One decoder for every file type
Not sure what your base64 contains? base64app inspects decoded bytes and picks the correct MIME type and extension — PDF, images, archives, audio, video, JSON, or binary.
How it works
- 1. Paste any base64 string into the decoder above.
- 2. Click Decode and review the detected file type.
- 3. Preview when possible and download with the right extension.
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.
Frequently asked questions
What file types are supported?
PDF, images, JSON/text, ZIP, Office docs, audio, video, fonts, and generic binary.
How is the file type chosen?
Magic-byte detection on decoded bytes — not just the data URI prefix.
Can I decode unknown binary?
Yes. Unknown types download as .bin with a binary label.
Corrupted base64?
Enable auto-repair for best results.
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.
Is base64app free?
Yes — free with no sign-up required.