How I Built a Functional Billing App in ~2 Hours Vibe Coding with Grok Build (Terminal Agent, No Traditional Coding)
A couple months back I shared how I stood up a complete Travel Log/Planner app (travel.jdb.net) over a weekend using ChatGPT 5.5. It was a solid vibe-coding experience—full CRUD, search, import/export, PDF generation—and the post got good traction from other IT pros tired of boilerplate drudgery.
This time I wanted something more operational for my property management work. A straightforward CLI app for generating invoices, tracking payments, handling my real estate tenants and client projects, with export options and basic reporting. Nothing fancy, but secure, practical, and useful day-to-day.
The whole thing, including installing and learning Grok Build, took me right around 2 hours. Here's how it went and why this tool feels like a meaningful step up.
The Setup (15-20 minutes)
I asked Grok how to start with Grok Build and followed the simple instructions.
Opened a fresh directory in PowerShell, typed grok, authenticated, and I was in the Terminal User Interface (TUI). No IDE extensions, no project templates to wrestle with. It just read the empty folder and was ready.
First prompt was simple: “Build an app to generate invoices. Include client/project management, invoice creation with line items, payment tracking, PDF export, and basic auth. Prioritize security and clean code.” I told Grok Build where the Excel and PDF invoices I was manually generating were and it used them as a template for the app.
Grok Build went into planning mode, asked a few clarifying questions, laid out the structure, and started building. Subagents handled frontend, backend logic, and even some test data in parallel.
I reviewed generated files, asked for some changes, and iterated with natural follow-ups. The next step was to ask Grok Build to set up my computer to run the app monthly and send me an email indicating that the process was run. Now I have invoices ready to email every 15th of the month.
Finally, I asked Grok Build to backup to my GitHub and remember to update GitHub if I make changeds.
Contrast with the Travel App (ChatGPT 5.5 Era)
The Travel Planner was a great proof-of-concept. ChatGPT handled most of the heavy lifting in the chat window, but I was still copying chunks, managing context manually, and doing more glue work myself. It took a full weekend of back-and-forth because the conversation would drift or lose nuance on larger refactors.
Grok Build feels different right in the terminal:
Deep repo awareness from the start—no need to keep feeding it files.
Plan → Approve → Execute workflow that keeps things disciplined.
Multi-file edits and terminal execution (no install, builds, git commits) without leaving the session.
I stayed in flow longer. The agent handles grunt work while I focus on business logic (like tenant-specific invoice rules or capital gains notes for my properties).
Result: Same “I didn’t really code this” feeling, but faster and with fewer context resets. The Travel app was weekend-warrior mode; The billing app was “I have client work this afternoon” mode.
Grok Build vs Codex: The Real Delta
I’ve used Codex. It’s excellent for generating solid code snippets and filling functions. But it’s still mostly a smart autocomplete on steroids inside an editor.
Grok Build is a full coding agent living in your terminal:
It owns the project lifecycle—planning, architecture decisions, parallel subagents for different concerns, running tests/builds, and even git integration.
Stronger at staying on task across a whole app without constant prompting.
The TUI with Plan Mode and approve workflows reduces hallucinated changes I’d have to chase down later in pure Codex flows.
Security-aware defaults and practical defaults align well with how I work (no fluff, focus on reliability for client-facing or financial tools).
Codex is still great for quick one-offs. Grok Build wins when you want an autonomous partner that treats the entire codebase as context and ships working end-to-end programs.
What I Actually Got
A clean, functional billing app with:
Client invoice tracking
Invoice generation (line items, totals, notes)
PDF exports
Basic auth and data persistence
It’s already handling real data and ready for me to integrate further. Exactly the kind of internal tool that saves me (and potentially clients) hours every month.
Bottom Line
Grok Build isn’t magic—it still requires clear direction and occasional course corrections—but it compresses real development work dramatically. Two hours from zero to usable app is the kind of productivity that makes solo consulting sustainable.
If you’re an IT leader, consultant, or technical founder tired of context-switching between chats and editors, give the CLI a spin. For security reasons I won’t be open-sourcing a version of billing app.