What is Base64 Validation?
Base64 validation checks whether a string is properly encoded according to the Base64 specification. Valid Base64 strings use only the characters A-Z, a-z, 0-9, +, and /, with = used for padding. The validator verifies the character set, checks padding correctness, and can detect the image format if the string represents image data.
Why Validate Base64 Strings?
Validating Base64 strings is crucial for debugging and quality assurance. Invalid Base64 can cause applications to crash or display errors when decoding. Validation helps identify truncated or corrupted data, detect encoding errors before they reach production, and verify that API responses contain properly formatted image data. For developers working with Base64 data, validation is an essential step in ensuring data integrity.
How This Validator Works
This tool performs comprehensive validation on your Base64 string. It checks character validity, ensuring only permitted Base64 characters are used. It verifies padding correctness, checking that = characters appear only at the end. It detects data URI prefixes and extracts format information. It estimates the decoded size and attempts to decode the string to verify it represents valid data. For image data, it tries to load and preview the image to confirm validity.
Common Validation Errors
Several issues can make a Base64 string invalid. Invalid characters outside the Base64 alphabet will cause validation to fail. Incorrect padding with = characters in wrong positions indicates corruption. Truncated strings that end abruptly suggest incomplete data. Whitespace or line breaks within the encoded string can cause parsing errors. This validator identifies these issues and provides clear feedback to help you fix the problem.
Base64 String Structure
A valid Base64 string follows specific rules. It uses only 64 specific characters plus padding. The length must be a multiple of 4 when fully padded. Padding characters (=) can only appear at the end. Data URIs include a prefix like "data:image/png;base64," before the encoded data. Understanding this structure helps identify why validation might fail and how to fix invalid strings.
Frequently Asked Questions
How do I validate a Base64 string?
Paste your Base64 string into the text area above. The validator will instantly check if it's properly formatted, detect the image format, and provide detailed feedback about any issues.
What makes a Base64 string invalid?
A Base64 string is invalid if it contains characters outside of A-Z, a-z, 0-9, +, /, and =. It's also invalid if the length isn't a multiple of 4 (when padding is included) or if padding characters appear in incorrect positions.
Can this validator detect the image format?
Yes. If your Base64 string includes a data URI prefix (like "data:image/png;base64,"), the validator will extract the format. It can also detect the format by examining the decoded binary data's file signature.
Why does my valid-looking Base64 fail validation?
Common causes include whitespace or line breaks in the string, incomplete or truncated data, or incorrect padding. The validator will provide specific error messages to help identify the issue.
Is this validator safe for sensitive data?
Yes. All validation happens locally in your browser. Your Base64 data never leaves your device, ensuring complete privacy and security.