I built a small web app that allows to create retrospective boards with four columns: Glad (what went well), Wonder (questions), Sad (improvements), and Action (follow-ups). It's anonymous and collaborative: anyone with access to a session link can add, edit, vote, or delete cards.

I found that, apart from using hackpads or similar text-based tools, there weren't many solutions for quickly collaborate on such retrospective sessions without disclosing everyone's name. So I built this. It also works well with a mix of offline and online: first everyone can take time to add ideas and vote on them at their own pace, then everyone can meet in person to collectively decide on next steps.