The build prompt for a billing SaaS with invoice creation, e-invoicing, payment tracking, recurring invoices and a customer portal.
Built for: Startups building tools for freelancers and small businesses
In billing products, accuracy is everything: VAT calculations, currency rounding, e-invoice/e-archive integration and payment reconciliation. One small bug means accounting chaos.
The prompt defines the invoice state machine, tax and rounding rules, e-invoicing integrator webhooks (such as Turkey's GİB integrators) and the customer portal (view, pay, download) in a single architecture.
Each expert adds its own task block, constraints and success criteria to the prompt. Default selection for Invoice & Billing SaaS:
Design the system architecture. Edge-first, 100ms p95. DB schema, API contract, caching strategy, multi-tenancy, RLS, idempotency. Explain why the chosen backend + DB combination is the right call, and write the scaling plan.
Write a flawless PRD. User stories (Jobs-to-be-Done), acceptance criteria, edge cases, metrics (North Star, activation, retention); prioritize the roadmap with RICE. Scope an MVP that ships in 7 days.
Threat model (STRIDE), OWASP Top 10 checklist, auth/session hardening, data classification, GDPR/KVKK compliance map (data inventory, retention periods, deletion flow), audit log schema.
Pricing: Freemium vs. Free Trial, 3 tiers ($19/$49/$149), 20% annual discount, credit system. Hybrid flow with the selected payment providers. Churn-reduction tactics.
Preloaded in step 2 of the Studio; change any of the 7 layers.
Every feature appears in the prompt as a "Spec + API + UI + Tests" line.
Sample idea: "An invoicing tool for freelancers and agencies with e-invoicing support and payment tracking". Below are the master prompt's header and the first expert's block; the Studio generates the full text as 4 experts × 8 steps.
# Invoice & Billing SaaS - MASTER BUILD PROMPT Stack: Next.js 16 (App Router), Hono + CF Workers Goal: An invoicing tool for freelancers and agencies with e-invoicing support and payment tracking This prompt builds a full-stack Invoice & Billing SaaS in 8 steps. Each step consumes the previous step's output. 4 experts' knowledge combined. Steps: 1. PRD & User Stories 2. Design System (Figma tokens) 3. DB Schema & API Contract 4. Auth & Billing Implementation 5. Core Features Build 6. AI Integration (RAG + Agents) 7. SEO/AEO & Analytics 8. Launch & Growth Checklist --- <prompt> <role name="Staff Engineer / CTO" org="ex-Stripe, ex-Vercel" specialty="System Architecture" experience="12y"> You are a Staff Engineer / CTO with 12 years of experience. Specialty: System Architecture. You have shipped world-class products at the level of Stripe, Linear and Vercel. </role> <context> Project: Invoice & Billing SaaS - An invoicing tool for freelancers and agencies with e-invoicing support and payment tracking Type: Invoice & Billing SaaS Vision: Client profiles, quote → invoice conversion, recurring invoices, e-invoice/e-archive submission, online payment links, overdue reminders and revenue reports. Target user: Startups building tools for freelancers and small businesses - Pain: - Budget: Competitors: USP: Monetization: Subscription (MRR), Freemium | Payments: Stripe Tech Stack: Next.js 16 (App Router), Hono + CF Workers, Supabase, Supabase Auth, Resend Features: Email/Pass + Magic Link, Team Invite & Roles, Advanced CRUD + Bulk Ops, Billing & Subscriptions, Notifications Center, Audit Logs, Webhooks & Events Compliance: KVKK/GDPR Lang: EN </context> <task> Design the system architecture. Edge-first, 100ms p95. DB schema, API contract, caching strategy, multi-tenancy, RLS, idempotency. Explain why the chosen backend + DB combination is the right call, and write the scaling plan. General: production quality, copy-paste ready level of detail. </task> <technical_architecture> - Frontend: Next.js 16 (App Router) - App Router, Server Components, partial prerendering - Backend: Hono + CF Workers - Edge runtime, RPC, zod validation - DB: Supabase - pgvector for semantic search, type-safe ORM, RLS policies - Auth: Supabase Auth - Passkeys first, org/team model - Search: - typo-tolerant, faceted - Realtime: Resend - presence, CRDT-ready Payment flow: Stripe -> Webhook -> Background job -> Entitlement update -> Audit log </technical_architecture> <feature_matrix> - [ ] Email/Pass + Magic Link -> Spec + API + UI + Tests …
Submission, status checks and retry-on-error flows for an e-invoicing integrator API (e.g. a GİB-accredited private integrator in Turkey) are included as a separate task.
Amounts are stored as integers in minor units (cents) and VAT is calculated per line item — both are mandatory in the constraints section.
Claude Code, Cursor, Windsurf, v0, Lovable, Bolt and ChatGPT. You pick the output format (Claude XML, ChatGPT Markdown, Cursor Rules, v0, Lovable/Bolt) in step 4 of the Studio, and you can also download it as .cursorrules or CLAUDE.md.
Yes. On the Free plan you generate unlimited prompts with 3 experts and 2 formats — no card required. 18 experts, the Mega Chain and Export to Builders come with Monster Pro ($29/mo).
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Experts, stack and features come preloaded like on this page — you add the name and the idea. Free, no card required.