What Is Base64 Encoding?
Base64 encoding converts every 3 bytes of input data into 4 ASCII characters from a 64-character alphabet. This expansion (33% size increase) is the trade-off for ensuring the data can pass safely through text-based protocols that might corrupt raw binary data. The 64-character alphabet includes uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), and two additional characters (+ and /). Padding with = is added to make the output length a multiple of 4.
- Input is processed in 3-byte groups, each producing 4 Base64 characters
- Output size is approximately 133% of input size due to the encoding overhead
- The = padding character appears at the end when input length is not divisible by 3
- Base64 is an encoding, NOT encryption — it provides no security, only format conversion
- Standard Base64 uses A-Z, a-z, 0-9, +, and / (URL-safe variant uses - and _ instead of + and /)
Base64 is NOT encryption. Anyone can decode a Base64 string instantly. Do not use Base64 to "hide" sensitive data — it provides zero security. Use proper encryption (AES, RSA) for data protection.
Common Use Cases
Base64 encoding appears in many web development contexts where binary or special-character data needs to be transmitted through text-based channels.
- HTTP Basic Auth: Authorization: Basic base64("username:password")
- Data URIs: data:image/png;base64,iVBORw0KGgo... (embed images in HTML/CSS)
- Email (MIME): Binary attachments encoded for text-based email transport
- JSON payloads: Embedding binary data (images, files) in JSON API requests
- Cookies: Encoding complex values for safe storage in browser cookies
- JWT tokens: Header and payload sections use Base64URL encoding
How to Encode Text to Base64
Encoding is instant — type or paste your text and see the Base64 output immediately.
- Step 1: Type or paste your text into the input field
- Step 2: The Base64-encoded output appears instantly
- Step 3: Copy the encoded string to use in your application, API request, or configuration
For HTTP Basic Authentication, encode your credentials in the format "username:password" (with the colon). The result is placed in the Authorization header as: Authorization: Basic <encoded_string>.
Base64 vs. Base64URL
Standard Base64 uses + and / characters, which have special meaning in URLs. Base64URL is a variant that replaces + with - and / with _ to make the output safe for inclusion in URL parameters and filenames. JWT tokens use Base64URL encoding for this reason. Our tool uses standard Base64 encoding. If you need Base64URL, simply replace + with -, / with _, and remove trailing = padding from the output.
Encode Your Data Instantly and Privately
Base64 encoding is a fundamental tool for web developers, used in authentication, data embedding, and protocol compatibility. Our encoder converts text to Base64 instantly using your browser's native capabilities, with zero network requests and complete privacy. Try it now — paste any text and get the Base64 output in milliseconds.