Ask HN: What are some lesser-known social apps that you use?

Social media is dominated by big well-known players (Facebook/Insta, TikTok, Snapchat, Reddit, Twitter) and the internet is feeling increasingly small to me.

Years ago we had more options such as digg, myspace, friendster, orkurt, bebo, even google+.

What are some lesser-known social apps that you use?