Solo OS
Solo OS

Base64 Encoder / Decoder

Encode or decode Base64 strings instantly — zero dependencies, 100% local.

Plain Text
Base64 Output
Base64 encode and decode locally — and understand what it is not
Base64 is an encoding, not encryption. It exists to move binary data through channels that only reliably carry text, such as email bodies, JSON fields and data URIs. It is trivially reversible by anyone, which is worth stating plainly because Base64 is regularly used as though it hides something. This tool encodes and decodes in your browser with full Unicode support, so the string you are working with stays on your device.
How This Local-First Tool Works
  • Encoding inflates size by roughly a third. Three bytes of input become four characters of output, which is why embedding a large image as a data URI makes a page heavier, not lighter.
  • Naive Base64 breaks on non-ASCII input. Text containing accented characters, Devanagari or emoji has to be UTF-8 encoded before conversion, which is a common source of mangled output in hand-rolled implementations.
  • Anyone can decode it. Base64 in a config file, a URL parameter or a token payload is obfuscation at best — if the content is sensitive it needs actual encryption, not an encoding.
  • URL-safe Base64 substitutes - and _ for + and /, because the standard alphabet includes characters that have meaning in a URL. Decoding a URL-safe string with a standard decoder is a frequent cause of failures.
Frequently Asked Questions
Is Base64 encryption?
No. It is a reversible encoding with no key and no secret. Anyone who has the string can recover the original in one step. If you need something to be unreadable to a third party, you need encryption.
Why does my decoded text come out as garbage characters?
Almost always a character-set mismatch: the original was UTF-8 but is being decoded as Latin-1, or the reverse. Anything outside plain ASCII — accents, Indian language scripts, emoji — surfaces the problem immediately.
What is a data URI and when should I use one?
A data URI embeds a file directly in HTML or CSS as a Base64 string, removing a network request. It is worth it for a tiny icon and counterproductive for anything larger, since the payload cannot be cached separately and costs a third more bytes than the original file.
Is my input sent to a server?
No. Encoding and decoding happen in your browser. That is relevant when the string is a JWT or an API payload, both of which routinely carry credentials that should not be pasted into an unknown site.
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