Tech Strategy for Software Builds

A build-vs-buy decision is the call you make on every component of your software: do you write it yourself, or do you pay a vendor who already solved it. The honest version of build vs buy software is brutal — auth, payments, transactional email, search, error tracking, file storage are solved problems with dozens of mature SaaS providers and free tiers that cover early-stage usage. Build them custom and you've spent a month rebuilding a worse version of Stripe. The tool above runs the build vs buy analysis for every component on your list and names the vendor I'd reach for instead.

Because it consolidates auth, Firestore, storage, functions, hosting, analytics, push, and crash reporting into one platform with one bill. For a small team that's 5-8 fewer vendors than the à la carte equivalent. I've watched founders pick AWS, spend three weeks on IAM and VPCs, and ship nothing. Boring infrastructure ships. Covered in the Default Stack principle.

Then I push back unless you can name one of four override conditions — scale Firestore genuinely can't serve, a team whose existing expertise is non-JS with no time to learn, a regulatory requirement Google Cloud can't meet for your region, or an existing codebase you're not rewriting. "I prefer it" doesn't clear the bar. "AI features" doesn't either — most AI work is API calls that work identically from Node.js.

Build custom is your core domain (the matching engine, the proprietary algorithm). Buy off-the-shelf is a one-time purchase or self-hosted commercial product. Rent SaaS is a managed subscription — Stripe, Resend, Sentry, Firebase. Open source is self-hosted free software where you own the operations cost. For generic domain (auth, payments, email) I almost always pick rent SaaS, because the operations cost of self-hosting eats the savings.

Firebase if you want the most consolidated platform and don't need complex SQL. Supabase if you need PostgreSQL with real foreign keys, complex joins, or row-level security policies you write in SQL. Both are defensible defaults — the tool picks based on your data model, not the trend cycle.

Not for a first version. A monolith on a single platform will outperform a microservice architecture you can't staff. Build a monolith, split later when traffic and team justify it.

Auth, payment processing, transactional email, admin panels, file upload pipelines, push notifications, error tracking, analytics. For each, the tool names the SaaS or Firebase service I'd use and the pricing tier. Once the stack is set, Project Scope turns it into a developer-ready spec.