Base64 Encoder Decoder
Convert text to Base64 or decode Base64 back to plain UTF-8 text with fast local processing.
Input
Output
When to Use Base64 Conversion
Base64 is widely used when binary content or special characters must pass through text-only channels. Common examples include API credentials, inline assets, and platform metadata that expects ASCII-safe payloads.
This encoder/decoder is helpful during testing and incident response. You can quickly inspect unknown payloads, verify encoded values, and reduce mistakes before updating configuration files or integration scripts.
FAQ
What is Base64 used for?
Base64 converts binary or text data into ASCII-safe text so it can travel through systems that expect plain text.
Does this tool support non-English text?
Yes. UTF-8 encoding and decoding are handled so Unicode characters are preserved.
Can I decode JWT payload fragments with this tool?
Yes for plain Base64 strings. JWT often uses Base64URL, so replace URL-safe characters if needed before decoding.
Is data sent to a backend service?
No. All Base64 conversion happens locally in your browser session.
Why do I get an invalid Base64 error?
The input may include unsupported characters, missing padding, or be in Base64URL format instead of standard Base64.
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About This Calculator
Encode and decode Base64 strings online with full UTF-8 support. Inspect API payloads, transform values for data URIs, and troubleshoot integration data safely in your browser.
Frequently Asked Questions
Does this Base64 tool support Unicode text?
Yes. It uses UTF-8 conversion so non-English characters including Chinese, Japanese, Korean, Arabic, Cyrillic, and emoji are fully preserved during encoding and decoding.
Can I decode Base64 strings from logs?
Yes. Paste the encoded value and run decode to inspect plain text output.
Are conversions private?
Yes. Conversion runs locally without sending data to a server.
What is Base64 encoding and why is it used?
Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters (A-Z, a-z, 0-9, plus sign, and forward slash). It was originally designed for safely transmitting binary data through text-only channels like email (MIME attachments use Base64 extensively). Today Base64 is widely used in web development for data URIs (embedding small images directly in HTML or CSS as data:image/png;base64,...), encoding authentication credentials in HTTP Basic Auth headers, storing binary blobs in JSON payloads, and transmitting file contents through REST APIs. The encoding increases data size by approximately 33% — every 3 bytes of input produce 4 Base64 characters. Padding characters (=) are appended when the input length is not divisible by 3.
What is the difference between standard Base64 and URL-safe Base64?
Standard Base64 (defined in RFC 4648) uses the characters A-Z, a-z, 0-9, plus (+), and slash (/), with equals (=) for padding. However, plus and slash have special meanings in URLs — plus represents a space in query strings, and slash is a path separator. URL-safe Base64 (also called base64url) replaces plus with hyphen (-) and slash with underscore (_), and typically omits padding. This variant is used in JSON Web Tokens (JWTs), OAuth tokens, and any context where the encoded string appears in a URL. When decoding, you need to know which variant was used, as mixing them produces corrupt output. This tool handles standard Base64 with full UTF-8 support for international text.