JSON Formatter and Validator
Paste JSON to format it with 2 spaces, 4 spaces or tabs, or minify it to one line. The formatter validates as you type and points to the exact line and column of any error, such as a trailing comma or single quotes.
Base64 Decode and Encode
Paste Base64 to decode it to readable text, or paste text to encode it. Accents, Cyrillic and emoji work in both directions, and the URL-safe variant used in JWTs and URLs is one switch away: "SGVsbG8sIHdvcmxkIQ==" decodes to "Hello, world!".
The preview is shortened. Copy and Download include the whole result.
Your text never leaves your device.
How to use
- Choose Encode to turn text into Base64, or Decode to turn Base64 back into text.
- Paste your input. Turn on URL-safe for Base64url (- and _ instead of + and /, no = padding).
- Copy the result. If the input is not valid Base64, the message says what is wrong and where.
Examples
- Before
- Hello, world!
- After
- SGVsbG8sIHdvcmxkIQ==
- Before
- привет 👍
- After
- 0L/RgNC40LLQtdGCIPCfkY0=
- Before
- привет 👍
- After
- 0L_RgNC40LLQtdGCIPCfkY0
- Before
- SGVsbG8
- After
- Hello
How encoding works
Base64 takes the bytes of your text three at a time (24 bits) and writes them as four characters of 6 bits each. If the last group has only one or two bytes, the output is padded with = or ==: “a” encodes to “YQ==”, “ab” to “YWI=”. So the encoded text is always about a third longer than the original: 3 bytes in, 4 characters out.
Text is converted to bytes as UTF-8 first. That is why “привет 👍”, 8 characters, becomes 24 Base64 characters: each Cyrillic letter takes 2 bytes and the emoji takes 4, 17 bytes in all. Tools that skip the UTF-8 step (such as the browser’s bare btoa function) fail on anything outside Western European letters.
Errors the decoder catches
- Unexpected character: Base64 contains only letters, digits, + / - _ and =. “abc*” fails at position 4. Watch for characters picked up while copying, such as quotes or a trailing period.
- Wrong length: valid Base64 never leaves a single character in the last group of four, so a string of that length was cut off while copying.
- Not text: the data decodes to binary, such as an image, not to UTF-8 text.
Common mistakes
- Treating Base64 as a way to hide data. It is readable by anyone. Encrypt secrets and use Base64 only to transport the result.
- Mixing up standard and URL-safe output. A server expecting standard Base64 may reject - and _. Match what the receiving system expects.
- Encoding text that is already encoded. Encoding twice gives a longer string that decodes to Base64, not to your text. If the output looks like Base64, decode again.
- Using Base64 for large files in web pages. A data: URL is a third larger than the file and cannot be cached separately. Keep it for small icons.
Frequently asked questions
How do I decode Base64?
Select Decode and paste the Base64 string. The decoded text appears immediately. Padding (=) is optional, standard and URL-safe characters are both accepted, and line breaks inside the input are ignored, so Base64 copied from an email source or a PEM file decodes as is.
What is Base64 used for?
Base64 turns any bytes into 64 safe characters (A–Z, a–z, 0–9, + and /) so that binary data can travel through systems built for text. You meet it in email attachments, data: URLs for images, the parts of a JSON Web Token, HTTP Basic authentication headers, and API fields that carry files or keys.
Is Base64 encryption?
No. Base64 is an encoding: anyone can decode it, without a key, in one step. It hides nothing. Never use it to protect passwords or secrets; a Basic auth header or a JWT payload is readable by anyone who sees it.
What is URL-safe Base64 (Base64url)?
Standard Base64 uses + and /, which have special meanings in URLs, and = padding. Base64url (RFC 4648 section 5) replaces + with - and / with _ and usually drops the padding. JWTs, many OAuth parameters and file names use it. Turn on URL-safe to encode in this form; decoding accepts both forms automatically.
Why does decoding say the result is not text?
Base64 can contain any data: images, PDFs, compressed files. If the decoded bytes are not valid UTF-8 text, the tool tells you instead of showing unreadable characters. A string starting with iVBORw0KGgo is a PNG image, for example, and /9j/ is a JPEG.