Foam is described as 'personal knowledge management and sharing system inspired by Roam Research, built on Visual Studio Code and GitHub' and is an app in the Office & Productivity category. There are more than 100 alternatives to Foam for a variety of platforms, including Online / Web-based, Windows, Mac, Android and Linux. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Google Keep. Other great apps like Foam are Obsidian (Free Personal), Notion (Free Personal), Microsoft OneNote (Freemium) and Evernote (Freemium).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.