One habit per embed: a big check-today button, a live current-streak number, best/total/30d-rate stats, and a GitHub-style heatmap of the last 17 weeks. Tap any past cell to back-fill a missed day; the streak recalculates instantly.
Persistence is local-only — checks live in your browser's localStorage, namespaced by key so multiple embeds stay independent. No accounts, no network, no merge conflicts.
Changes apply live — the embed link on the right and the preview above update instantly.
/embed.Embed link.habit + key.