Terms of service
The short version: SubnetKit is a free tool, use it reasonably, and we make no promises we cannot keep. Last updated 8 July 2026.
Using the site
SubnetKit is a free, browser-based subnet calculator and networking reference. By using it, you agree to these terms. There is no account to create and nothing to buy; every calculator, reference page, and guide is free to use.
What you can rely on
The calculators aim to be accurate, and the CIDR and port reference data is checked against public sources such as RFC 3021 and the IANA registries. Even so, SubnetKit is provided as is, without warranty of any kind. Do not use it as the sole basis for a decision where a mistake would be costly, such as production network changes or security configuration; always verify against your own tools and documentation.
The JSON API and embed widget
The JSON API and the embeddable widgetare free to use, including on commercial sites, without a key or rate limit. We ask that the embed widget keeps its small "Powered by SubnetKit" attribution link. We may change the shape of the API or the widget over time; breaking changes will be noted in the changelog.
Acceptable use
Do not attempt to disrupt the site, scrape it at a rate that degrades it for other visitors, or use it to generate content that is unlawful or infringes someone else's rights. We may block traffic that does this.
Advertising
SubnetKit may show ads served by third-party networks to help cover hosting costs. Ads are placed by those networks, not by SubnetKit directly, and SubnetKit does not control or endorse the specific products or services they show. See the privacy policy for how those networks may use cookies.
No liability
To the extent allowed by law, SubnetKit and its operator are not liable for damages arising from use of the site, including reliance on a calculation or reference value. Networking decisions in production environments remain your responsibility.
Changes to these terms
These terms may be updated as the site grows, for example when a new tool, the API, or advertising changes. The date above reflects the latest revision, and material changes will be noted in the changelog.
Contact
Questions about these terms can go through the contact form.