Invoicing and expenses, made beautifully simple.
- Project Folio
- Year 2026
- Role Full-Stack Developer
- Stack Next.js, Prisma, Auth.js, Claude
Background
Freelancers and small businesses spend hours every month on invoicing and expense paperwork. Existing tools are either bloated enterprise software or barely-functional spreadsheets — nothing in between feels modern, fast, or simple to use.
Folio is a multi-tenant SaaS that handles the boring parts: send professional invoices in seconds, snap a photo of any receipt and let AI fill in the details, and keep multiple businesses cleanly isolated in separate workspaces.
Challenge
Build a true multi-tenant SaaS where every user can own multiple workspaces, with strict data isolation between them. Each invoice, client, and expense must belong to exactly one workspace, and switching workspaces must feel instant.
On top of that, integrate Claude AI to parse arbitrary receipt photos — extracting vendor, amount, date, and category accurately enough that the user only has to confirm, not retype.
How it works.
Send invoices in seconds
Pick a client, add line items, and Folio handles auto-numbering, tax calculations, and PDF generation. Status tracks from draft to sent to paid — no manual bookkeeping.
AI receipt scanning
Snap a photo of any receipt. Claude extracts vendor name, amount, date, and category in seconds. The user just confirms and saves — no typing required.
Multi-workspace
Run multiple businesses or accounts side-by-side with separate workspaces. Each workspace has its own clients, invoices, expenses, and team members. Switching is instant.
Real-time dashboard
A single overview shows paid lifetime, outstanding balance, active clients, and monthly spend. Recent invoices and expenses surface at the top so nothing slips through.
Under the hood.
| Framework | Next.js 16 (App Router, Server Actions) |
| Database | Postgres + Prisma ORM |
| Auth | Auth.js (NextAuth) with email + OAuth |
| AI | Claude API (vision) for receipt parsing |
| UI | Tailwind CSS + custom components |
| Server-side rendering with React PDF | |
| Hosting | Vercel + Neon Postgres |
Architecture
Features.
What I built.
Multi-tenant data layer
Every Prisma query is automatically scoped to the current workspace through a session-aware middleware. No accidental cross-tenant reads, no hand-written WHERE clauses, no leaks.
Claude vision pipeline
Receipt images are uploaded, sent to Claude with a structured prompt, and parsed into typed JSON. The user gets a pre-filled form with vendor, amount, date, and category — confirm and save in two clicks.
Server-rendered invoices
Invoices render on the server using React PDF, producing pixel-perfect downloads with no client-side library bloat. Users get a polished PDF the moment they click "Download."
Auth + workspace switcher
Auth.js sessions extended with workspace context. The top-right pill ("Mohammed Shafi's workspace") shows the active tenant and switches the entire app's data without a page reload.
Challenges.
Strict tenant isolation
Multi-tenancy is easy to get wrong. I used a Prisma extension that injects workspaceId on every read and write — even a buggy route handler can't leak data because the ORM enforces the boundary.
Reliable AI extraction
Claude is great at OCR but inconsistent on edge cases — handwritten totals, bilingual receipts, faded ink. I added a confidence-aware prompt and always show extracted fields as editable, never auto-saved.
PDF generation cost
Headless Chromium PDFs were too slow and expensive on serverless. Switched to React PDF for a fully streamed, server-rendered approach — sub-second exports, zero cold-start cost.
What's next
Stripe payments directly on invoices so clients can pay with one click. Recurring invoices and subscription billing. Team roles per workspace (admin, member, viewer). Mobile capture flow optimised for snapping receipts on the go.