Use Base64 for transport compatibility, never as encryption
Base64 represents bytes with printable characters so data can travel through text-oriented systems. Anyone can decode it, the output is larger than the input, and it should not be used to hide secrets.
01 · Step by step
Step by step
Choose text or file mode
Text mode encodes UTF-8 characters. File mode reads the original bytes and is the correct choice for images, PDFs, archives, and other binary data.
Choose the expected variant
Standard Base64 uses + and /. Base64URL replaces them for URLs and tokens. A Data URL adds a media type and prefix for browser embedding.
Encode or decode once
Paste the complete value, preserve meaningful padding, and use the reported error instead of repeatedly modifying an invalid string at random.
Validate in the destination
Test the result in the API, browser, configuration, or application that will consume it. Keep secrets out of shared logs and screenshots even when encoded.
02 · Decision guide
Decision guide
Standard Base64
Common in email, JSON payloads, certificates, and general binary-to-text transport.
Base64URL
Uses URL-safe characters and is common in JWT segments and URL parameters. Padding rules depend on the receiving system.
Data URL
Combines a media type with Base64 data for browser embedding; convenient for small assets but inefficient for large files.
UTF-8 text
Required for reliable multilingual text. A plain browser binary-string method can corrupt non-ASCII characters.
03 · Important limits
Important limits
Base64 is reversible encoding, not encryption, hashing, signing, or access control.
Encoded data is typically about one third larger before any surrounding JSON or Data URL prefix.
Large values are difficult to inspect, copy, log, and transmit; this tool limits files to keep the browser responsive.
Whitespace, missing padding, mixed variants, or an incorrect character set can make decoding fail or produce different bytes.
04 · Common questions
Common questions
Can Base64 protect a password or API key?
No. Anyone who sees the value can decode it. Use proper secret storage and encryption designed for the threat model.
Why is the encoded result larger?
Every three input bytes become four Base64 characters, plus optional padding and any Data URL prefix.
Are values uploaded?
No. Text and file conversion run in browser memory on the current device.
OMNIKIT
A browser-based Base64 encoder and decoder
Use text mode to convert Unicode text with UTF-8, or paste standard Base64, Base64URL, and Data URLs to decode them. File mode reads binary bytes directly and can add a Data URL prefix when needed.
All work happens in browser memory. OmniKit does not upload your input, store results, or put source content into analytics. Files are limited to 20 MB to keep the page responsive.