Base64URL Encoder/Decoder

Encode and decode Base64URL (URL-safe Base64 variant used by JWT/JWS/JWE), with conversions between standard and URL-safe Base64

Key Facts

Category
Conversion & Encoding
Input Types
textarea, select
Output Type
text
Sample Coverage
4
API Ready
Yes

Overview

The Base64URL Encoder/Decoder is a specialized utility designed to convert text and binary data to and from the URL-safe Base64 variant (RFC 4648 / RFC 7515) commonly used in JWT, JWS, and JWE. It also enables seamless conversion between standard Base64 and Base64URL formats, with support for UTF-8 and Hex output encodings.

When to Use

  • •When generating or parsing JWT headers and payloads that require URL-safe Base64 encoding without padding characters.
  • •When transmitting binary data or tokens via URL query parameters where standard Base64 characters like '+' and '/' could cause routing or parsing issues.
  • •When converting existing standard Base64 strings into the URL-safe Base64URL format, or vice versa.

How It Works

  • •Input the text, standard Base64, or Base64URL string into the input area.
  • •Select the desired operation: Encode to Base64URL, Decode from Base64URL, Standard to Base64URL, or Base64URL to Standard.
  • •Choose the output encoding format (UTF-8 text or Hex string) if you are decoding.
  • •The tool processes the input instantly and displays the converted output.

Use Cases

Debugging and inspecting JWT tokens by decoding the header and payload segments.
Preparing binary identifiers or tokens for safe transmission in URL query parameters.
Converting legacy standard Base64 database entries into URL-safe strings for API integrations.

Examples

1. Decoding a JWT Payload Segment

Web Developer
Background
A developer needs to inspect the JSON payload of a JWT token received from an authentication service to verify the user claims.
Problem
The payload is encoded in URL-safe Base64 without padding, making it unreadable.
How to Use
Paste the payload segment of the JWT into the input field, select 'Decode from Base64URL' as the operation, and set the output encoding to 'UTF-8 text'.
Example Config
operation: "decode", outputEncoding: "utf-8"
Outcome
The tool outputs the decoded JSON string containing the user claims.

2. Converting Standard Base64 to URL-Safe Base64

API Integrator
Background
An integrator has a standard Base64 encoded API key containing '+' and '/' characters that needs to be passed as a URL path parameter.
Problem
The standard Base64 characters will break the URL routing.
How to Use
Paste the standard Base64 string into the input field and select the 'Standard → Base64URL' operation.
Example Config
operation: "to-base64url"
Outcome
The tool replaces '+' with '-', '/' with '_', removes the trailing '=' padding, and outputs the URL-safe string.

3. Encoding a String to Base64URL

Security Engineer
Background
A security engineer needs to encode a custom token string into a URL-safe format for a webhook payload.
Problem
The token must be transmitted safely in a URL without escaping special characters.
How to Use
Input the raw token text, select 'Encode to Base64URL' as the operation, and run the encoder.
Example Config
operation: "encode"
Outcome
The input is encoded into a compact, URL-safe Base64URL string.

Try with Samples

base64, text
Hex/Unicode Encoding Format Samples
Examples of hex (\xXX) and unicode (\uXXXX) escape sequence encoding formats
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Comprehensive JWT examples from basic token structure to advanced security implementations
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FAQ

What is the difference between standard Base64 and Base64URL?

Base64URL replaces the '+' and '/' characters of standard Base64 with '-' and '_', and omits the '=' padding characters to make the string safe for URLs and filenames.

Can I decode a JWT payload using this tool?

Yes, you can paste individual segments of a JWT (header or payload) and decode them from Base64URL to UTF-8 text.

Does this tool support decoding to hexadecimal format?

Yes, you can set the output encoding option to Hex string when decoding Base64URL.

Why does Base64URL omit the '=' padding characters?

The '=' character is often URL-encoded or has special meaning in query strings, so Base64URL strips it to prevent transmission issues.

Is this tool compliant with RFC standards?

Yes, the encoding and decoding processes follow the specifications outlined in RFC 4648 and RFC 7515.

API Documentation

Request Endpoint

POST /en/api/tools/base64url-encoder

Request Parameters

Parameter Name Type Required Description
inputText textarea Yes -
operation select Yes -
outputEncoding select No -

Response Format

{
  "result": "Processed text content",
  "error": "Error message (optional)",
  "message": "Notification message (optional)",
  "metadata": {
    "key": "value"
  }
}
Text: Text

AI MCP Documentation

Add this tool to your MCP server configuration: 

{
  "mcpServers": {
    "elysiatools-base64url-encoder": {
      "name": "base64url-encoder",
      "description": "Encode and decode Base64URL (URL-safe Base64 variant used by JWT/JWS/JWE), with conversions between standard and URL-safe Base64",
      "baseUrl": "https://elysiatools.com/mcp/sse?toolId=base64url-encoder",
      "command": "",
      "args": [],
      "env": {},
      "isActive": true,
      "type": "sse"
    }
  }
}

You can chain multiple tools, e.g.: `https://elysiatools.com/mcp/sse?toolId=png-to-webp,jpg-to-webp,gif-to-webp`, max 20 tools.

If you encounter any issues, please contact us at [email protected]