Developer Tools
Base64 Converter
Encode UTF-8 text as standard Base64 or strictly decode Base64 back to valid UTF-8 text.
Enter the values and review the result.
UTF-8 text conversion
Encode text as canonical standard Base64 or decode canonical Base64 back to valid UTF-8 text.
Maximum 100000 UTF-16 code units. Input is not trimmed, repaired, or silently truncated.
Enter valid input and run the transformation.
How the transformation works
Encode mode converts the entered JavaScript text to UTF-8 bytes, groups those bytes into six-bit values, and maps them to the standard Base64 alphabet. Padding with one or two equals signs is included when required.
Decode mode validates the complete canonical string, decodes its bytes, checks canonical re-encoding, and then performs fatal UTF-8 decoding. Whitespace, unpadded input, URL-safe characters, malformed padding, noncanonical trailing bits, and arbitrary non-text bytes are rejected.
Reconstructable examples
Hello World becomes SGVsbG8gV29ybGQ=. The check mark ✓ is encoded as UTF-8 bytes and becomes 4pyT. Decoding either canonical string returns the original text.
These examples demonstrate UTF-8 text encoding. They do not demonstrate encryption, hashing, compression, secrecy, or file conversion.
Assumptions and limitations
The input is treated as text exactly as represented by the text field. Standard Base64 is case-sensitive. Decode mode requires canonical padding and valid UTF-8 output. This route does not accept MIME line wrapping, URL-safe Base64, files, images, credentials, encrypted content, or arbitrary binary payloads.
Transparency note
Accuracy and limitations
Calzivo tools are built for practical estimates, conversions, and checks. Some tools use standard formulas or simplified assumptions, and results can be affected by input accuracy, rounding, units, local rules, or changing official requirements.
Results depend on the values you enter and any simplified assumptions used by the tool. Verify important results before making decisions or submitting official information.
Reference check
Sources and references
These references provide background context for the topic. They do not replace official advice or documents for personal decisions.
- RFC 4648: Base-N Encodings
Internet Engineering Task Force
- Encoding Standard: UTF-8
WHATWG
How to Use This Tool
Use these steps to enter the right inputs and interpret the result correctly.
Choose whether to encode UTF-8 text or decode canonical standard Base64.
Enter text without relying on automatic trimming or correction.
Run the transformation and review the complete output.
Copy only the primary transformed text or reset the tool.
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Related Guides
Background reading and explanations related to Base64 Converter.
Frequently Asked Questions
Common questions about Base64 Converter and how to read the result.
Is Base64 encryption?
No. Base64 is reversible encoding and does not protect passwords, tokens, secrets, or private information.
Does this support Unicode text?
Yes. Encode mode converts JavaScript text to UTF-8 bytes before Base64 encoding, and decode mode requires valid UTF-8 text.
Can I decode URL-safe Base64?
No. This route accepts canonical standard Base64 using + and / with required padding, not the URL-safe - and _ alphabet.
Can this convert files or arbitrary binary data?
No. This public workflow is limited to UTF-8 text. Use a dedicated file or image workflow for binary data.
Why was valid-looking Base64 rejected?
The input may be unpadded, contain whitespace, use URL-safe characters, have invalid trailing bits, or decode to bytes that are not valid UTF-8.