Base64 Encoder & Decoder
Encode text to Base64 or decode Base64 back to text, with full UTF-8 and URL-safe support. Runs entirely in your browser — nothing is uploaded.
Base64
SGVsbG8sIFNjb3V0TXlUb29sISDwn5ug77iP
About this tool
Base64 encodes arbitrary bytes as a 64-character alphabet (A–Z, a–z, 0–9, + and /) so binary or non-ASCII data can travel safely through text-only channels like JSON, URLs, email headers, and data URIs. This tool encodes any text — including emoji and other Unicode — by first converting it to UTF-8 bytes, so multi-byte characters round-trip correctly, which the naive browser btoa() function cannot do on its own. Decoding reverses the process and validates that the result is well-formed UTF-8, surfacing an error rather than silently producing garbage. A URL-safe option swaps + and / for - and _ and drops the trailing = padding, matching the base64url variant used in JWTs and many web APIs. Everything happens locally in your browser; the text you paste is never sent anywhere.
How to use it
- Choose Encode or Decode.
- For encoding, optionally tick URL-safe to get the base64url variant.
- Paste or type your input.
- Copy the result from the output panel.
Frequently asked questions
- Does this handle emoji and non-English text?
- Yes. Text is encoded to UTF-8 bytes before Base64 and decoded back the same way, so emoji, accented characters, and any Unicode round-trip exactly. The plain browser btoa() function breaks on such characters; this tool does not.
- What is "URL-safe" Base64?
- It is the base64url variant from RFC 4648: the + and / characters are replaced with - and _, and the = padding is removed. This makes the string safe to drop into a URL or filename without escaping. It is the encoding used by JWT tokens.
- Why do I get an error when decoding?
- Either the input is not valid Base64 (wrong characters or length), or the decoded bytes are not valid UTF-8 text. The tool decodes URL-safe input automatically and re-adds missing padding, so the most common cause is a stray or truncated string.
- Is Base64 a form of encryption?
- No. Base64 is an encoding, not encryption — anyone can decode it. It only changes the representation of data so it survives text channels; it provides no confidentiality. Never use it to "hide" secrets.
- How much larger does Base64 make my data?
- About 33% larger: every 3 bytes of input become 4 Base64 characters. That overhead is the price of representing binary data in a restricted text alphabet.
- Is my input uploaded anywhere?
- No. Encoding and decoding run entirely in your browser with no network calls, so even sensitive text or tokens stay on your machine.