Base64 Encode / Decode

Base64 Converter

Switch between Encode and Decode modes. Supports plain text, Unicode, and file input including images — with an inline image preview for Base64 image strings.

Base64 Output

Copy Download Use as Input

⚠ URL-safe mode active: + → - and / → _, padding = removed.

Image Preview

Data URI (ready to embed)

Copy Data URI

What is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using only 64 printable ASCII characters: A–Z, a–z, 0–9, +, and /, with = used for padding. It is used to safely transmit binary data — such as images, files, or cryptographic keys — through text-based channels like email (MIME), JSON APIs, HTML data URIs, and HTTP headers that may not handle raw binary safely.

How to Use the Base64 Encoder / Decoder

1. Encode text: Select Encode mode and Text input, type or paste your text, and click Encode.
2. Encode a file: Select Encode mode and File input, then drag and drop or browse for any file. The output includes both the raw Base64 and a ready-to-use Data URI for images.
3. Decode: Switch to Decode mode, paste a Base64 string, and click Decode. If the decoded output is an image data URI, a live image preview appears automatically.
4. Enable URL-safe Base64 to replace + with - and / with _ for use in URLs and filenames.
5. Enable Add line breaks to wrap the output at 76 characters per line (MIME standard).
6. Use Use as Input to swap the output back to the input and switch modes for round-trip testing.

Key Features

• Text and file encoding: Encode plain text, Unicode strings, or any uploaded file.
• Image preview: When decoding a Base64 image string, an inline image preview renders automatically.
• Data URI output: File encoding produces a ready-to-embed data: URI for use in HTML or CSS.
• URL-safe mode: Produces RFC 4648 URL-safe Base64 (base64url) for use in URLs and JWT tokens.
• MIME line wrapping: Adds line breaks every 76 characters per the MIME standard.
• Input validation: Checks whether a pasted string is valid Base64 before decoding.
• 100% browser-based: No data is uploaded to any server.

Common Use Cases

• Email attachments (MIME): Email protocols transmit binary attachments as Base64-encoded text within the message body.
• Data URIs: Embed small images, fonts, or files directly in HTML or CSS using data:image/png;base64,... to eliminate HTTP requests.
• API payloads: JSON does not support binary data — files and images must be Base64-encoded before inclusion in JSON request/response bodies.
• JWT tokens: The header and payload sections of JSON Web Tokens are Base64url-encoded strings.
• Cryptography: Public/private keys and certificates are typically stored and transmitted in Base64 PEM format.
• Basic authentication: HTTP Basic Auth encodes credentials as Base64(username:password) in the Authorization header.

URL-Safe Base64 (base64url)

Standard Base64 uses + and / characters which have special meaning in URLs. URL-safe Base64 (defined in RFC 4648) replaces + with - and / with _, and typically omits the = padding. This variant is used in JWT tokens, OAuth 2.0, and any context where the Base64 string appears in a URL query parameter or filename.