Base64 Encode / Decode

What it does

Converts text to

Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

and back. Pick Encode or Decode, paste your input, and the output appears instantly - no button to press. The converter handles multi-line input, flags invalid

Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

instead of guessing, and carries your text and direction in a share link so a colleague opens the exact same conversion.

How to use it

1. Choose the direction: Encode (text →

   Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

   ) or Decode (

   Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

   → text).
2. Paste into the Input box. The conversion runs as you type.
3. Copy the output, or copy a share link that carries both the input and the direction.
4. Malformed

   Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

   (wrong characters, broken padding) shows an error instead of silent garbage - fix the input and it recovers on the next keystroke.

Examples

Direction	Input	Output
Encode	Hello, CosmoDev!	SGVsbG8sIENvc21vRGV2IQ==
Decode	Q29zbW9MYWJz	CosmoLabs
Encode	multi\nline	bXVsdGkKbGluZQ==

What

Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

is (and is not)

Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

maps any 3 bytes onto 4 characters from a 64-letter alphabet (A-Z, a-z, 0-9, +, /, padded with =), so binary data can travel through channels that only move text - data URLs, JSON fields, email MIME parts, HTTP Basic auth headers.

Two properties matter:

• It is reversible, not secret. Anyone can decode the output; there is no key. Never treat

  Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

  as encryption or as a way to hide credentials.
• It inflates by ~33%. Three bytes become four characters, so a 3 MB file becomes a 4 MB string. Fine for tokens and small payloads, poor for large media.

A close cousin, Base64url (used by JWTs), swaps +→- and /→_ and drops the = padding so the string is safe inside URLs. This tool’s Decode accepts ordinary

Base64Base64An encoding representing binary data as 64 safe ASCII characters, so it survives transport through text-only channels. It encodes — it does not encrypt.

; for

JWTJWTA compact, URL-safe token that carries claims (like identity or expiry) between two parties, signed to prevent tampering.Learn more

work use the JWT Debugger, which handles the base64url variant end to end.

Good to know

• Invalid input (a stray character, truncated padding) shows Invalid Base64 input - the converter refuses to guess rather than emit mojibake.
• UTF-8 is honored end to end: accented characters and emoji encode and decode round-trip correctly.
• Private: conversion runs locally in your browser. Nothing you paste is transmitted.
• Related tools:

  JWTJWTA compact, URL-safe token that carries claims (like identity or expiry) between two parties, signed to prevent tampering.Learn more

  Debugger, URL Encode / Decode,

  HashHashA one-way function that maps data of any size to a fixed-length digest. Same input, same digest; any change, different digest; not reversible.

  Generator.