Base64 Encoder & Decoder
Free Base64 encoder/decoder. Convert text and images to/from Base64. Fast, secure, client-side processing. No signup needed.
About This Tool
Base64 Encoder/Decoder converts text or binary data to and from Base64 encoding directly in your browser. It supports standard Base64 (RFC 4648) and URL-safe Base64 variants. Perfect for developers working with APIs, email attachments (MIME), data URIs, or JWT tokens.
How It Works
Base64 encoding converts binary data into a set of 64 printable ASCII characters (A-Z, a-z, 0-9, +, /), plus '=' for padding. The algorithm takes the input byte stream and processes it in 3-byte (24-bit) groups. Each 24-bit group is split into four 6-bit segments, and each segment maps to one of the 64 characters in the Base64 alphabet.
If the input length is not a multiple of 3, the encoder pads the final group with zero bits and appends one or two '=' characters to signal the padding. This ensures the encoded output length is always a multiple of 4 characters. Decoding reverses this process: each Base64 character is mapped back to its 6-bit value, the bits are concatenated, and the original byte stream is reconstructed. URL-safe Base64 replaces '+' with '-' and '/' with '_' to avoid conflicts in URLs and filenames.
How to Use
- 1Choose Text ↔ Base64 or Image ↔ Base64 tab.
- 2Text tab: Select encode/decode direction and enter your text or Base64 string.
- 3Image tab: Drag & drop an image, or paste a Base64 string to preview.
- 4Toggle URL-safe to get JWT-compatible or URL-parameter-safe Base64.
- 5Copy the result or swap input/output for reverse conversion.
Frequently Asked Questions
What is Base64 encoding?
Base64 is an encoding method that converts binary data into ASCII text. It transforms 3 bytes into 4 safe ASCII characters, making it suitable for email, URLs, JSON, and other text-based protocols.
What is URL-safe Base64?
URL-safe Base64 replaces + with - and / with _ from standard Base64. It also removes padding (=). This variant is commonly used in URL parameters, JWT tokens, and API communications.
Why convert images to Base64?
Base64-encoded images can be embedded directly in HTML/CSS (data URIs) or included in API request bodies. This eliminates the need for separate file uploads and reduces HTTP requests.
Is my data sent to a server?
No, all conversions happen in your browser. No data is transmitted to any server. Your text and images never leave your device.