Online Base64 Encoder & Decoder
/convert/UTF-8 & RFC 4648 Compliant · 100% Client-Side In-Browser
What is Base64 Encoding and How Does It Function?
Base64 is a binary-to-text encoding scheme designed to represent binary data in an ASCII string format. The encoding divides every 3 bytes (24 bits) of raw binary data into 4 groups of 6 bits each. Each 6-bit chunk maps directly to one of 64 printable characters in the standard Base64 index table: uppercase letters A-Z, lowercase letters a-z, numerals 0-9, and symbols + and /.
When data length is not evenly divisible by 3, padding characters (=) are appended to the end of the string to ensure the resulting text is a clean multiple of 4 characters. In web development, Base64 is essential for embedding small inline images directly into CSS stylesheets or HTML as data:image/png;base64,... data URIs, encoding HTTP Basic Authentication credentials, and transporting cryptographic hashes across email networks.
Standard Base64 contains characters like +, /, and = which have reserved meanings in URL query strings. LocalDevTools includes an optional URL-Safe Base64 mode (RFC 4648 §5) which swaps + for -, / for _, and omits trailing padding, making strings safe for web query parameters and JWT tokens.
How to Encode or Decode Base64 Strings
- Select your conversion mode: Choose Text → Base64 (Encode) to convert human text into Base64, or Base64 → Text (Decode) to unpack a Base64 string.
- Configure URL-Safety: When encoding parameters for web URLs or API endpoints, toggle the URL-Safe Base64 (RFC 4648) checkbox.
- Input your data: Paste your content into the left editor pane. The tool converts in real-time as you type.
- Export output: Click Copy Output to transfer the result immediately to your clipboard.
Frequently Asked Questions (FAQ)
Is Base64 an encryption algorithm? ↓
No. Base64 is an encoding format, not encryption. Anyone can decode a Base64 string instantly without a secret key. Never use Base64 alone to protect passwords or confidential data without cryptographic encryption (such as AES-GCM).
Why does Base64 increase data size by ~33%? ↓
Because 3 bytes (24 bits) of raw binary data are represented using 4 ASCII characters (32 bits), Base64 encoding inherently expands data size by roughly 33.3%. This is a natural tradeoff for allowing binary data to travel safely across text-only protocols like SMTP and HTTP.
Does this tool support international characters and emojis? ↓
Yes! While native JavaScript btoa() throws an exception when encountering multi-byte characters, LocalDevTools uses native TextEncoder and TextDecoder to safely handle all UTF-8 characters, Asian scripts, and modern emojis without character corruption.