Cookie policy

This page lists every cookie and every item the website keeps in your browser, why it is there, how long it lasts, and how you control it. How the website handles personal data in general is in the privacy policy.

Who is responsible

Cuong Thach, who runs https://cuongthach.com. For any question about cookies or personal data, write to cuong@cuongthach.com. The website has no separate Data Protection Officer; that address answers every privacy question.

Legal basis

• Necessary cookies need no consent (the exemption in ePrivacy Directive Art. 5(3)). The basis is the legitimate interest in running and protecting the website (GDPR Art. 6(1)(f)).
• Analytics cookies and tools run only with your prior consent (ePrivacy Directive Art. 5(3), GDPR Art. 6(1)(a)) on the English pages, and on every page for readers in Europe.
• The Vietnamese pages, made for readers in Vietnam, ask Cloudflare which country you are in (through the site’s own /cdn-cgi/trace address; nothing is stored). Readers in the EU, the EEA, the UK, Switzerland, or of unknown country see the cookie box, and nothing runs before they accept. Readers anywhere else are not asked: analytics start when the page opens, unless you already chose Reject or your browser sends Global Privacy Control. This check relies on your IP address, so it has limits: if you are in Europe but use a VPN or a network that exits in another country, the website may not notice. You can still turn analytics off with the Cookie settings button, or switch on Global Privacy Control in your browser. The Cookie settings button in the sidebar of the policy pages still opens the box so you can turn it off.
• The website treats a Global Privacy Control signal from your browser as a refusal.

Necessary cookies

Cookie	Provider	Purpose	Duration
cf_clearance	Cloudflare	Remembers that your browser passed Cloudflare’s security check, so it is not checked again on every page	One year
lang	CuongThach	Remembers the language you picked; set only when you switch language	One year
Sign-in cookies (__Secure-better-auth.*)	CuongThach	Keep you signed in after you sign in with Google, and stop forged sign-ins while you go to Google	60 days, or until you sign out
nl	CuongThach	Remembers that you subscribed to the newsletter. Holds the edition language (vi or en), or 1 if you subscribed before 4 November 2026; no name or email. Set only when you subscribe	One year, or until you unsubscribe
wl	CuongThach	Remembers that you saved a waitlist spot and the list code; set only when you join	One year

Analytics cookies

Set only while analytics run (see Legal basis). All of them are deleted when you withdraw your consent.

Cookie	Provider	Purpose	Duration
cf_zaraz_client	Cloudflare Zaraz	Keeps technical details so Zaraz sends each visit to the right analytics tools	One year
cfz_google-analytics_v4	Cloudflare Zaraz, for Google Analytics 4	A random code, so a person who comes back counts as one person	One year
cfzs_google-analytics_v4	Cloudflare Zaraz, for Google Analytics 4	Marks one reading session	Until you close your browser

Browser storage

These items stay on your device and are never sent anywhere.

Item	Where	Purpose	Duration
consent	localStorage	Your cookie choice (analytics or none) and its date, so the box does not ask on every page	180 days
Light or dark mode (ui-mode on the docs)	localStorage	Remembers the look you picked	Until you clear it
Audio position	localStorage	Picks up where you stopped listening	Until you clear it
Docs sidebar state	sessionStorage	Keeps open groups open as you move between pages	Until you close the tab

Analytics tools without cookies

These two tools set no cookies, but your browser sends data to their servers, so they follow the same rules as analytics cookies.

• Cloudflare Web Analytics (Cloudflare, Inc.; loaded from static.cloudflareinsights.com, sends to cloudflareinsights.com): counts visits and how fast pages load.
• Ahrefs Web Analytics (Ahrefs Pte. Ltd., Singapore): switched on by Cloudflare Zaraz, your browser loads its script from analytics.ahrefs.com and sends the visit and where it came from to Ahrefs.

Third parties that receive data

Each service below gets at least your IP address and browser type when it is contacted.

• Cloudflare, Inc.: hosting, security, spam checks (Turnstile), Zaraz and Cloudflare Web Analytics. Policy: https://www.cloudflare.com/privacypolicy/ (opens in a new tab)

• Google Ireland Limited and Google LLC: Google Analytics 4 through Zaraz (only while analytics run), and Google sign-in (when you choose it). Policy: https://policies.google.com/privacy (opens in a new tab)

• Ahrefs Pte. Ltd.: Ahrefs Web Analytics (only while analytics run). Policy: https://ahrefs.com/legal/privacy-policy (opens in a new tab)

• VerifiedDR: the VerifiedDR score image in the proof badge at the bottom of the page. It loads straight from verifieddr.com when you scroll to the bottom of a page, even before you choose on the cookie box. VerifiedDR needs to see its own image to confirm the website belongs to Cuong, and that fair interest is the basis. The image sets no cookie and stores nothing on your device. Policy: https://verifieddr.com/privacy (opens in a new tab)

The other images in the proof badge (VerifiedDR’s visit count, WebScore, GDPR Fix) are saved and served from cuongthach.com itself, so those services get none of your data unless you click it to open their page.

Some providers handle data outside the European Union; the transfer mechanism of each one is in the privacy policy.

How long data is kept

• Cookies: see the Duration column in the tables above.
• Google Analytics visit data: for the period set in the account (2 months by default).
• Cloudflare Web Analytics and Ahrefs: Cloudflare Web Analytics keeps the full visit data for 7 days, then only a summary, which the dashboard shows for 6 months. Ahrefs stores no IP addresses, replaces and deletes its counting code every 24 hours, and does not publish how long it keeps totals; you can ask Ahrefs at privacy@ahrefs.com.

How to change or withdraw your consent at any time

On the cookie box, Reject all and Accept all are equally easy to press; Customize lets you switch Analytics on or off by itself. To change your mind at any time, press the Cookie settings button in the sidebar of the policy pages (or click here), then choose Reject all, or turn Analytics off and press Save choices. The website deletes the analytics cookies, reloads the page, and stops loading the analytics tools. Withdrawing does not change what was processed before. You can also delete cookies in your browser settings.

Your rights under the GDPR

You have the right of access, rectification, erasure, restriction, data portability and objection, the right to withdraw consent at any time, and the right to complain to a supervisory authority, for example in the European country where you live or work. Send your request to cuong@cuongthach.com; we reply within one month. Details are in the privacy policy.

Changes to this policy

This page is updated before the website adds any new tracking tool, with the date at the top.