UNIVERSAL BASE64 DECODER

Decode Standard & URL-Safe Base64 with Multiple Output Formats

100MB Support
Client-Side
Python Logic

Base64 Decoder

Drag & drop your Base64 file or click to browse

Maximum file size: 100MB • One Base64 entry per line

How It Works

1. Input Base64 Data
Upload file or paste text with one Base64 entry per line
2. Automatic Detection
Handles both standard and URL-safe Base64 variants
3. Format Output
Choose between raw text, hex, or custom split formats
4. Download Results
Get decoded data in your preferred format

Supported Base64 Variants

Standard Base64 (A-Z, a-z, 0-9, +, /)
URL-safe Base64 (A-Z, a-z, 0-9, -, _)
Automatic padding handling

Example Input

# Standard Base64
SGVsbG8gV29ybGQh
dGVzdCBkYXRh

# URL-safe Base64
SGVsbG8gV29ybGQh
dGVzdC1kYXRhXw

# Hash examples
5eb63bbbe01eeed093cb22bb8f5acdc3
e3b0c44298fc1c149afbf4c8996fb924

Technical Implementation

Core Features

Universal Decoding

Handles both standard and URL-safe Base64 with automatic detection

Multiple Output Formats

Raw text, hexadecimal, and custom split formats for hash analysis

Large File Support

Process files up to 100MB with efficient client-side processing

Decoding Algorithm

// Base64 decoding with fallback
function base64DecodeSafe(line) {
  // standard Base64 first
  {
    return atob(line);
  } catch (e) {
    // URL-safe Base64 with padding
    let padded = line + '='.repeat((4 - line.length % 4) % 4);
    return atob(padded.replace(/-/g, '+').replace(/_/g, '/'));
  }
}