What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts binary data into a string of ASCII characters. It uses 64 characters — A-Z, a-z, 0-9, +, and / — plus = for padding. The result is roughly 33% larger than the original data, but it's safe to embed in text-based formats.

Why Base64 Exists

Many protocols and formats — email (MIME), JSON, HTML, URLs — are designed for text, not binary. Base64 bridges the gap by letting you safely embed binary data (images, files, cryptographic keys) inside text-only contexts.

Common Use Cases

  • Data URIs — embed small images directly in HTML or CSS: data:image/png;base64,iVBOR...
  • Email attachments — MIME encodes files as Base64
  • JWT tokens — the header and payload are Base64url-encoded JSON
  • API payloads — send binary data in JSON fields
  • Basic auth — HTTP Basic Authentication encodes user:password as Base64

When NOT to Use Base64

Base64 is not encryption. Anyone can decode it instantly. Never use it to hide sensitive data. Also avoid it for large files — the 33% size overhead adds up. Use proper file uploads or streaming instead.

Encode and Decode Instantly

Use the Base64 Encoder on CodeKitLab to encode or decode any string. Working with images? The Image to Base64 tool converts any image to a data URL, HTML tag, or CSS background. Need to go the other way? Base64 to Image lets you paste a data URL and preview or download the image.

Base64 in JavaScript

In the browser, use btoa() to encode and atob() to decode. In Node.js, use Buffer.from(str).toString('base64'). For URL-safe Base64, replace + with - and / with _.

Quick Reference

  • Input: 3 bytes → Output: 4 characters
  • Padding: = or == added when input isn't a multiple of 3
  • URL-safe variant: replaces +/ with -_

Base64 is one of those things every developer encounters but few truly understand. Now you do — and you have the tools to work with it instantly.

Base64-kodning forklarat

Base64 konverterar binar data till ASCII-text. Det anvands i data-URIs, JWT-tokens och e-postbilagor. Koda och avkoda med Base64 Encoder. For bilder, anvand Image to Base64.

Base64-Kodierung erklart

Base64 konvertiert Binardaten in ASCII-Text. Es wird in Data-URIs, JWT-Tokens und E-Mail-Anhangen verwendet. Kodieren und dekodieren Sie mit dem Base64 Encoder. Fur Bilder nutzen Sie Image to Base64.

L'encodage Base64 explique

Base64 convertit les donnees binaires en texte ASCII. Il est utilise dans les Data URIs, les tokens JWT et les pieces jointes. Encodez et decodez avec le Base64 Encoder. Pour les images, utilisez Image to Base64.

Codificacion Base64 explicada

Base64 convierte datos binarios en texto ASCII. Se usa en Data URIs, tokens JWT y archivos adjuntos. Codifica y decodifica con el Base64 Encoder. Para imagenes, usa Image to Base64.

ترميز Base64 موضح

يحول Base64 البيانات الثنائية إلى نص ASCII. يُستخدم في Data URIs وتوكنات JWT والمرفقات. قم بالترميز وفك الترميز باستخدام Base64 Encoder. للصور، استخدم Image to Base64.

Base64 انکوڈنگ کی وضاحت

Base64 بائنری ڈیٹا کو ASCII ٹیکسٹ میں تبدیل کرتا ہے۔ یہ Data URIs، JWT ٹوکنز اور ای میل اٹیچمنٹس میں استعمال ہوتا ہے۔ Base64 Encoder سے انکوڈ اور ڈی کوڈ کریں۔ تصاویر کے لیے Image to Base64 استعمال کریں۔