(Update June 2024 - there is a standalone version that is downloadable here https://civicrm.org/download - currently beta)

No, CiviCRM must be installed within one of these CMS platforms: Drupal, Wordpress, Joomla, or Backdrop. But this doesn't mean you need to use *that* CMS for your organization's main website — you can install CiviCRM (within one of those CMS platforms) on a subdomain. 

The CMS handles the part of the application which deals with *users* (i.e. "reset my password" and other such functionality). The fact that CiviCRM delegates this functionality to the CMS does make it a tiny bit more complicated — but tremendously more flexible! For example, perhaps in 10 years your very small organization will have grown to the point where it *wants* a CMS which can integrate with its CRM. CiviCRM leaves that possibility open. 

### Suggestions for you

* Install CiviCRM with Wordpress (the simplest one)
* Or, if the installation process feels daunting, consider hiring a [hosting provider](https://civicrm.org/partners-contributors?country=All&services=Hosting&language=All&cms=All) to set up and maintain a CiviCRM installation for you

Instead of viewing the CMS as "massive overkill" I would encourage you to think of it as only one small piece of CiviCRM itself. It just happens to be a *modular* piece. The size and complexity of an empty CMS actually pales in comparison to the size and complexity of CiviCRM itself.