Flowfolio

What it is A Notion template for freelancers who bill through Stripe: two linked databases (Clients, Deals) with Kanban, Calendar, and List views, kept in sync automatically — when a client pays, the deal card moves itself to "Paid" instead of you dragging it by hand.

Components & how it works

The product itself lives in Notion — no separate app to log into. Deals has a Status select (Proposal → Sent → Paid / Failed / Refunded), a relation to Clients, and date/amount properties; the same data drives all three views (Board grouped by status, Calendar keyed on payment date, List sorted by value) for free, since they're just different lenses on one database.

The relay — a single Next.js API route (/api/stripe-webhook) deployed as a Vercel serverless function, on the buyer's own free Vercel account.

Event handling — Stripe's SDK (stripe.webhooks.constructEvent) verifies each request's signature before anything else runs (anything unsigned gets a 401); a small dispatcher routes four event types — checkout.session.completed, invoice.paid, invoice.payment_failed, charge.refunded — to their own handler.

Notion API (@notionhq/client) — each handler looks up the matching Deal page by its stored Stripe Invoice ID and updates its Status and Payment Date properties directly.

Idempotency — an in-memory set of processed Stripe event IDs prevents a re-delivered webhook (Stripe retries if it doesn't get a fast 200) from double-updating the same deal.

No database of its own — the relay is stateless glue between Stripe and Notion; it runs entirely inside the buyer's own Stripe, Notion, and Vercel accounts, so no third party (including the seller) ever touches their payment data.