sync with Steam
Import
sync with Epic Games
Import
sync with GOG
Import
import from Playnite
Import
import from IsThereAnyDeal
Import
HLTB
Import
Grouvee
Import
import from text
Import
GG.Deals doesn't offer an export function, and Backloggd has it on their public roadmap. In the meantime, you can try importing a text list.

Import from Grouvee

1. Sign in to Grouvee
Make sure you're signed in at grouvee.com before continuing.
2. Export your collection
From your Settings page, click Export your collection to a CSV file near the bottom. Instead of downloading it directly, Grouvee will email you a link.
3. Upload the ZIP here
and check the results
Done? Check your profile and playlist