itsxcell/inkr-api

AI writing assistant API for African professionals — built with Node.js, TypeScript, Prisma, PostgreSQL, and Groq # Inkr API > AI writing assistant API for African professionals — built for speed, designed for scale. **Live API:** inkr-api.onrender.com **Live App:** inkr-web.vercel.app **Frontend Repo:** itsxcell/inkr-web --- ## What is Inkr? Inkr is a backend API powering an AI writing assistant targeted at African professionals. Users can generate business documents — proposals, emails, pitch decks — using large language models, with a credit-based billing system and Stripe payment integration. This project was built to demonstrate production-grade backend architecture using modern Node.js tooling. --- ## Tech Stack | Layer | Technology | |---|---| | Runtime | Node.js | | Language | TypeScript | | Framework | Express.js | | Database | PostgreSQL (Supabase) | | ORM | Prisma 7 | | AI Provider | Groq (llama-3.3-70b-versatile) | | Auth | JWT + Google OAuth 2.0 | | Payments | Stripe | | Deployment | Render | --- ## Architecture ``` src/ ├── config/ # Passport OAuth strategy ├── lib/ # Shared infrastructure (Prisma, Groq, Stripe clients) ├── middleware/ # JWT authentication, rate limiting └── modules/ ├── auth/ # Register, login, Google OAuth, /me ├── credits/ # Balance, top-up, transaction history ├── generations/ # AI generation, history └── stripe/ # Checkout sessions, webhook handler ``` --- ## Key Design Decisions **PostgreSQL over MongoDB** — relational data fits the billing and credits model. ACID guarantees matter when money is involved. **Abstracted AI provider** — Groq is isolated in `src/lib/groq.ts`. Swapping to OpenAI or Gemini requires changing one file. **Atomic credit operations** — every credit change runs inside a Prisma transaction. Balance update and transaction log always succeed or fail together. **Immutable transaction log** — `CreditTransaction` records have no `updatedAt`. An audit trail you can edit is not an audit trail. **Webhook-driven payments** — credit top …