Documentation

WallCab is a small, public wallpaper service built around one stable URL. You choose one or more learning interests, a built-in visual theme or optional private custom background, an iPhone size, and optionally a short personal note; the same address returns a newly composed image each UTC day.

Start in five minutes

1. Open the configurator.
2. Choose your learning interests, visual direction, device, and optional personal note.
3. Copy the generated /api/wallpaper address.
4. Follow the illustrated Apple Shortcuts guide.
5. Schedule it after 00:05 UTC so the new daily edition is ready.

How the daily edition works

The calendar date and normalized interest set determine which selected category gets today’s turn. WallCab asks an external provider for that category’s concept, validates the result, stores the accepted lesson for the active day, fetches a licensed background, and composes both into a device-specific PNG. The answer remains stable until the next UTC day.

If a provider is slow, unreachable, or returns content that cannot be safely composed, WallCab immediately uses a reviewed local fallback. The fallback catalog is continuity infrastructure—not the normal source of daily words.

Pick a guide

• API reference documents every public parameter, header, and error.
• Architecture explains content selection, rendering, and caching.
• Self-hosting covers Vercel and Cloudflare setup.
• Contributing describes the validation and review bar.
• Sources and licenses describes provenance and licensing boundaries.

Guarantees

• No account or database is required.
• A date, normalized interest set, visual choice, size, and optional note always identify the same daily edition.
• Custom uploads are optional, protected by Turnstile, stored privately, and removable without an account.
• The preview and status API disclose whether external content or the reviewed fallback was used.
• Each image includes a compact source and license credit.
• Invalid options return structured JSON rather than a surprise default.
• The renderer targets a PNG smaller than 2.2 MiB.
• A personal note is URL-visible but is never stored in the shared final-image cache.