Base64 Decoder
Decode Base64 strings back into readable text instantly — free, unlimited, in your browser.
- Client-side processing
- Privacy-first
- Unlimited usage
- No account required
- Secure by design
Try a sample:
Input
Decoded Output
Frequently asked questions
- Is my data uploaded anywhere?
- No. Decoding happens entirely in your browser — nothing you paste is sent to a server.
- Why do I see "This doesn't look like valid Base64"?
- The string contains characters outside the Base64 alphabet (A–Z, a–z, 0–9, +, /, =) — check for stray text or extra symbols.
- Why do I see "This Base64 string is malformed"?
- Base64 text must be a multiple of 4 characters (with correct padding). This usually means the string was cut off or had characters removed.
- Why do I see "decodes to binary data that can't be displayed as text"?
- The Base64 is valid, but the bytes it decodes to aren't valid UTF-8 text — it's likely an image, file, or other binary data rather than text.
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What is the Base64 Decoder?
The Base64 Decoder recovers the original text from a Base64-encoded string — the reverse of Base64 encoding. Paste a Base64 string copied from an API response, a JWT segment, an email header, or a config file, and decode it back into readable text entirely in your browser.
Use cases
- Decoding a JWT header or payload segment to inspect its claims
- Recovering the original value from a Basic Auth header
- Decoding a Base64-encoded config value or environment variable
- Reading Base64-encoded content copied from an email header or API response
How to use the Base64 Decoder
- 1
Paste the Base64 string
Paste a Base64-encoded string into the input panel — whitespace and line breaks are fine.
- 2
Decode
Click Decode Base64 (or press Ctrl/Cmd+Enter) to recover the original text.
- 3
Copy or download
Use Copy to grab the result, or Download to save it as a text file.