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Decode double URL encoding

Apply URL decoding twice to expose a value that was encoded in two layers.

Install in Serialize

What it can do

  • Reveal the first percent-encoding layer
  • Decode residual escapes
  • Make ambiguous parameter data visible

How the recipe works

URL Decode

Decode the outer transport layer.

URL Decode

Decode percent signs that were protected by the first layer.

Demonstration

Sample input

username=Dang&password=foo%2532%26%5E2&referrer=Hacker+M%CE%BFon

Expected result

password=foo2&^2

When to use it

  • Secure-coding classes
  • Proxy-log inspection
  • Finding normalization mismatches

Adapt it

Step through one decoder at a time. Repeated decoding can change delimiters and must match the application under study.

Source and verification

Adapted from Coventry University: encoding exercises. The explanation and sample are written for Serialize, use synthetic or documentation-safe data, and are checked against the current operation catalogue. The workflow runs locally without an external API call.

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