HydroDiagram licence terms

Last updated 12 September 2026

The short version. One purchase licences HydroDiagram on one domain, for as long as you like, for as many diagrams, applications and end users as you want. You may not sell the library itself on to somebody else. We do not guarantee it is fit for your purpose, and our liability is capped at what you paid.

1. What you are buying

A perpetual, non-exclusive, non-transferable licence to use the HydroDiagram library in software you build and operate, served from the domain you nominated at purchase. A licence key is issued to that domain.

The nominated domain and one level of subdomain — a key for example.com also covers app.example.com, but not a.b.example.com.
localhost and 127.0.0.1, so development and CI are not watermarked.
Unlimited developers, unlimited applications, unlimited end users and unlimited diagrams on that domain.
No expiry. The key does not stop working, and there is nothing to renew.

2. What it does not cover

Other domains. One key, one domain. A second site needs a second licence.
Redistribution of the library itself. You may ship HydroDiagram inside your own application; you may not sell, sublicense or publish it as a library, component or SDK for others to build on, and you may not distribute your key.
Support or updates as an entitlement. You get the version you downloaded and whatever we publish afterwards, as and when we publish it. Nothing here promises a release schedule, a fix, or a response time.

3. Honest limits of the key

HydroDiagram is JavaScript that runs in your users' browsers. The licence check runs there too, which means it can be removed by anyone willing to edit the file — this is true of every client-side diagramming library, including the ones that charge thousands of dollars per developer, and we are not going to pretend otherwise.

What the domain binding does buy is that a key lifted out of one site's bundle is useless on another. Keys are signed with a private key we hold; the library carries only the public half, so a key cannot be minted without us. Verification uses the browser's Web Crypto, which is only available in a secure context — over plain http on something other than localhost the check cannot run, and the evaluation watermark stays.

4. Refunds and reissues

Wrong domain? Reply to your receipt and we will reissue the key to the right one, at no charge. Tell us before you deploy if you can.
Changed your mind? A full refund within 30 days of purchase, for any reason, provided you stop using the key. Ask by replying to the receipt.
Moved domain permanently? One free reissue. After that, it is a new licence.

5. No warranty

HydroDiagram is provided "as is". We make no warranty that it is error-free, that it will meet your requirements, or that it is fit for any particular purpose. It draws diagrams; it does not perform engineering calculations, and nothing it renders is a substitute for a competent person's review. You are responsible for anything you publish, submit, seal or rely on.

6. Liability

To the maximum extent the law allows, our total liability arising out of or relating to this licence is limited to the amount you paid for it. We are not liable for indirect, incidental, special or consequential damages, or for lost profits, lost data or business interruption, even if we were told they were possible.

7. Termination

The licence ends if you breach these terms and do not put it right within 30 days of us telling you. On termination you must stop using the library and remove the key from your builds. Sections 5, 6 and 8 survive.

8. Governing law

These terms are governed by the laws of the State of North Carolina, United States, without regard to its conflict-of-laws rules.

9. Changes

We may revise these terms for future purchases. The terms you bought under are the ones in force on the day of purchase; we will not change the deal you already paid for.