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Frequently asked questions

Short answers to the things people ask most. Each links to the full detail.

Building​

Do I need to know how to code?​

No. You can describe an app in plain English and have an AI assistant write both files for you — see Build with AI. You'll still preview it and tweak it, but you don't have to write code from scratch.

What language are apps written in?​

Starlark, a small, sandboxed dialect that looks like Python but isn't. A handful of Python things don't exist in it (no import, no while, no try/except), which trips up hand-written and AI-written code alike — see Starlark vs Python.

Can I animate or scroll?​

Not yet. Apps render as still frames today: each refresh draws one picture, and the panel shows it until the next refresh. There's no per-frame animation or scrolling marquee. It's on the roadmap and we'll prioritize it based on demand — if you want it, let us know. For now, design for a still image and let the refresh timer show new data.

How often does my app update?​

However often you set refresh: (in seconds) in manifest.yaml. 60 is the practical floor; 300 (5 min) is a good default; use 3600 for hourly data. The panel re-renders on that timer. See Handling time.

Can my app remember data between updates?​

No. Every render starts fresh and knows only its inputs and ctx.now — there's no storage that carries across refreshes. If you need state, keep it in the data source you fetch from.

How do I add or change a setting after I've made the app?​

In Studio, the settings card has + Add setting, or edit manifest.yaml directly. Re-attaching a setting your code stopped reading is a one-liner. See Inputs & configuration.

Drawing and text​

Why is my text invisible?​

The three usual causes, in order:

  1. It's lowercase. The bitmap fonts have no lowercase letters, so lowercase draws nothing. Call .upper() on everything. (gdn check warns about this.)
  2. It's off-canvas. The panel is 32 px tall; anything drawn past the edges is clipped. Check your y is 0–31 and x is within the panel width.
  3. It's the same color as the background — e.g. black text after c.clear().

More in Troubleshooting → it runs but looks wrong.

Can I use lowercase letters?​

No — there are no lowercase glyphs. Write in caps and .upper() anything from an input or a feed.

Live data and APIs​

How do I fetch live data?​

http.get(url), which returns a dict you read with resp["status_code"] and resp["json"]. Full details and the failure-handling pattern in HTTP requests.

Where do I find APIs to use?​

A great catalog of free ones is the community-maintained public-apis/public-apis list. When you pick one, favor APIs that:

  • return JSON (easiest to read with resp["json"]),
  • answer fast — each request has a 4-second timeout,
  • need no key, or a simple key — and if it needs one, collect it as an api-key input.

Why doesn't my API key work?​

Almost always because it was collected as a free-text input. A key must use app_input_type: api-key — that's what encrypts it and routes it correctly. Also, an api-key key name can't contain _ or - (use apikey). See API keys.

My app fetched data before, then stopped — why?​

Usually a limit: an app may make 8 uncached requests per render, and any request slower than 4 seconds comes back as status_code 0 rather than hanging the panel. A flaky or rate-limited API shows up exactly this way — always draw a fallback when status_code != 200.

Why does my clock show the wrong time?​

ctx.now is UTC, not the viewer's local time — the panel doesn't know where it's hanging. Convert with a UTC-offset input or a time API. See Handling time.

Publishing and limits​

How do I publish my app?​

Validate it, then submit a pull request — from Studio or gdn submit. See Publish an app.

Can I keep an app private?​

Yes — private apps run just for you without going through the public catalog.

What are the size and speed limits?​

Panels are up to 384 px wide and always 32 px tall; a render has time, request, and draw-op caps. They're all collected in Limits & performance.

I got an error I don't understand — where do I look?​

Troubleshooting maps the common error messages to what they mean and how to fix them.