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Base64 Encoder / Decoder

Base64 that handles UTF-8 properly, plus URL-safe output and file to data URI.

Runs in your browser · No upload Works offline
Base64 result
SGVsbG8sIFRvb2x1bGFoISDwn5GL
Input (UTF-8 bytes)
21
Result length
28 chars
Size change
+33.3%

File → Base64 / Data URI

Or drop a file onto this area. Up to 10 MB; the file is never uploaded.

Text and files are converted in your browser only and are never uploaded.

How to use

  1. Choose Encode and type some text — the Base64 appears instantly. Text is converted to UTF-8 bytes first, so accented letters, CJK and emoji survive the round trip.
  2. Choose Decode and paste a Base64 string to get the original text back. Line breaks, missing = padding and URL-safe characters (- _) are handled automatically.
  3. Turn on URL-safe when the value goes into a URL or file name: - and _ replace + and /, and trailing = is dropped.
  4. In the File → Base64 section, convert an image or any other file (up to 10 MB) to Base64 or a data: URI.

How Base64 works

Base64 (RFC 4648) splits every 3 bytes (24 bits) into four 6-bit groups and maps each to one of 64 characters. Output is therefore about 33% larger than the input, and = pads the end when the length isn’t a multiple of 3.

Variant Alphabet Padding Used in
Standard Base64 A–Z a–z 0–9 + / = Email attachments (MIME), data URIs, HTTP Basic auth
URL-safe (base64url) A–Z a–z 0–9 - _ usually omitted JWTs, URL parameters, file names

Examples

Input UTF-8 bytes Base64
Hi 2 SGk=
é 2 (C3 A9) w6k=
Hello 👋 10 SGVsbG8g8J+Riw==

An emoji takes 4 bytes in UTF-8, so it adds more to the Base64 output than a plain letter does.

Things to know

  • Base64 is not encryption. Anyone can decode it instantly, so never use it to hide passwords or keys. To check integrity, use the Hash Generator.
  • If decoded bytes aren’t valid UTF-8 (an image or PDF, say), you’ll see the first bytes in hex and can save them as a binary file.
  • Inlining large images as data URIs in HTML or CSS defeats caching and bloats the page. It’s best kept for icons of a few KB.

FAQ

Why do other tools garble non-English text?

The browser’s built-in btoa/atob only handle single-byte (Latin-1) characters, so text outside that range throws an error or comes out garbled. This tool uses TextEncoder/TextDecoder for exact UTF-8 conversion.

Is my text or file uploaded?

No. Everything is converted inside your browser and nothing is sent over the network, so it’s safe for auth tokens and internal files.

How do I read what’s inside a JWT?

Each JWT segment is base64url-encoded JSON. The JWT Decoder splits out the header and payload and shows the expiry time.

URL Encoder / DecoderPercent-encode and decode text, and break any URL into its parts. JWT DecoderRead a JWT and check when it expires — the token is never sent anywhere. Hash GeneratorFive hashes of any text or file at once, with checksum comparison. JSON FormatterFormat, minify and validate JSON — errors pinpointed by line and column.

Coming soon

XML Formatter Coming soonPretty-print XML with clean indentation and spot syntax errors. SQL Formatter Coming soonFormat messy or one-line SQL queries with readable line breaks and indentation. HTML Beautifier & Minifier Coming soonTidy HTML with proper indentation, or minify it by stripping whitespace. CSS Beautifier & Minifier Coming soonFormat CSS for readability, or minify it by removing whitespace and comments. JavaScript Beautifier & Minifier Coming soonFormat JavaScript for readability, or minify it to shrink file size. Markdown Preview Coming soonWrite Markdown, see the rendered result live and export it as HTML.

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