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Found code with no history and no author? Paste it in. The carbon dater looks for features and habits that were only in fashion for a few years and estimates when it was written.
Found some code and have no idea how old it is? Paste it in. The carbon dater looks for fossils (language features, libraries, and habits that were only in fashion for a few years) and estimates when it was written, from COBOL to the age of AI agents. Runs in your browser; your code goes nowhere.
Accuracy: about as good as real carbon dating performed by a raccoon. For the real age, use git log --reverse. For modernizing it, the AI Code Reviewer helps.
100 of 102 run entirely in your browser (Weather Widget uses Open-Meteo; What's My IP asks this site's server).
Share on XShare on LinkedInCode carries its era with it. `var self = this` comes from before arrow functions. `$(document).ready` is peak jQuery. `print "hello"` is Python 2. Optional chaining, React hooks, and f-strings are newer. Each pattern has a window of years when people wrote it, and the overlap of those windows is a decent guess at when the code was written.
The dater weights about 40 of these fossils, takes any copyright year as strong evidence, and flags files that mix ancient and modern code, which usually means a partial renovation. It's for fun, but it's a quick way to judge how scary an unfamiliar file is before you touch it. For the real date, check `git log`.