Base64 Encode / Decode
Encode plain text to Base64, or decode a Base64 string back into readable text.
- Input Characters13
- Output Characters20
Encoding grew 13 input characters into 20 output characters — Base64's 3-bytes-to-4-characters packing adds roughly 33% length.
Base64 packs 3 bytes into 4 characters, so encoded text runs about 33% longer — your 13-character input became 20 characters.
About the Base64 Encode / Decode
This tool encodes plain text into Base64, or decodes a Base64 string back into readable text — a conversion developers run constantly when working with data formats that don't handle raw binary or special characters cleanly.
It's used for embedding small binary data (like an image) inside JSON or a URL, decoding a Base64-encoded JWT payload or API token to see what's inside, preparing email attachment data, or just reading a Base64 string someone pasted into a bug report or config file.
Since encoding and decoding both happen entirely in your browser, it's a safe place to paste something you're not sure is sensitive — an API key or auth token fragment, for instance — without it ever leaving your device.
How it’s calculated
Base64 represents binary data using only 64 printable ASCII characters (A-Z, a-z, 0-9, plus two symbols), which makes it safe to embed inside text-based formats like JSON, XML or URLs that don't reliably handle raw binary or every special character.
The encoding works by packing 3 bytes of input into 4 Base64 characters, which is why encoded output runs roughly 33% longer than the original — that expansion is the tradeoff for making the data universally text-safe.
Frequently asked questions
Is Base64 encoding a form of encryption?
No — Base64 is purely a data representation format, not encryption. It doesn't hide or protect information at all; anyone can decode it instantly, so it should never be used as a substitute for actual encryption when handling sensitive data.
Why does encoded text always come out longer than the original?
Base64 packs every 3 bytes of input into 4 output characters, which mathematically expands the size by about 33% — that overhead is the tradeoff for representing arbitrary binary data using only safe, printable text characters.
Why do I sometimes see a Base64 string end with one or two equals signs?
Equals signs are padding characters, added when the input's length isn't a multiple of 3 bytes — they let the decoder know the final group of characters represents fewer than the usual 3 bytes of original data.
What is Base64 commonly used for?
Embedding image or file data directly inside HTML, CSS or JSON; encoding email attachments (MIME); representing the payload sections of JWTs (JSON Web Tokens) used in authentication; and any other context where binary or special-character data needs to travel safely through a text-only channel.
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