massCode allows you to organize snippets using multi-level folders as well as tags. Each snippet has fragments - tabs, which gives even greater level of organization.
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Pros
Pro Free
This is free and asks for donations. Recommend donating, this tool is fantastic.
Pro Available for Linux, Windows and MacOS
Pro Simple, clean interface
Pro Multiple languages for the same snippet
A single code snippet can have multiple "fragments" of code written in different languages.
Pro Tags
Snippets can be sorted and organized using tags.
Pro VSCode Integration
There's a Visual Studio Code extension that lets you search and insert massCode snippets.
Pro Open Source
The entire code base is available on GitHub.
Pro Prettify
Uses Prettify for code formatting.
Cons
Con No cloud syncing
While you can set the data to be saved on a cloud drive, you can't have another instance of the program using that same folder.
Con Electron is a memory hog
This app is built with NodeJS and uses the Electron, VueJS, and ACE packages.