Joining files with mismatched sampling rates (e.g. 44.1 kHz and 48 kHz) is blocked because hardware audio players cannot alter playback clock rates mid-file without errors.

What is the maximum file size supported?

Files up to 100 MB are supported. The parser processes frame buffers in streaming chunks to maintain responsive user interaction.

Are ID3 metadata tags preserved during cuts?

Yes. Standard ID3v2 tags at the beginning of the track and ID3v1 tags at the end are extracted and re-attached to the trimmed output file.

Are audio files sent to a remote server for processing?

No. All frame scanning, cutting, and bitstream stitching execute locally in your web browser under connect-src none Content Security Policies.

AudioMP3 toolkit

Cut, join and tag MP3s

Whole MPEG frames are copied from your file to the result, so nothing is decoded and nothing is re-encoded. A 320 kbps file stays 320 kbps, and the audio you get back is the audio you started with.

Runs in this tab

Your MP3 files

MP3 only · up to 100 MB each · choose several to join them

Choose an MP3

Your file stays on this device. The original is never changed.

About this MP3 toolkit

Open an MP3 file of up to 100 MB to cut audio intervals, merge multiple files, or inspect MPEG audio frame headers. Cuts are executed on MPEG frame boundaries without decoding to PCM or re-encoding to MP3, preserving 100% of original acoustic quality with zero compression generational loss.

This toolkit performs lossless manipulation of MPEG Layer III audio streams by working directly at the frame bitstream level. Conventional audio editors decode MP3s to raw PCM and re-compress them, introducing audible distortion, ringing artifacts, and high-frequency roll-off. This tool parses MPEG sync words (0xFFE), reads bitrates and sampling frequencies, and splices raw frame packets directly, retaining existing ID3 tags where intact.

Runs in this tab — no uploadFree, no account, no watermark

Step by step

1Load MP3 tracksSelect one or more MP3 audio files up to 100 MB. The frame scanner verifies MPEG audio synchronization headers across all tracks.
2Choose operation: Cut, Join, or InspectSelect Cut to set start and end timestamps, Join to concatenate tracks in ordered sequence, or Inspect to review frame counts, bitrates, and ID3 metadata.
3Process lossless frame bitstreamThe engine slices and joins raw MPEG frames without re-encoding. Audio data remains in its compressed representation throughout execution.
4Download lossless resultSave the edited MP3 directly to your computer. File sizes and duration stats are verified immediately on output.

Why lossless frame splicing prevents quality loss

MP3 is a lossy perceptual audio format. Every time an MP3 is decoded to raw audio and re-compressed by a standard editor, lossy psychoacoustic algorithms discard additional frequency content. By inspecting the bitstream and cutting strictly at MPEG frame headers (every 1152 samples for Layer III), our cutter extracts exact bitstream slices without modifying Huffman-coded frequency coefficients, ensuring identical audio fidelity.

Bitrate compatibility rules when joining MP3s

When joining multiple MP3 files, all tracks must share identical sample rates (such as 44,100 Hz or 48,000 Hz) and MPEG layer definitions. While variable bitrate (VBR) files with varying frame bitrates can be merged if sample rates match, combining files of different sampling rates is rejected because standard decoders cannot switch sample clocks mid-stream without crashing.

Technical frame analysis and header validation

Every MPEG frame begins with an 11-bit frame synchronization marker. The toolkit validates the MPEG audio version (MPEG-1, MPEG-2, or MPEG-2.5), layer specification, CRC protection bits, and padding flags. Frame sizes are dynamically computed from the bitrate and sampling frequency, ensuring that corrupted or truncated frames at file boundaries are cleanly omitted from the output.

Zero upload security guarantee

Every response from this site is served with a Content Security Policy whose connect-src directive is set to none. That is not a promise in marketing copy; it is an instruction to your browser, and the browser is the one enforcing it. While this page is open it cannot open a connection to anywhere — not to this site, not to anyone else — so there is no path by which your document could be uploaded, not by a bug, not by a future change, not by a script that should not be here. e2e/egress-proof.spec.ts asserts the served header and then tries to send data out by every route a page has and requires each attempt to be refused, and it runs on every build.

The second half of the guarantee is that the code has nowhere to send anything from. lib/tools/local-source-policy.test.ts reads every source file under lib/tools, workers, components and app on every test run and fails the build if any of them contains fetch, XMLHttpRequest, WebSocket, EventSource, sendBeacon or a peer connection, or even a remote address written down in a comment. A tool here cannot acquire an upload by accident, because the file that would have to contain one cannot be committed.

Client-side processing limits

Computations run directly on your own device using WebAssembly, Web Workers, and modern browser APIs including Web Crypto and TextDecoder. There are no server queues, no background telemetry, and no temporary cloud files created. Large operations remain responsive by offloading heavy parsing and conversion tasks to dedicated worker threads, ensuring the browser UI never freezes during intensive document and data processing tasks.

Questions people ask

Does cutting an MP3 reduce audio quality?: No. Because this tool operates directly on raw MPEG frames without decoding to PCM or re-encoding, acoustic fidelity is 100% identical to the source file.
Can I join MP3 files with different sample rates?: No. Joining files with mismatched sampling rates (e.g. 44.1 kHz and 48 kHz) is blocked because hardware audio players cannot alter playback clock rates mid-file without errors.
What is the maximum file size supported?: Files up to 100 MB are supported. The parser processes frame buffers in streaming chunks to maintain responsive user interaction.
Are ID3 metadata tags preserved during cuts?: Yes. Standard ID3v2 tags at the beginning of the track and ID3v1 tags at the end are extracted and re-attached to the trimmed output file.
Are audio files sent to a remote server for processing?: No. All frame scanning, cutting, and bitstream stitching execute locally in your web browser under connect-src none Content Security Policies.