Free Base64 Encoder & Decoder that works offline
Use this free Base64 encoder and decoder to convert ordinary Unicode text into Base64 or turn a Base64 string back into readable UTF-8. Conversion happens entirely on your device. Results can optionally be saved to a 50-item local history, protected with a master password and backed up as JSON.
What this base64 encoder & decoder does
Base64 represents binary bytes with a limited set of printable ASCII characters. It is useful when a text-only format needs to carry data, but it is encoding rather than encryption. This tool uses the browser’s UTF-8 encoder before creating Base64, which means names, emoji and non-English characters are handled correctly. Optional history encryption derives an AES-GCM key from your password with PBKDF2, and remains compatible with history created by the original Base64 PWA.
How to use the Base64 Encoder & Decoder
- Paste plain text and choose Encode to Base64, or paste Base64 and choose Decode.
- Review the result and use the copy button when it is correct.
- Add an optional description and save useful conversions to local history.
- Enable history encryption for local protection, or export and import a readable JSON backup.
Common uses
- Preparing small values for JSON, XML or text-based API payloads
- Inspecting encoded configuration, email or data URL content
- Testing application integrations without sending sample data to a third party
- Teaching the difference between data encoding, hashing and encryption
Private processing and offline access
This tool does not submit your input to a conversion server. Processing takes place inside the browser using local JavaScript and standard Web APIs. After the PWA has been installed or cached, the page and its core features remain available without an internet connection. Closing or clearing the page removes unsaved input; the tool does not create an account or cloud history.
Tips for accurate results
- Do not treat Base64 as a security control; anyone can decode it.
- Keep the encryption master password safe: encrypted history cannot be recovered without it.
- For JWT segments, use the dedicated JWT decoder because tokens normally use Base64URL rather than standard Base64.
Frequently asked questions
Is Base64 encryption?
No. Base64 is a reversible encoding. It does not use a secret key and it does not protect sensitive data.
Can this tool encode emoji and accented characters?
Yes. Input is converted to UTF-8 bytes before Base64 encoding, so modern Unicode text is supported.
Where is Base64 history stored?
Saved history stays in local browser storage. It can optionally be protected with AES-GCM encryption and exported as JSON.
Does my Base64 data leave the browser?
No. Encoding, decoding, local history encryption and copying happen on your device.