# Does Nightfall have a regex library I can choose from?

Yes! While Nightfall's pre-built detectors listed above are trained via machine learning, Nightfall also supports [RE2](https://github.com/google/re2/wiki/Syntax) regexes and word lists for any custom detectors that may be of interest to you. Over time, we've aggregated the following [**Regex Library**](https://airtable.com/embed/shrTrBDgr36xTI2QF?backgroundColor=purple\&viewControls=on), which you're welcome to select from to save you some time.

Please note that a regular expression is an established yet limited method that searches for pre-defined patterns, so your mileage may vary.

You can test regular expressions [**here**](https://regex-golang.appspot.com/assets/html/index.html).

You can input custom detectors directly in the Nightfall console at [app.nightfall.ai](https://app.nightfall.ai/) by navigating to [Detectors](https://app.nightfall.ai/detection-engine/detectors) → **New Detector** → **Regular expression**.