Overview
Encode and decode Base64 strings instantly
Base64 is a way to represent binary data using only 64 ASCII characters: A to Z, a to z, 0 to 9, plus, slash, and equals for padding. The point is to take data that might contain arbitrary bytes (images, file contents, encrypted blobs) and encode it as plain text that can travel safely through systems designed for text only: email, JSON payloads, URL parameters, XML attributes, and source code.
ToolHub Base64 Encoder converts text to Base64 and back. It handles UTF-8 properly, so emoji and non-Latin scripts round trip correctly. Everything happens in your browser.
Step-by-step
How to use Base64 encode and decode
- 1
Pick a mode
Encode converts plain text to Base64. Decode does the reverse, converting Base64 back to readable text. - 2
Type or paste your input
Drop your text or Base64 into the input panel. The output updates as you type. - 3
Copy or swap
Click copy to grab the result. The swap button reverses input and output, useful for round-tripping.
Background
What Base64 actually does
Base64 takes 3 bytes (24 bits) of input and encodes them as 4 ASCII characters (each carrying 6 bits). The output is always about 33 percent larger than the input. If the input length is not a multiple of 3, padding equals signs are added at the end to make the output length a multiple of 4.
Why “not encryption” matters
Base64 is encoding, not encryption. Anyone can decode a Base64 string back to its original. It hides nothing. Putting a password in Base64 in code or in a URL is exactly as insecure as putting the plain text. If you need privacy, use encryption (AES, libsodium, or HTTPS), not Base64.
UTF-8 and emoji
Standard Base64 only handles bytes. To encode text, you first need to convert the text to bytes using UTF-8. Our encoder does this automatically, so you can encode emoji, Hindi, Chinese, Arabic, or any other text without corruption.
Use cases
When to use Base64
Embedding images in CSS or HTML
Use data URIs (data:image/png;base64,...) to inline small images directly in stylesheets or markup.
Email attachments
MIME email standards use Base64 to send binary attachments through text-only email infrastructure.
JSON binary fields
JSON does not have a native binary type. Encode binary data as Base64 strings to include it in API payloads.
Authentication tokens
JWT tokens use Base64URL (a slight variant) to encode their three parts: header, payload, signature.
Storing files in databases
Some legacy systems store small binary files as Base64 text columns, which is simple if not space-efficient.
URLs with binary data
Pass small binary blobs through URL parameters by Base64-encoding them first.
Tips and best practices
- Base64 increases size by 33 percent. For large files, gzip first then Base64.
- Avoid Base64 in URLs unless necessary. Plus and slash characters can cause problems. Use Base64URL variant if you must.
- Never use Base64 for security. It is encoding, not encryption.
- When decoding fails, the input is malformed. Check for missing padding or unexpected characters.
- Newlines in Base64 output are decorative only and are ignored by decoders.
Common questions
Why is the encoded output larger than my input?
Base64 represents 3 bytes as 4 characters, a 33 percent size increase. Plus padding can add up to 2 more characters at the end. This overhead is the cost of guaranteed safe text transport.
Why does my decoded text have garbage characters?
The original encoder might have used a different encoding (Latin-1, Windows-1252) instead of UTF-8. Our decoder uses UTF-8 which is the modern standard. Mismatched encodings produce garbage on round-trip.
What is Base64URL?
A variant of Base64 designed for URLs. It replaces plus with dash, slash with underscore, and removes padding equals signs. Used in JWT tokens and modern web APIs.
Can I encode files?
The current tool encodes text. To encode an arbitrary file as Base64, drop it into a tool that reads files (or open the devtools console and use FileReader API).
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