Base64 Encoder & Decoder

Encode and decode Base64 strings with UTF-8 emoji support, standard vs URL-safe modes, MIME line wrapping, and data URL image preview.

Raw Text / File Input
Chars: 63Bytes: 65 B
Base64 Output
Valid Output
Chars: 88Bytes: 88 BRatio: 135%
100% Client-Side Privacy: No text, binary data, or credentials ever leave your browser.

How to use Base64 Encoder & Decoder

  1. 1Select your desired operation: 'Encode (Text → Base64)' or 'Decode (Base64 → Text)'.
  2. 2Paste your raw string, JWT payload, or credentials into the input editor, or click 'File' to load an image or text document.
  3. 3Choose formatting options: Standard (+/) vs. URL-Safe (-_), Strip Padding (=), or Wrap at 76 characters.
  4. 4Inspect the real-time output preview, byte size calculation, and data URL image preview (if decoding an image asset).
  5. 5Click 'Copy' to immediately copy the encoded or decoded string, or click 'Save' to download as a text file.

Key Features & Highlights

  • •RFC 4648 Standard & URL-Safe Encoding: Toggle instantly between standard RFC 4648 §4 (+ and /) and RFC 4648 §5 URL/filename safe (- and _) alphabets.
  • •100% Unicode & Emoji Preservation: Powered by TextEncoder and TextDecoder to eliminate the Latin-1 / UTF-8 character corruption errors common in legacy btoa/atob implementations.
  • •Data URL & Image Inspection: Automatically identifies image/png, image/jpeg, and image/svg+xml data URIs and renders an interactive visual preview.
  • •MIME Line Chunking: Optional 76-character line break insertion complying with email and MIME RFC 2045 specifications.
  • •Padding Management: One-click option to strip trailing '=' padding characters for compact query strings and JSON Web Token (JWT) formatting.
  • •Bi-Directional Instant Swap: Swap input and output with one click for continuous validation and testing workflows.
  • •Zero-Server Exposure: All encoding and decoding runs in-memory inside your browser; sensitive tokens, keys, and credentials are never transmitted.

Understanding Base64 Encoder & Decoder

Encode raw text, Unicode strings, and binary files into standard Base64 or URL-safe Base64, and decode Base64 strings back to clean plaintext or inspect data URLs. Compliant with RFC 4648 and RFC 2045 specifications, this tool provides full UTF-8 byte boundary safety, emoji preservation, optional MIME 76-character line wrapping, padding removal (=), live file uploads, and an embedded data URL image preview. All calculations occur strictly client-side within your browser sandbox.

Frequently Asked Questions

What is Base64 encoding and how does it work?

Base64 is a binary-to-text encoding scheme that translates arbitrary binary sequences or text octets into a set of 64 ASCII characters (A-Z, a-z, 0-9, +, /). Because 64 is 2^6, each Base64 character represents exactly 6 bits of data. Three 8-bit bytes (24 bits) are represented by four 6-bit Base64 digits, resulting in a predictable data expansion of approximately 33%.

What is the difference between standard Base64 and URL-safe Base64?

Standard Base64 (RFC 4648 §4) uses '+' and '/' characters, which have reserved syntactic meanings in URLs (like query string separators and path delimiters) and can cause file system errors. URL-safe Base64 (RFC 4648 §5) replaces '+' with '-' (hyphen) and '/' with '_' (underscore), and frequently strips the trailing '=' padding, allowing safe usage inside URLs, cookies, and JWT tokens.

Why do standard Javascript btoa() and atob() crash on emojis and international characters?

The browser's native btoa() function only supports 8-bit Latin-1 code points (0x00 to 0xFF). When passing UTF-8 multi-byte characters such as emojis or non-Latin alphabets, btoa() throws an 'InvalidCharacterError'. Our tool converts strings into UTF-8 byte arrays using modern TextEncoder and TextDecoder APIs, guaranteeing seamless encoding and decoding across all global languages and symbols.

Is Base64 encoding the same as encryption?

No. Base64 is purely an encoding mechanism designed for data transport across protocols that only support ASCII text (such as email, HTTP headers, or HTML data URIs). It provides zero cryptographic security or confidentiality. Anyone can decode a Base64 string instantly without a key.

Why are '=' characters appended to the end of Base64 strings?

Base64 processes input in 3-byte chunks (24 bits). If the final chunk of your input data contains only 1 or 2 bytes, padding characters ('=') are added to fill the 4-character output block, signaling the decoder how many non-significant zero bits were added.

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