A Build Kit to help you build your own version of a Time Tracking & Invoicing App using AI coding agents like Claude Code, Codex, or Gemini.
What you'll build
A lean app for people who bill by the hour. You track time against a client's project with a start/stop timer — or log it by hand — and the running timer follows you around the app while you work. When it's time to get paid, you pick a client and a date range, and every unbilled hour turns into an itemized, client-ready invoice automatically. No re-keying, no spreadsheets.
It stays deliberately simple: one user, one currency, no payment gateways. The whole point is the shortest path from "I did the work" to "here's the invoice" — with the math frozen the moment you generate, so changing a rate later never rewrites money you've already billed.
Who it's for
Solo professionals who bill by the hour and want to stop wrestling with spreadsheets and clunky tools:
- Freelancers and independent consultants
- Bookkeepers and accountants
- Virtual assistants
- One-person agencies and studios
What it solves
- Tracking billable hours across different clients and projects without losing track of what's unbilled.
- Turning a month of logged time into a polished invoice without re-typing every line.
- Keeping past invoices accurate even after you raise your rates.
- Knowing, at a glance, how many hours are unbilled and how much money is still owed.
Key user flows
- A user can add clients with a default hourly rate, and projects under them with an optional rate override.
- A user can start and stop a live timer on a project — and the timer keeps running as they move around the app.
- A user can log time manually with a project, date, and duration.
- A user can review all their time in one list, filter it, edit or delete entries, and see running totals of hours and value.
- A user can generate an invoice from a client and date range, with unbilled hours grouped into per-project line items and totals frozen at that moment.
- A user can download a clean, client-ready PDF showing their business name, logo, and address.
- A user can move an invoice from Draft to Sent to Paid, and void one to return its hours to the unbilled pool.
- A user can open a dashboard that shows total unbilled hours and total outstanding invoices up front.
How you'll build it
- Project setup & base infrastructure — scaffold the app, sign-up/login, the app shell, and light/dark mode.
- Clients & projects — manage who you bill and the work you do, each with an hourly rate.
- Time tracking & review — the persistent timer, manual entries, and a review list with running totals.
- Invoicing & PDF — auto-built invoices, a downloadable PDF, and the Draft → Sent → Paid lifecycle.
- Dashboard & polish — at-a-glance totals, quick actions, and a mobile-friendly pass across the app.
What's included
README.md— orientation and how to use the kit_build_plan/PRD.md— the product requirements, data model, and milestone breakdown_build_plan/tech-stack.md— customizeable tech stack for your codebase_build_plan/design-system.html— visual reference (colors, type, components — open in a browser)_build_plan/milestones/<N>-<slug>/prompt.md— one folder per milestone with a lean, ready-to-paste prompt that works with any AI coding agent
