What Is Base64?
The Base64 Encoder & Decoder converts text to and from Base64, the encoding scheme that represents binary data as plain ASCII characters. Base64 is everywhere in modern development: data URLs for inline images, JSON Web Tokens (JWT), email attachments, HTTP Basic Auth headers and API payloads that must travel safely through text-only channels. This tool encodes and decodes full UTF-8, so accented characters, symbols and emoji round-trip correctly. The auto-detect mode inspects your input and decides whether to encode or decode for you, while manual Encode and Decode modes give you full control. Everything runs locally in your browser, so even sensitive tokens never leave your device.
Base64 is an encoding scheme that converts binary data — bytes with any value from 0 to 255 — into a string of printable ASCII characters. It was designed to safely carry binary content (images, files, executable code) through systems that were built to handle text, such as email, URLs and HTML attributes. The name comes from the 64-character alphabet it uses: A–Z, a–z, 0–9, + and /.
How to Use the Base64 Tool
- Pick a mode: Auto detects encode vs decode automatically, or force Encode or Decode.
- Type or paste your text or Base64 string into the input area — the result appears instantly below.
- Click the copy button to copy the output, or Clear to start over.
Use Cases
- Embedding images directly in HTML or CSS as data: URIs, avoiding an extra HTTP request.
- Decoding JWT payloads or other API tokens that are Base64-encoded.
- Safely passing binary content through a URL or JSON field that expects text.
- Inspecting or encoding configuration values, secrets or file attachments in email.
How Base64 Encoding Works
The encoder reads the input three bytes at a time (24 bits) and splits them into four 6-bit groups. Each 6-bit value maps to one character in the 64-character alphabet, producing four ASCII characters for every three bytes. If the input length is not a multiple of three, one or two = padding characters are added to complete the last group.
Decoding reverses the process: each character maps back to its 6-bit value, groups of four are merged into 24 bits, then split into three bytes. Padding = characters tell the decoder how many real bytes are in the final group.
Benefits and Use Cases
- Quickly inspect or build data URLs, decode JWT payloads, and debug API responses that contain Base64 fields.
- Full UTF-8 support means accented text and emoji encode and decode without corruption.
- Runs entirely in your browser, so confidential tokens or payloads are never sent to any server.
Privacy
Encoding and decoding happen entirely in your browser. The data you enter is never uploaded or stored on our servers. Everything runs in client-side JavaScript on your own device.