MP3 test-file generator
Build a valid, playable MP3 of any size — up to 2 GB — right in your browser. Pick the MPEG version, the sample rate, a target size and the ID3 tags — or hit Smallest possible for a one-frame file; the file is silent (real MPEG Layer III frames, zero audio) and streams straight to a file you choose. Nothing is uploaded. Drop the result back onto the MP3 viewer to inspect it.
What you get
A byte-for-byte valid MP3: an ID3v2.4 tag block with your metadata, followed by a run of MPEG Layer III frames whose audio content is digital silence (a correct 4-byte sync header plus zeroed side-info and main-data). Every mainstream player and the OmniViewer MP3 viewer read it as a normal file — the ID3 tags, the frame count, the reported duration and bitrate are all real.
| Version | Sample rate | Samples / frame | Frame length | Sync bytes |
|---|---|---|---|---|
| MPEG-1 Layer III | 44.1 kHz | 1152 | 417 B @ 128 kbps | FF FB |
| MPEG-2 Layer III | 22.05 kHz | 576 | 208 B @ 64 kbps | FF F3 |
| MPEG-2.5 Layer III | 11.025 kHz | 576 | 208 B @ 32 kbps | FF E3 |
Want to understand every field? Read the anatomy of an MP3 file.
How it works
Where the browser supports the File System Access API (showSaveFilePicker — Chrome, Edge, Opera), the tag and frames stream to your chosen file ~1 MB at a time in a background worker; there is no in-memory buffer of the whole file, so a 2 GB file costs the same memory as a 2 KB one. On Firefox and Safari it falls back to assembling a Blob in memory and downloading it — fine for modest sizes, but large files may run into the browser's memory limits.