A standard for personal AI-built tools.
For when a spreadsheet is too weak and SaaS is too much. One HTML file. Runs offline. Leaves the chat.
AI has made personal software viable. Flatpack solves the form factor.
One file
The artifact is the program. Save it, send it, open it later. No install.
Local-first
No network calls, no embedded secrets, no telemetry. Owns its data.
Agent-editable
A different AI agent, six months on, can change it without breaking it.
Try one in your browser
Each link opens a real, working Flatpack — single HTML file, no setup. Click Load sample data once it opens. Save it locally if you want to use it again later.
- Invoice cleaner CSV in, validated rows out
- Client quote Days × rate → printable proposal
- Case chronology Dated event log with tags
- Checklist Sectioned progress + notes
- Report builder Guided form → Markdown
- Decision tree Branching questions → recommendation
- Calculator Inputs → result → print summary
- CSV cleaner Generic CSV validator
What this is
Flatpack is a specification, not a product. It tells an AI coding agent how to produce a single-file local HTML tool with a stable internal structure — section markers, a manifest, inline tests, AI-editing notes — so the result is portable, inspectable, and editable by a different agent later. The spec is mechanically checkable; a Node script verifies every claim.
The format is local-first by design. No external scripts, no network calls, no embedded secrets, no telemetry. The privacy model is the same as opening a PDF on your laptop.
Flatpack is the file format for personal software.
Baseplate is the foundation for shared software.
When a Flatpack stops being my tool and becomes our tool — a second person needs to use it, data should be stored centrally, audit history matters — it gets promoted into a Baseplate project. Two ends of the same path.
For developers
The standard, templates, and tooling live on GitHub at github.com/ConceptPending/flatpack. The spec is at SPEC.md (~475 lines, brutally specific).
Make your AI tool produce Flatpacks by default — copy one file from
agent-rules
into your project (one-line curl installs in the README).
Works with Claude Code, Cursor, Windsurf, GitHub Copilot, and any agent
that reads AGENTS.md.
Verify any Flatpack mechanically:
node tools/check-flatpack.mjs --strict. Cross-browser smoke
test runs against Chromium, Firefox, and WebKit. Handles 500,000-row
CSVs in about a second.