Add a privacy policy

Closes https://github.com/kytta/share2fedi/issues/26
Closes https://github.com/kytta/share2fedi/issues/27

index.html

@@ -82,6 +82,44 @@
 			</form>
 		</main>
 		<footer>
+			<details>
+				<summary>Privacy Notice</summary>
+				<p>
+					Share₂Fedi uses GoatCounter to collect usage information.
+					<a href="https://share2fedi.goatcounter.com/">
+						The usage data is public.
+					</a>
+					The following information gets collected:
+				</p>
+				<ul>
+					<li><code>User-Agent</code> header</li>
+					<li>Screen size</li>
+					<li>A hash of the IP address, User-Agent, and random number</li>
+				</ul>
+				<p>
+					This data is kept for the maximum of 90 days. None of this information
+					is shared with third parties. See
+					<a href="https://www.goatcounter.com/help/privacy"
+						>GoatCounter’s privacy policy</a
+					>
+					for more information.
+				</p>
+				<p>
+					s2f.kytta.dev is hosted on Vercel. Vercel processes IP addresses,
+					system configuration information, and other information about traffic
+					to and from s2f.kytta.dev. Vercel does not store this information nor
+					does it get shared with third parties. See
+					<a href="https://vercel.com/legal/privacy-policy#customers"
+						>Vercel's privacy policy</a
+					>
+					for more information.
+				</p>
+				<p>
+					When you click the ‘Publish’ button, you’ll get redirected to a
+					Fediverse instance you’ve specified. It may process and/or store your
+					data. Please refer to the privacy policy of the respective instance.
+				</p>
+			</details>
 			<a href="https://joinmastodon.org/">What is Mastodon?</a>
 			<a href="https://github.com/kytta/share2fedi">Share₂Fedi on GitHub</a>
 		</footer>