API Playground
Test Viikko Nro's free ISO 8601 week-number API live in your browser — no auth, no rate limit. cURL, JavaScript, PHP and Python examples below update as you change the parameters.
Request URL: /api/week/36/2026.json (redirects to /data/week/2026/36.json)
curl -L https://viikkonro.fi/api/week/36/2026.json
What happens with an invalid request?
There's no JSON error envelope — an out-of-range week, month or year still redirects, then 404s with the site's generic HTML error page, not a JSON error body. Validate parameters against the documented ranges before calling, rather than parsing the response to detect an invalid request. Full detail: Avoin data.
Usein kysyttyä
Is there a rate limit?
No — these are static files served from a CDN, not a rate-limited API.
Do I need an API key?
No authentication is required for any endpoint.
Why does this demo fetch /data/ instead of /api/?
The /api/ redirect hop itself carries no CORS header (only the final /data/ response does), so a browser fetch to /api/ can fail cross-origin from a page hosted elsewhere. Server-side code (curl, PHP, Python, Node) isn't subject to CORS at all, so either URL works there — see the code examples above, which use /api/, the documented developer-friendly path.