Index of Coincidence

Index of Coincidence is a free online Text Tools tool that index of Coincidence (IC) is the probability of two randomly selected characters being the same. This can be used to determine whether text is readable or random, with English text having an IC of around 0.066. IC can therefore be a sound m instantly in your browser. Paste your data, adjust the options and get the result in real time — no installation, no sign-up, and nothing is ever uploaded to a server.

How to use: Index of Coincidence →

Description

Index of Coincidence (IC) is the probability of two randomly selected characters being the same. This can be used to determine whether text is readable or random, with English text having an IC of around 0.066. IC can therefore be a sound m

  • This tool runs the official CyberChef engine on the 26173 server. Avoid pasting secrets you would not send to any server.

How to use

Using Index of Coincidence takes three steps:

  1. Paste your data into the input box (or load the example).
  2. Configure the options to match your target format or scenario.
  3. Copy, download or inspect the output — it updates live as you type.

Use cases

Common situations where Index of Coincidence helps:

  • Index of Coincidence (IC) is the probability of two randomly selected characters being the same. This can be used to determine whether text is readable or random, with English text having an IC of around 0.066. IC can therefore be a sound m
  • This tool runs the official CyberChef engine on the 26173 server. Avoid pasting secrets you would not send to any server.

FAQ

What is Index of Coincidence?

Index of Coincidence index of Coincidence (IC) is the probability of two randomly selected characters being the same. This can be used to determine whether text is readable or random, with English text having an IC of around 0.066. IC can therefore be a sound m. It runs entirely in your browser, so your data stays private.

Is Index of Coincidence free to use?

Yes. Index of Coincidence is free, unlimited and works without registration or installation.

Does my data get uploaded?

Is my data uploaded for this tool? — This tool is processed on our server by design; input is used only for the computation and is not stored.

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