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Free Online Base64 Encoder & Decoder

Convert text and files to Base64 format and vice versa. Secure, fast, and 100% client-side.

All conversion happens locally in your browser. Nothing you paste — including API keys — is ever sent to our servers.
Input
Text
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Secure Base64 Conversion in Browser

The Base64 Encoder & Decoder is a powerful tool allowing you to convert text and files into Base64 format and back, directly within your browser. No software installation or account required.

Privacy First

All processing happens locally on your device via JavaScript. Your data is never sent to our servers, ensuring maximum privacy for sensitive information like API keys or private data.

Features

  • Text & Files: Convert both text strings and files (images, PDFs, etc.) to Base64.
  • UTF-8 Support: Full support for special characters and emojis.
  • URL Safe: Option to generate URL-safe Base64 strings.
  • Instant: Real-time conversion with no server latency.

Frequently Asked Questions

Convert text and files to Base64 format and decode them back instantly. Safe for sensitive API keys.

No. All conversion happens locally in your browser using native JavaScript APIs.

Yes. You can upload files to convert them to Base64 strings without uploading them to any server.

Yes. It fully supports UTF-8, ensuring special characters and symbols are encoded correctly.

It replaces standard Base64 characters (+ and /) with URL-friendly alternatives (- and _) to safely use strings in URLs.

No. Base64 is an encoding scheme, not encryption. It transforms data into a text-safe format but does not provide any security. Anyone can decode a Base64 string.

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts arbitrary binary data into a subset of ASCII characters. It is widely used to safely transmit binary content (images, files, keys) through text-only channels like email or JSON APIs. encrypt text with AES for secure storage.

The name "Base64" comes from the 64-character alphabet used: A-Z, a-z, 0-9, +, and /. Each 3 bytes of input become 4 Base64 characters, resulting in approximately 33% size overhead. convert between JSON, CSV, XML and more.

// ASCII alphabet used
A-Z  a-z  0-9  + /
// URL-safe variant
A-Z  a-z  0-9  - _

How to Encode or Decode in 3 Steps

01

Choose a Mode

Select "Encode" to convert plain text or binary content to Base64, or "Decode" to reverse a Base64 string back to its original form.

02

Paste or Upload

Type or paste your text, or upload a file. Text encoding works directly; binary file encoding uses the FileReader API in-browser.

03

Copy or Download

Copy the result to clipboard with one click, or download it as a .txt file. No server involved — processing is 100% local.

Encoding in Action: Plain Text → Base64

Plain Text Input 
Hello, CharCount! 🔐
Base64 Encoded Output 
SGVsbG8sIENoYXJDb3VudCEg8J+Qkw==

Encoding vs Decoding — When to Use Which

When to Encode

Use encoding when you need to embed binary data in a text-safe format: embedding images in CSS/HTML, storing binary blobs in JSON, or passing data through a URL parameter.

When to Decode

Use decoding when you receive a Base64 string from an API, an email attachment header, or a config file and need to inspect or use the original content.

URL-Safe Base64 Mode Explained

Standard Base64 uses "+" and "/" which are reserved characters in URLs. URL-safe mode replaces them with "-" and "_", making the output safe for use in URLs, query parameters, and JWT tokens without encoding.

Toggle "URL Safe" mode in the options bar before encoding to get a URL-ready Base64 string every time.

Common Base64 Use Cases

Embedding images inline in HTML or CSS (data URIs)
Encoding binary files for transmission in JSON APIs
Storing credentials in HTTP Basic Auth headers
Generating JWT token payloads and signatures
Inspecting Base64-encoded email attachments (MIME)

Base64 Is Encoding, Not Encryption

A critical misconception: Base64 is NOT a security measure. Anyone can decode a Base64 string in seconds. Never use it to "hide" passwords, API keys, or sensitive data.

For security, use proper encryption (AES, RSA) or hashing (bcrypt, SHA-256). Base64 is purely for safe text transport of binary data.

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Encode Files to Base64

Need to embed a small image in a CSS file or send a PDF through a JSON API? Upload a file and get its complete Base64 string representation instantly.

Supports any file type. Larger files (5MB+) may take a moment to process. The output is a pure ASCII string ready to paste anywhere.

Technical Reference: Base64 Alphabet

Base64 uses 64 printable ASCII characters: uppercase A-Z (26), lowercase a-z (26), digits 0-9 (10), and two special chars (+ and /). The "=" padding character aligns the output to block boundaries.

This tool uses the browser-native btoa() and atob() APIs for standard encoding and decoding, ensuring cross-platform reliability.

A-Z   a-z   0-9   + /   = (padding)

Common Base64 Mistakes to Avoid

Forgetting padding "=" at the end — base64 strings must have a length divisible by 4.

Using standard Base64 in URLs — always switch to URL-safe mode to avoid percent-encoding issues.

Treating Base64 as encryption — it provides zero security, only encoding.

Quick Tips for Working with Base64

1 Add data:image/png;base64, before your Base64 string to use it directly as an image src.
2 JWT tokens are three Base64URL-encoded parts separated by dots — decode each part independently.
3 GitHub and other platforms use Base64 for file content in their APIs — use this tool to inspect any file response.

Encode or Decode Your Data Instantly

Paste your text or upload a file above — results appear immediately. Free, private, browser-only.

Encode / Decode Now