| `API_HOST` | `https://api.scratch.mit.edu` | Hostname for API requests |
| `BACKPACK_HOST` | `https://backpack.scratch.mit.edu` | Hostname for backpack requests |
| `SENTRY_DSN` | `''` | DSN for Sentry |
| `FALLBACK` | `''` | Pass-through location for old site |
| `GA_TRACKER` | `''` | Where to log Google Analytics data |
| `NODE_ENV` | `null` | If not `production`, app acts like development |
| `PORT` | `8333` | Port for devserver (http://localhost:XXXX) |
**NOTE:** Because by default `API_HOST=https://api.scratch.mit.edu`, please be aware that, by default, you will be seeing and interacting with real data on the Scratch website.