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Definition

What is Base64?

Base64 is an encoding that turns any binary data — images, files, credentials — into a string of 64 safe ASCII characters that can travel through text-only systems.

Also called: base 64 encoding · b64

Base64 uses the characters A–Z, a–z, 0–9, +, and / (plus = for padding) to represent three bytes of binary as four printable characters. That's about a 33 % size overhead, which is fine for small payloads.

Common uses: embedding tiny images directly in HTML/CSS as data URLs, encoding binary attachments in email (MIME), sending API keys or tokens in HTTP headers, and storing small blobs in JSON.

Base64 is encoding, not encryption — anyone can decode it in one line of code. Treat Base64 strings as if they were the raw bytes underneath.

Try a tool that uses Base64

Base64 Encoder

Encode any UTF-8 text to a Base64 string.

Base64 Decoder

Decode Base64 strings back to readable text.

Base64 Image Converter

Convert any image to a Base64 data URL and back.

Related definitions

JWT (JSON Web Token)

A JWT is a compact, URL-safe token made of three Base64 parts — header, payload, signature — used to prove who is making an API request.

Regex (Regular Expression)

A regex is a mini-language for describing text patterns — used to find, validate, or replace substrings in a larger body of text.

Cron

Cron is a Unix scheduler that runs commands on a recurring timetable — every minute, every Monday at 6 AM, the first of every month, and so on.

Hash Function

A hash function maps any input — a password, a file, a message — to a fixed-length string that acts as a fingerprint of the original.