Text to Base64 Encoder & Decoder
Encode plain text to Base64 or decode Base64 strings back to readable text. Fast, secure, client-side processing with live preview and JSON formatting.
What is Base64 and why do we use it?
Base64 is an encoding system designed to represent bytes as readable text using an alphabet that is safe for any digital channel. It transforms groups of three bytes into four ASCII characters, preventing mail headers, web forms, or logging systems from rejecting the information.
The conversion introduces roughly a 33% increase compared with the original size. That expansion is the cost of ensuring compatibility, but it is acceptable when you need to transmit certificates, API keys, small images, or embedded JSON snippets. If the string begins with symbols such as +, /, or ends with equal signs, that is expected—padding is part of the specification.
How does the conversion work?
Take the word "Sol" and see how it travels from ASCII to Base64.
| Original characters | S | o | l |
|---|---|---|---|
| ASCII value | 83 | 111 | 108 |
| Bits | 01010011 | 01101111 | 01101100 |
Grouping in Base64
24-bit sequence: 010100110110111101101100
Six-bit blocks: 010100, 110110, 111101, 101100
Decimal indexes: 20, 54, 61, and 44 → Base64 characters: U29s
The result is U29s. If the original message did not align to a multiple of three bytes, Base64 would add one or two = signs to complete the final 24-bit block.
Best practices for encoding
- Keep your text in UTF-8 before converting so you avoid unreadable characters when retrieving the content.
- Add line breaks every 76 characters only if an older specification (such as MIME) requires it.
- Combine Base64 with encryption when handling sensitive information—encoding alone will not provide security.
When decoding is useful
- Inspect HTTP requests or JWT tokens to understand which fields are hidden inside the payload.
- Check obfuscated logs before storing them in analytics databases.
- Validate attachments in support tickets or emails without downloading potentially harmful files.
This online decoder automatically analyses spaces and line breaks, normalises URL-safe variants, and in live mode applies the conversion as you type.
FAQs
Does Base64 encoding make my data secure?
Base64 is not an encryption algorithm—it simply represents binary data using a safe character set. Pair it with proper encryption if you need confidentiality.
Can I decode URL-safe Base64 values?
Yes. Replace hyphens with plus signs and underscores with forward slashes before decoding, or paste them directly—Base64decode normalises whitespace automatically.
What limits should I expect?
The browser handles large strings well, but Base64 inflates content size by roughly 33%. Keep that in mind when sharing encoded text.