Email us directly
contactus@subnetmaskcalc.net

Click the address above to open your email client with a fresh message ready to send. Or copy it into your usual email tool. We read every message and reply to almost all of them — usually within 48 hours.

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Response time
~48 hours

For most messages. Bug reports and outages get priority.

What to include
  • For bugs: which tool, what you tried, what happened
  • For features: the workflow you're trying to support
  • For blog ideas: the question you wish someone answered
  • For partnerships: who you are and what you have in mind
02 / FAQ

Frequently asked.

Is this really free? What's the catch?

Yes, really free. The site runs entirely in your browser — there's almost no operating cost. We run banner ads and Google Analytics to cover hosting and keep the toolkit free for everyone. We don't sell your data. The best way to support the site is to share it with other engineers who'd find it useful.

Do you store the IPs and CIDRs I enter?

No. All calculations happen in your browser via JavaScript. We don't have a backend that receives your inputs. The only things stored locally (in your browser's storage) are lesson progress and quiz streaks, and those never leave your device.

Why doesn't the AI Assistant use GPT/Claude/etc?

By design. The AI Assistant runs entirely in your browser using a rule-based natural-language parser. This means your network design never leaves your device — which matters when you're sketching out internal infrastructure. It trades off some sophistication for full privacy and zero latency.

Can I use the generated Terraform/CloudFormation code in production?

Yes, with the usual caveat: review and test before applying. The generated code is syntactically correct and follows standard patterns, but every environment has specifics (tags, modules, naming conventions) the generator can't know about. Treat it as a starting point.

Will there ever be a paid tier?

Not for the calculators, exports, or Learn Center — those stay free. If we add anything paid in the future, it'd be optional advanced features (team workspaces, audit reports for compliance, custom branding for educators), never things that gate the core tools.

How can I support the site?

Share the link with engineers, post it in your team channel, link to it from your blog or documentation. Word of mouth is what keeps this alive.