Privacy policy
Updated 2026-10-19
Who we are
SegAudit LLC, a Wisconsin limited liability company, makes NetDiagrams and decides how the personal data described here is used. Mailing address: SegAudit LLC, c/o Northwest Registered Agent, 2800 E. Enterprise Ave, Ste 333, Appleton, WI 54913, USA. Privacy questions and requests: hello (at) netdiagrams.com.
This website
The site sets no cookies and runs no analytics or advertising scripts. Fonts are served from this site, not from a third party. Our host, Cloudflare, keeps standard server logs, including IP addresses, for security, for a limited period.
The free chapters, quiz and worksheets need no sign-up.
When you buy a book
Paddle (Paddle.com Market Limited) sells the books as our merchant of record. Paddle collects your name, email, billing country and payment details, takes the payment and issues the invoice under its own privacy notice. Card numbers never reach us.
From Paddle we receive your email address, order number and what you bought. We use them to email your download link and a free link to each new edition of a book you bought, to stamp each book file with your email and order number, and to answer you. We keep:
- the order: email address, order number, product, and when the download link expires
- each file we stamped for you, and its fingerprint (a SHA-256 hash), so a copy found online can be traced back to its order
- when each file was downloaded
Download links are stored only as a hash.
When you email us, ask for a refund or sign up
If you write to us or use the refund form, we keep what you send: your email, order number, and any reason or note you give. The refund reason is optional and doesn't affect your refund. If you ask for the free PDF or for news of new books, we keep your email address, which page you signed up on, and when you confirmed. We send one email asking you to confirm, and nothing else until you do. Every email has an unsubscribe link. Unsubscribing deletes your signup and keeps only your address on a do-not-email list, so new-edition emails stop too. Signup forms use Cloudflare Turnstile to block automated signups; it checks your browser without setting advertising cookies.
How long we keep it
| Data | Kept for |
|---|---|
| Orders, stamped files, file fingerprints and download records | 7 years after the order |
| Emails and refund requests | 3 years |
| Email signups | Until you unsubscribe |
| Server logs at Cloudflare | Cloudflare's standard retention |
Legal bases (EEA, UK and Switzerland)
| Use | Legal basis |
|---|---|
| Delivering your order, support and refunds | Performing our contract with you |
| Tax and accounting records | Legal obligation |
| Stamping files and tracing leaked copies, server logs | Our legitimate interest in protecting our books and running a secure service |
| Email signups | Your consent, which you can withdraw with the unsubscribe link |
We are in the United States and so are most of our vendors, so personal data is processed there; Paddle is in the United Kingdom. Where the law requires it, transfers use the European Commission's standard contractual clauses or another lawful mechanism.
Vendors
- Paddle: checkout, payment, tax, invoices and refunds.
- Cloudflare: hosting, file storage, the order and signup database, sending emails, and the Turnstile check on signup forms.
We do not sell or share personal data, use it for targeted advertising, or profile you. If your browser sends Global Privacy Control or Do Not Track, we treat it as an opt-out of any sale or sharing.
Your rights
Wherever you live, you can ask for a copy of your personal data, a correction, or deletion, and object to its use. Email hello (at) netdiagrams.com from the address the data is about. We answer within 45 days, may first confirm the request comes from you, and never treat you differently for asking. Deleting an order record also deletes our copies of your stamped files; records we must keep for tax are kept by Paddle. If we decline a request, we say why, and you can appeal by replying. EU and UK residents can also complain to their data protection regulator.
Changes
The date at the top shows when this policy last changed. We won't use personal data we already hold in a materially different way without telling you first.