Diagrammo is a diagram-as-code tool by Demian Neidetcher (VP at MLB), built with Claude Code. Diagrams are written in plain-text .dgmo files that live in git, render in the browser or a Mac app, and don't drift like screenshot-based diagrams.

Do I need an account to use Diagrammo?

No. The browser version at online.diagrammo.app requires no account. Files stay local in browser storage. There's also a Mac app available.

What is the .dgmo file format?

A simple human-readable DSL. Boxes-and-lines syntax: declare boxes, draw arrows with ->, group with brackets, add descriptions with |. The whole format is teachable in 30 seconds by paste-and-render.

Why diagram-as-code instead of Lucidchart or draw.io?

Diagrams in WYSIWYG tools go stale. The system changes, the screenshot is now a lie. Diagram-as-code lives in version control — when the system changes, you edit text the same way you edit code, so the diagram and the code drift together, not apart.

Who built Diagrammo and why?

Demian Neidetcher, a VP at Major League Baseball, built Diagrammo on the side using Claude Code. It is an existence proof of single-operator agentic-engineering — frontier-tier production tools shipped by individuals with taste on top of the AI leverage layer.

OPERATOR ONBOARDING · CLAUDE-CODE TOOL · 2026-04-30

Diagrammo for operators — your first diagram in 30 seconds

Q: How do I render my first Diagrammo diagram?

Open online.diagrammo.app, paste a boxes-and-lines starter snippet (for example, the universal business loop: Capture -> Generate -> Publish -> Convert -> Capture), watch it render instantly, then edit the box names to match your actual business stages.

Diagrammo is diagram-as-code. .dgmo files. Browser or Mac. Git-friendly. No WYSIWYG drift. This page is the operator-onboarding layer the README doesn't ship — paste, render, ship.

Tool: Diagrammo by Demian Neidetcher · open in browser →

PJ Zonis Single operator · SideGuy Solutions · Encinitas · Ships the operator-translation layer for tools like this — about →

TL;DR: Diagrammo is a diagram-as-code tool by Demian Neidetcher (VP at MLB, built with Claude Code). Diagrams live in plain-text .dgmo files you can version in git, paste anywhere, and render in the browser or Mac app — no WYSIWYG, no SaaS lock-in, no screenshots that go stale the moment your system changes. The README is built for builders. This page is built for operators: paste one snippet, see your business loop render in 30 seconds, edit it in plain text forever after.

Why operators should care (60-second version)

Most diagrams die. You build one in Lucidchart, screenshot it into a doc, the system changes, the screenshot is now a lie. Six months later nobody trusts any diagram in your repo because half of them are wrong.

Diagram-as-code fixes that. The diagram source is a text file. It lives in git next to your code. When the system changes, you edit the text — same way you edit code. The diagram and the code drift together, not apart.

Diagrammo is the cleanest implementation I've seen. The DSL is human-readable on first sight. You don't need to learn anything to start.

Your first diagram in 4 steps (30 seconds)

1Open the editor

Go to online.diagrammo.app. No account. Runs in your browser. Files stay local in browser storage.

2Paste this starter snippet into the editor

This is the universal business loop — capture, generate, publish, convert, repeat. Every business runs some version of this.

boxes-and-lines
direction TD
Capture -> Generate
Generate -> Publish
Publish -> Convert
Convert -> Capture
Capture | description: Where leads/inputs come in
Generate | description: Where you build the artifact
Publish | description: Where it lives publicly
Convert | description: Where revenue happens

3Watch it render instantly

Right pane updates as you type. No build step. No "render" button. The diagram IS the source.

4Edit it for YOUR business

Replace "Capture / Generate / Publish / Convert" with your actual stages. Add boxes. Add arrows. Save the .dgmo file. Drop it in your repo. Done — your business loop now lives in version control.

3 more snippets to try (paste-ready)

Use case 1 — User flow with decision branches

Show how a visitor moves through your site or product. Use grouping [brackets] for clusters of related boxes.

boxes-and-lines
direction LR
Visitor -> Landing Page
Landing Page -> Pricing
Landing Page -> Free Tool
Pricing -> Checkout
Free Tool -> Email Capture
Email Capture -> Nurture Sequence
Checkout -> Customer
Nurture Sequence -> Customer

Use case 2 — Comparison chart (no flow, just structure)

For positioning docs, product comparisons, before/after framing. Brackets group items as siblings under a header.

boxes-and-lines
direction TD
[Old Way]
  Lucidchart
  Screenshots in Notion
  Diagrams go stale
[New Way]
  Diagram-as-code
  .dgmo file in git
  Diagram and code drift together

Use case 3 — Service architecture

Show how systems talk to each other. Useful for onboarding new engineers or explaining your stack to a non-technical stakeholder.

boxes-and-lines
direction LR
Browser -> CDN
CDN -> Static Site
Browser -> API
API -> Database
API -> Cache
Cache -> Database
Static Site | description: Cached at edge
API | description: Single backend service
Database | description: Source of truth

Why this exists (and why I built this page)

Karpathy named the era at AI Ascent 2026: Software 3.0 = LLMs as the new programming primitive. Vibe coding raised the floor; agentic engineering raises the ceiling. Single operators with taste shipping production tools on top of the leverage layer.

Diagrammo is exactly that — a VP at MLB, on the side, shipped a diagram-as-code tool with Claude Code that competes with VC-backed tools. That's the existence proof.

But builder-built tools have one gap: the README is for builders. Operators bounce. So this page is the bridge — paste-ready snippets, real use cases, and a 30-second path from "what is this" to "I just shipped my first diagram."

That's the whole SideGuy thesis: I ship the operator-translation layer for tools that nerds build but operators can't figure out how to use.

Built by: Demian Neidetcher — VP at Major League Baseball, shipped Diagrammo with Claude Code. The kind of single-operator-meets-frontier-tooling proof point this whole era is about.

What operators get from Diagrammo

Diagrams that don't go stale — they live in git, drift with the code
Plain-text source you can paste anywhere, edit anywhere, version forever
No SaaS lock-in, no account, no monthly fee — files stay local
30-second onboarding (you just did it) vs 30-minute Lucidchart tutorials
Existence proof that single operators ship frontier-quality tools now

Want this kind of operator-translation page for YOUR tool?

If you're a builder shipping something gorgeous that operators can't figure out — that's what SideGuy ships. One text usually surfaces what's worth building first.

📲 Text PJ · 858-461-8054 See offer tiers →

— PJ · SideGuy Solutions · Encinitas · The operator-translation layer for tools like this