Project: BaaS vs Custom Backend

function compareArchitectures(app) {
  const baas = {
    approach: "BaaS (Supabase/Firebase-style)",
    devSpeed: "Fast: auth, database, and realtime sync are provided out of the box, so there is far less custom code to write and test.",
    control: "Lower: business logic is constrained to what the BaaS SDK, database rules, and realtime hooks allow.",
    costStructure: "Usage-based pricing from day one; near-zero cost while small, but it can rise quickly at scale.",
    portability: "Lower: the schema, auth, and realtime wiring are tied to that provider's SDK and conventions.",
    complexityGrowth: "Bolting on custom business logic beyond simple CRUD and rules gets progressively harder."
  };

  const customBackend = {
    approach: "Custom backend on a PaaS",
    devSpeed: "Slower start: auth, schema, and realtime sync all have to be designed, built, and tested by hand.",
    control: "Higher: full control over business logic, data model, and the realtime implementation.",
    costStructure: "Predictable compute and database cost, but you pay for infrastructure even at low usage.",
    portability: "Higher: it's a standard backend codebase and database that can move between PaaS providers.",
    complexityGrowth: "Scales cleanly as business logic grows, since it is already an ordinary application codebase."
  };

  let leansTowards;
  if (app.timeToMarketPriority === "high" && app.expectedComplexityGrowth !== "high") {
    leansTowards = "BaaS - speed to ship matters more here, and the logic isn't expected to outgrow it soon.";
  } else if (app.expectedComplexityGrowth === "high" || app.teamSize === "large") {
    leansTowards = "Custom backend - complex logic or a larger team benefits more from full control than from speed.";
  } else {
    leansTowards = "Either is defensible - revisit this once real usage patterns and team size are clearer.";
  }

  return { app: app.name, baas, customBackend, leansTowards };
}

const noteApp = {
  name: "NoteSync (notes app with accounts + realtime sync across devices)",
  timeToMarketPriority: "high",
  expectedComplexityGrowth: "low",
  teamSize: "solo"
};

console.log(JSON.stringify(compareArchitectures(noteApp), null, 2));