Security & Encoding

Base64 Encoder / Decoder

Encode text to Base64 or Base64URL, or decode them back to text. UTF-8 safe using TextEncoder/TextDecoder. Runs entirely in your browser.

● LOCAL ● NO NETWORK ● RFC 4648
⚠ Base64 is encoding, not encryption. Anyone who sees the encoded string can decode it instantly. Never use Base64 to conceal passwords, API keys, or other sensitive data.

Related tools

JWT Decoder URL Encoder / Parser Hash Generator
JWT & Encoding: Working with tokens? The JWT Decoder automatically handles Base64URL decoding for headers and claims. To calculate cryptographic digests of base64-encoded strings, use the Hash Generator.

About Base64 & Base64URL

What it does

Base64 encodes binary data as printable ASCII characters using a 64-character alphabet (A–Z, a–z, 0–9, +, /). This tool encodes UTF-8 text to Base64 or decodes Base64 back to text. Base64URL is a URL-safe variant that replaces + with - and / with _, and omits padding — it is used in JWTs, URL parameters, and file names.

How it works

Text is encoded to UTF-8 bytes using the browser's TextEncoder API, then to Base64 using btoa(). Decoding uses atob() then TextDecoder to recover the original UTF-8 text. This replaces the deprecated escape()/unescape() pattern previously used.

No data leaves your browser. Input text may be saved locally in your browser's localStorage.
EngineTextEncoder / TextDecoder + Uint8Array
UTF-8 supportFull multi-byte Unicode safe
Network transferNone

Common mistakes

  • Base64 is not encryption: Anyone can decode a Base64 string instantly. Never use Base64 to conceal passwords, API keys, or sensitive data.
  • Standard vs URL-safe: JWT segments use Base64URL (no padding, different characters). Pasting a JWT segment into a standard Base64 decoder requires converting - back to + and _ back to /.