Decode base64 ZIP archives
ZIP files sent through APIs or email are often base64-encoded. base64app detects the PK zip signature after decode and offers a .zip download.
How it works
- 1. Paste base64 ZIP data above.
- 2. Click Decode.
- 3. Download the .zip archive.
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.
- gzip vs zip — gzip streams are not ZIP; detection distinguishes archive types.
Frequently asked questions
Can I decode base64 to ZIP?
Yes. When bytes start with a ZIP signature, base64app offers a .zip download.
Can I open the ZIP here?
base64app downloads the archive. Open it with your OS zip tool.
What about DOCX/XLSX?
Office files are ZIP-based; they may detect as ZIP or Office depending on content.
Is the archive uploaded?
No. Decoding is client-side.
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.