diff --git a/README.md b/README.md
index 25d0e75..bbd6b1c 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,30 @@
-# zerotest
+# ZeroTest
 
-Test utility for 0.0.0.0 Day
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+To set up a ZeroTest instance, simply set up a Web server to host `index.html` over an unencrypted HTTP connection. (ZeroTest will not work if loaded over HTTPS, because [restrictions on mixed content](https://developer.mozilla.org/en-US/docs/Web/Security/Mixed_content) will block its requests.)
+
+A public instance is available at [https://zerotest.kj7rrv.com/](https://zerotest.kj7rrv.com/); it uses the following Nginx configuration:
+
+```nginx
+server {
+    listen 80;
+    listen [::]:80;
+    server_name zerotest.kj7rrv.com;
+
+    add_header Content-Security-Policy "connect-src 0.0.0.0:*;";
+
+    root /var/www/zerotest;
+    charset utf-8;
+}
+
+server {
+    listen 443;
+    listen [::]:443;
+    server_name zerotest.kj7rrv.com;
+
+    return 301 http://zerotest.kj7rrv.com;
+
+    include /etc/nginx/templates/ssl.tmpl;
+}
+```
+
+Note that if a [Content Security Policy](https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP) is set, it must allow `fetch` requests to all ports on `0.0.0.0`; the header in the example Nginx configuration (`connect-src 0.0.0.0:*;`) works well.
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