# Regular Expressions

> Editing the regular expressions that custom formats match against.

A page from the Profilarr documentation, last updated 2026-10-01 (commit: https://github.com/Dictionarry-Hub/profilarr.com/commit/92a5c54a149c3c94cd38a300e6082dc70a368f93). Web version: https://profilarr.com/build/regular-expressions. Edit on GitHub: https://github.com/Dictionarry-Hub/profilarr.com/edit/develop/src/routes/(docs)/build/regular-expressions/+page.svx

TODO: Editing regular expressions. Covers the Blank and Release Group presets, writing patterns that are checked against the .NET regex engine Radarr and Sonarr use, linking a Regex101 ID, and how regular expressions reach your Arrs only through the custom formats that use them.

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