KWANTIL · Band Checker

Does the band or limit deliver what it states?

Drop a CSV of forecasts, outcomes and a stated band. In a few seconds you see whether the pair is a forecast and its own outcome, and whether the band covers as often as it says, overall, by delivery slot and by month. It is the first two sections of the Specimen audit, run by your browser on your file.

It is not only for energy. A file with one value per row and a stated limit works too: a daily P&L against a VaR, or measured parts against a tolerance. The page then reports how often the value stayed inside the limit, with an interval, and where the misses fall.

Your file stays on your computer. You can check.

This page is one HTML file with its code inside it. Your browser reads your file and does the arithmetic; nothing is uploaded. The page’s security policy tells your browser to refuse any request the page tries to make to a server: fetches, uploads, beacons, form posts, images and scripts from anywhere. It does not stop you following a link yourself, which is why the only links here are ones you click. The page stores nothing on your computer: no cookies, no local storage. The site is served through Cloudflare, which, like any web host, sees that the page was loaded and from which address; it cannot see what you do with the page afterwards, because nothing is sent.

  1. Offline test. Load this page, disconnect from the network, then drop your file. The result still appears, so the work cannot be happening on a server. Close the tab before you reconnect.
  2. Network tab. Open your browser’s developer tools (F12), choose Network, then drop your file. No request appears. The policy is in the page’s source, in the Content-Security-Policy meta tag, and in the response headers when the page is served from kwantil.com.
  3. Read it. Save the page and read it; everything that runs is in one script block. The policy lets exactly one script run, pinned by its hash. Your browser computed that script’s hash just now: running: computing…pinned by the policy: result: The whole file’s SHA-256 is published at kwantil.com/check/SHA256SUMS.txt, next to the page. Compare it with sha256sum (macOS and Linux) or certutil -hashfile index.html SHA256 (Windows). The method is a port of the published audit_specimen.py (SHA-256 ), and the test vector below reproduces the Specimen’s published numbers exactly.

Save this page to run it offline. The saved file is the same bytes as the one served, so its hash matches the published one, and it works with no connection at all.

Your file

No file to hand? 13 months of DE-LU day-ahead load forecasts from ENTSO-E, bundled inside this page.

Not in energy? Two synthetic samples bundled inside this page: 750 days of P&L against a 99% VaR, and 480 parts against a tolerance. They are illustrations, not anyone’s data.