Base64 Encoder / Decoder

What Is Base64 and Why Does It Exist?

Base64 is a way to encode binary data (images, files, any sequence of bytes) into a string of plain text characters. It was invented to solve a specific problem: early email systems and many text-based protocols could only transmit ASCII text, not raw binary data. Base64 converts any binary file into a set of 64 safe characters (A–Z, a–z, 0–9, +, /) that any system can handle without corruption.

Common Uses for Developers

• Inline images in HTML/CSS: Instead of referencing an external image file, small images (logos, icons) can be embedded directly in HTML or CSS as data:image/png;base64,.... This reduces HTTP requests but increases file size by about 33%.
• JWT tokens: JSON Web Tokens (used in API authentication) encode the header and payload in Base64URL (a slight variant of Base64). Paste a JWT into a Base64 decoder to read the claims inside it.
• API authentication: HTTP Basic Authentication encodes credentials as Base64(username:password) in the Authorization header. This is encoding, not encryption — Base64 provides zero security on its own.
• Storing binary in text fields: Databases that only support text storage can store images or files as Base64-encoded strings in VARCHAR or TEXT columns.
• Email attachments (MIME): Email attachments are Base64-encoded in the MIME message body — this is what those long blocks of text you see when viewing raw email source actually are.

Base64 Is Not Encryption

A common misconception: Base64 is purely encoding, not encryption. It is trivially reversible — anyone can decode a Base64 string in seconds. Never use Base64 to "hide" sensitive data. Encrypt data with AES or similar before encoding if security is required.

Base64URL Variant

Standard Base64 uses + and / which have special meanings in URLs. Base64URL replaces these with - and _ for safe use in URLs and filenames. JWT tokens use Base64URL. Our tool handles both variants.