GridStage
2026 — in active development
Why I built this
As a dancer, formations were always the part nobody wanted to handle. How do you place everyone so the stage actually looks right? Will two people run into each other halfway through a transition? Those questions bothered me every time we put a piece together. I went looking for an open-source tool and there was none — and I was not about to pay a subscription for the commercial ones. So I built GridStage.
What it is
A top-down 2D stage where you place performers, add formations along a timeline synced to the music, and preview the walk-in transitions in 2D or 3D. It exports walk-chart PDFs (one page per dancer), videos, and GIFs. Several people can edit the same piece at once — live cursors, presence, and undo that only reverts your own changes — over a CRDT, a data structure where concurrent edits merge without a central referee. The part I care most about is the vision pipeline: pause a rehearsal video on a formation, click the four stage corners once, and the app detects the dancers, maps their foot positions onto the stage floor, and drops them into the editor as a normal editable formation. All of it runs in the browser.
Where it stands
v0.8.6 · 130 commits · ~16k lines of strict-mode TypeScript in a pnpm monorepo · 24 unit-test files plus a Playwright end-to-end suite. Three ways to run it, none requiring an account: a Windows/macOS desktop app, an installable PWA that works offline on a phone, and a Docker self-host stack.
Measured, not claimed:
- 60 performers × 4 formations in a permanent end-to-end stress test — dragging stays accurate and playback holds ~57 fps (CI floor 20).
- Video → formation capture runs entirely client-side (YOLOX-nano through onnxruntime-web, WebGPU with a wasm fallback): 6 of 7 dancers recovered from a real six-dancer rehearsal photo, ~1.8 s per frame on CPU alone. Zero server cost, and no one’s rehearsal footage leaves their laptop.
Against ArrangeUs, the category leader, and the other commercial formation apps I audited before starting, these are the things they do not do at all (checked July 2026; their feature lists do move):
| Capability | GridStage | ArrangeUs & other commercial apps |
|---|---|---|
| Real-time multi-user editing | CRDT (Yjs) — live cursors, presence, per-user undo | one editor at a time, files passed around |
| Formations captured from a rehearsal video | on-device detection + homography | nothing on the market does this |
| Rehearsal-vs-plan review | per-dancer drift, C-position centering, left–right asymmetry | — |
| Transition collision warnings | Hungarian matching + sweep-line crossing detection | — |
| 3D preview | camera presets + follow-a-performer | limited |
| Video / GIF export with music | yes | limited |
| Price and licence | free, MIT, self-hostable | subscription, closed source |
The place I am clearly behind is distribution, not capability: ArrangeUs has 457k+ users and years of tutorials, GridStage has an install page.
What’s next
- Building a user community. The capability gap is closed; the distribution one is not. Demo videos and an in-app guide are already in progress, and the next step is getting the editor in front of real dance teams and cheer squads and running on their feedback — the work that decides whether GridStage stays a portfolio piece or becomes a tool people actually choreograph with.
- Accounts and cloud sync. Today a piece lives on one machine and travels as
a
.gridstagefile. This is the largest remaining gap against commercial tools, and the one architectural decision I still owe the project — self-host or a hosted backend. - Full rehearsal-vs-plan deviation report. The first cut compares one paused frame against the plan. Scanning a whole rehearsal into a per-formation error timeline is the version that closes the plan → rehearse → correct loop, and it is the hardest part for anyone to copy.
- Stage lighting and cue sheets. Colored lights on the 2D stage and a 3D wash, cues on the timeline, exported as a printable cue sheet — the other half of what a stage manager actually needs.
- Plugins and a community template library, so formation libraries can grow without me writing every one of them.
