Excalidraw's hand-drawn look is free — Excalidraw+ only buys you cloud collab
I almost passed on the cute hand-drawn flowchart style, assuming it sat behind a subscription. It doesn't. The hand-drawn aesthetic is Excalidraw's default and only style, and it's completely free. The paid tier, Excalidraw+, is team cloud collaboration and version history — nothing to do with how the diagrams look.
mermaid.live is the same story: the official open-source editor for Mermaid.js, free, no credits, no pay-per-render. The "credit-based" impression usually comes from third-party SaaS tools that generate Mermaid from a prompt.
So going from a flowchart to a hand-drawn version costs nothing. Get your flowchart as Mermaid (write it, or hand a vision-capable AI a photo of your sketch), then paste it straight onto the Excalidraw canvas — it detects the syntax and pops a "Parse as Mermaid" import dialog. There is no Insert → Mermaid item in the hamburger menu or toolbar (those only have Open / Save / Export / Live Collaboration); the other entry point is the command palette (Ctrl/Cmd + /) → search Mermaid.