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How to Use Base64 URL Decoder - Step by Step Guide

Step 1

Input Your Base64url String

Paste the URL-safe Base64 string you want to decode:

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Paste directly: Copy your Base64url encoded string and paste it into the input area
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Upload a file: Click "Upload" to select a file containing Base64url data
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Try the sample: Click "Sample" to load example Base64url data

Example: Base64url Input

Here's an example Base64url encoded string:

SGVsbG8gV29ybGQhIFRlc3RpbmcgKy89IGNoYXJhY3RlcnM
Step 2

Automatic Decoding

The tool automatically decodes your Base64url string back to readable text:

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Real-time decoding: See instant conversion as you type or paste
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Automatic padding: Restores missing = padding characters as needed
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Error detection: Clear error messages if the string is invalid

Example: Decoded Output

The Base64url string decodes to:

Hello World! Testing +/= characters
Step 3

Copy or Download Result

Get your decoded text ready for use:

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Copy to clipboard: One-click copying for quick use
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Download as file: Save the decoded text as a file
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View decoded data: Read the original text content

What Does This Decoder Do?

This Base64 URL Decoder converts URL-safe Base64 strings (Base64url) back to their original text format. It handles the URL-friendly variant that uses different characters than standard Base64.

Decoding Process:

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Converts - back to +
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Converts _ back to /
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Restores padding = characters as needed
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Decodes the resulting standard Base64 to original text

Common Use Cases

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JWT Token Inspection: Decode JWT header and payload sections to view claims
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OAuth Debugging: Extract state parameters from OAuth/SAML responses
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API Response Parsing: Decode Base64url data from REST API responses
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URL Parameter Extraction: Retrieve encoded data from query strings
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Token Validation: Inspect API tokens and access keys

JWT Token Decoding Example

JWT tokens consist of three Base64url encoded parts separated by dots. You can decode the header and payload to inspect the token contents.

JWT Token Structure:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIn0.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

Note: The third part (signature) is binary data and won't decode to readable text.

Frequently Asked Questions

How do I decode a JWT token?

Split the JWT by dots (.) into three parts. Use this decoder to decode the first part (header) and second part (payload). The third part (signature) is binary and used for verification, not decoding.

What's the difference between Base64 and Base64url decoding?

Base64url uses different characters: - instead of +, _ instead of /, and no padding (=). This decoder handles both formats by converting Base64url to standard Base64 before decoding.

Why do I get an error when decoding?

Common errors include: invalid characters in the Base64url string, corrupted data, or mixing standard Base64 with URL-safe Base64. Ensure you're using the correct decoder for your format.

Is it safe to decode JWT tokens here?

Yes for development and learning! All decoding happens client-side in your browser - nothing is sent to servers. However, never decode production tokens containing sensitive data on public tools.

What if my Base64url string has no padding?

No problem! Base64url format typically omits padding (= characters). Our decoder automatically calculates and restores the correct padding before decoding.

Is the Base64 URL decoder completely free?

Yes, totally free with no limitations on usage frequency or features. No registration required, and all decoding happens locally in your browser for complete privacy.

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