Decode base64 audio
Streaming APIs and voice services sometimes return MP3 data as base64. base64app decodes, detects MPEG audio, plays a preview, and downloads the file.
How it works
- 1. Paste base64 MP3 data above.
- 2. Click Decode and use the audio preview.
- 3. Download the audio file.
Common errors
- Invalid characters — standard base64 only uses A–Z, a–z, 0–9, +, /, and = padding.
- Missing or wrong padding — length should be a multiple of 4; add = at the end if needed.
- Line breaks and spaces — email, Slack, and JSON often insert whitespace that must be stripped.
- data: URI prefix left on the string — remove data:<mime>;base64, before decoding.
- URL-safe alphabet — JWTs and some APIs use - and _ instead of + and /.
- Truncated payload — a copied string cut off mid-way cannot be fully recovered.
- ID3 tags — valid MP3 with tags still decode; corruption usually means truncated data.
Frequently asked questions
Does it support WAV too?
Yes. base64app detects WAV, MP3, and other audio formats from decoded bytes.
Can I play audio before download?
Yes. An inline audio preview is shown when supported.
Large audio strings?
Very large base64 may be slow in-browser due to memory limits.
Is audio uploaded?
No. Playback and decode are local.
Is my data uploaded when I decode?
No. All processing runs in your browser. Nothing is uploaded, stored, or logged.
Can base64app fix corrupted base64?
Yes. Auto-repair fixes whitespace, data URI prefixes, URL-safe characters, padding, and stray characters.