Your files and text
- Every tool runs in your web browser. Copybooks, data files, JCL and anything else you enter are processed on your device and are never uploaded.
- The site's Content Security Policy forbids its pages from making network requests (
connect-src 'none') and from submitting forms anywhere. Even a programming mistake could not send your data out. - Nothing you enter is stored on any server, because there is no server that receives it.
What your browser keeps
- The home page lists the last few tools and code pages you opened, and remembers the tools you pinned and your colour theme.
- The copybook viewer and JCL checker remember the last text you entered, so it is still there when you come back.
- All of this lives only in your browser's local storage, on your device, and is never sent anywhere. Clearing your browser's site data for mainframekit.com removes it.
What the hosting service sees
- The site is a set of static files served by Cloudflare. Like any web host, Cloudflare handles the request for each page (for example your IP address and the page address) to deliver it and to protect against attacks. We see only totals, such as page views per day and per country, from Cloudflare's dashboard.
- No cookies, no analytics scripts, no advertising and no third-party scripts are used.
Contact
Vidyut Saha · [email protected]
Last updated 27 October 2026.