I'm systematically replacing my SaaS subscriptions with Single Serving Applications -- purpose-built, AI-generated apps designed for an audience of one. Each clone is built by Claude Opus 4.6 from a requirements document, runs via Docker Compose, and costs essentially nothing to operate.
This page is a running catalog of every clone I've built. I'll add a new entry each time I replace another subscription.
About the author: I'm Charles Sieg -- a cloud architect and platform engineer who builds infrastructure for Fortune 1000 clients through Vantalect. If your organization is rethinking its software strategy in the age of AI-generated code, let's talk.
Harvest Clone
Time tracking and invoicing for consultants.
| Replaces | Harvest ($180/year) |
| Source Code | GitHub |
| Blog Post | Claude Opus 4.6 vs GPT-5.3-Codex: Building a Full Web App From Scratch |
| Built With | React, Python/Flask, PostgreSQL |
| Build Time | 18 minutes |
| Lines of Code | ~4,700 |
| Tests | 32 (21 backend + 11 E2E) |
The Harvest clone covers time entry with an editable week grid, expense tracking with file attachments, project management grouped by client, invoice creation with a multi-step wizard, PDF generation, reports with CSV export, and a full settings page. It reproduces Harvest's orange brand identity and card-based layout. The week view is an actual editable grid -- just like the real Harvest -- where you can click into cells and enter hours directly.
This was the clone that started it all. It was built as a head-to-head benchmark between Claude Opus 4.6 and GPT-5.3-Codex. Claude's version covered 97% of Harvest's features. Codex's version was functional but architecturally compromised. I'm using Claude's version daily.
Trello Clone
Kanban boards for personal project management.
| Replaces | Trello |
| Source Code | GitHub |
| Blog Post | Using Claude to Clone Trello in 20 Minutes |
| Built With | React, Node.js/Express, PostgreSQL |
| Build Time | 19 minutes |
| Lines of Code | ~6,800 |
| Tests | 52 (38 backend + 14 E2E) |
A full-featured Kanban board with drag-and-drop list and card reordering, markdown descriptions with auto-save, color-coded labels, checklists with progress bars, due dates with overdue indicators, global search, card filtering, a command palette (Cmd+K), keyboard shortcuts, dark mode, and full workspace export/import. Claude even wrote the requirements document and technical design -- my total input was two prompts.
The Pattern
Every clone follows the same process:
- Write (or generate) a requirements document. Be specific about the data model, the views, the workflows.
- Hand it to Claude Opus 4.6 with a prompt to build a Dockerized full-stack application.
- Walk away. Come back in ~20 minutes to a running app.
- Validate and iterate. Test it for a few days alongside the SaaS product.
- Cancel the subscription.
Average build time so far: 18.5 minutes. Average cost: a few dollars in API tokens. Combined annual savings: $180+ and counting.
The source code for every clone is available on GitHub. Clone the repo, run docker compose up --build, and see for yourself.