Base64 Encoder & Decoder - Free Online Tool

Encoding Text to Base64

1. Select the Encode tab at the top.
2. Enable Live Preview to see the result as you type.
3. Type or paste any text - plain text, JSON, XML, credentials, HTML, or any Unicode string.
4. The encoded Base64 string appears instantly in the output panel.
5. Click Copy to copy the result to your clipboard.

Decoding Base64 to Text

1. Select the Decode tab.
2. Paste your Base64-encoded string into the input field.
3. The decoded plain text is shown instantly in the output panel.
4. If the Base64 string is malformed, a clear error message is displayed.
5. Click Copy to copy the decoded output.

HTTP Basic Authentication

The HTTP Basic Auth scheme requires credentials in the format username:password, Base64-encoded and passed in the Authorization header. For example, user:pass encodes to dXNlcjpwYXNz. This is not encryption - it only enables safe transport over ASCII-only HTTP headers. Always use HTTPS alongside Basic Auth.

JSON Web Tokens (JWT)

The header and payload sections of a JWT are Base64URL-encoded (a variant that uses - and _ instead of + and / for URL safety). Decoding a JWT header or payload manually is a frequent debugging task - you can use this tool to quickly inspect what claims a JWT carries without writing code.

Embedding Images in HTML/CSS (Data URIs)

Small icons and inline images can be embedded directly in HTML or CSS using data URIs: src="data:image/png;base64,iVBORw...". This eliminates an HTTP request for each image and is popular for inlining SVGs, favicons, and small background textures in frameworks and email templates.

Email Attachments (MIME)

Email servers were historically built to carry 7-bit ASCII text. MIME (Multipurpose Internet Mail Extensions) uses Base64 to encode attachments - PDFs, images, and any binary file - so they survive the text-only transport without corruption. RFC 2045 defined this standard, making Base64 a prerequisite for modern email infrastructure.

REST APIs and JSON Payloads

JSON does not natively support binary data. When APIs need to transmit images, audio, or binary files within JSON, Base64 encoding converts the binary to a string field. Base64-encoded file uploads are common in chat APIs, document generation services, and OCR or vision AI APIs that accept images as base64 strings.

Cryptographic Keys and Certificates

PEM (Privacy Enhanced Mail) format - the standard for SSL/TLS certificates, SSH keys, and GPG keys - uses Base64 to encode the underlying DER binary data between -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- markers. Inspecting or converting certificates frequently requires Base64 decode operations.

Subresource Integrity (SRI)

When loading scripts or stylesheets from a CDN, browsers verify resource integrity using hashes encoded as Base64 in the integrity attribute: integrity="sha256-abc123...". Generating or verifying SRI hashes requires Base64 encoding of the SHA-256 or SHA-384 digest.

Configuration Files and Environment Variables

Multi-line secrets (private keys, certificates, JSON credentials) are often Base64-encoded to store them as single-line environment variables in CI/CD pipelines, Kubernetes secrets, and Docker configs. Encode with this tool, store the value, and decode at runtime.

JavaScript (Browser)

// Encode
const encoded = btoa(unescape(encodeURIComponent("Hello 🌍")));

// Decode  
const decoded = decodeURIComponent(escape(atob(encoded)));

Python

import base64

# Encode
encoded = base64.b64encode("Hello".encode()).decode()

# Decode
decoded = base64.b64decode(encoded).decode()

Node.js

// Encode
const encoded = Buffer.from("Hello").toString("base64");

// Decode
const decoded = Buffer.from(encoded, "base64").toString("utf8");

PHP

// Encode
$encoded = base64_encode("Hello World");

// Decode
$decoded = base64_decode($encoded);