Base64 Encode and Decode
Encode plain text to Base64 or decode Base64 strings back to plain text directly in your browser. Full support for international UTF-8 characters, emojis, and URL-safe formatting.
How to use
Select your desired operation from the mode selector: Encode or Decode.
Type or paste your text into the input pane, upload a text file, or click Try an example.
If encoding for query parameters or web tokens, optionally enable URL-safe (RFC 4648) mode.
View the instant real-time result in the output pane.
Click Copy to copy the result to your clipboard or Download to save a local text file.
What is Base64 encoding and why is it used?
Base64 is a widely used binary-to-text encoding algorithm designed to safely transport binary data across communication channels that were originally designed to handle plain ASCII text (such as email via SMTP, HTTP headers, URLs, and JSON payloads). Base64 takes arbitrary bytes and encodes them using an alphabet of 64 printable characters: uppercase letters A-Z, lowercase letters a-z, digits 0-9, plus signs +, and forward slashes /, with equals signs = used for padding.
Standard Base64 vs URL-Safe Base64 (RFC 4648)
In standard Base64 encoding, the characters + and / are used for indices 62 and 63. However, in web URLs, query parameters, and filenames, these characters hold reserved semantic meanings:
- A plus sign
+is frequently interpreted by web servers as a space. - A forward slash
/is interpreted as a path delimiter. - Equals signs
=are reserved for query parameter key-value pairs.
To resolve these ambiguities, RFC 4648 Section 5 defines URL-Safe Base64 (also known as base64url). It substitutes - (hyphen) for +, _ (underscore) for /, and omits the trailing = padding characters. This format is the foundation of modern technologies like JSON Web Tokens (JWT) and WebAuthn credentials.
Handling international UTF-8 characters and Unicode
A classic bug in JavaScript web tools is passing multi-byte Unicode strings (such as accented letters, Chinese characters, or emojis) directly into the legacy btoa() browser function. Because btoa() expects 8-bit Latin1 characters, it throws an InvalidCharacterError when encountering code points higher than 255. This tool implements the modern TextEncoder and TextDecoder web standards, ensuring every international script and emoji is converted into proper UTF-8 byte sequences before Base64 transformation.
Is Base64 encryption?
No. Base64 is an encoding format, not encryption. It provides zero cryptographic protection and can be trivially decoded by anyone who inspects the data. Never use Base64 alone to obscure passwords, API keys, personal identifiable information (PII), or confidential data without an underlying encryption layer such as AES-GCM or TLS.
Complete local privacy guarantee
Developers frequently decode sensitive tokens, configuration strings, and authentication payloads during debugging sessions. Sending those strings to third-party online decoders risks logging them in remote server access logs. This tool runs 100% locally in your web browser. No network requests are made, ensuring your data never leaves your workstation.
Frequently asked questions
Does this tool transmit my text to any server?
No. The entire encoding and decoding process runs locally in your browser's JavaScript engine. Your inputs and outputs never leave your device.
What is the difference between standard and URL-safe Base64?
Standard Base64 uses '+' and '/' with '=' padding. URL-safe Base64 (RFC 4648) replaces '+' with '-' and '/' with '_', and strips padding so the string can be safely placed in URLs and HTTP headers.
Why do some Base64 strings end with '=' or '=='?
Base64 processes data in 3-byte blocks. If the input data is not an exact multiple of 3 bytes, '=' characters are appended as padding to complete the final 4-character block.
Does this tool support emojis and non-English text?
Yes. This tool uses native UTF-8 encoding (TextEncoder/TextDecoder) so Chinese, Arabic, Cyrillic, accented characters, and emojis encode and decode with 100% fidelity.
Is Base64 secure for storing passwords?
No. Base64 is an encoding scheme, not encryption. Anyone can decode a Base64 string instantly. Passwords should always be hashed using strong cryptographic algorithms like Argon2 or bcrypt.