diff --git a/LICENSE.md b/LICENSE.md
new file mode 100644
index 0000000..129cdf9
--- /dev/null
+++ b/LICENSE.md
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2019 Jake Jarvis
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
index 7ca2782..0526058 100644
--- a/README.md
+++ b/README.md
@@ -1,3 +1,43 @@
-simpip.com
-=========
-A very simple IP utility that shows the user's IP address–and only the user's IP address–on a plaintext page using PHP.
\ No newline at end of file
+# 🌎 [simpip.com](https://simpip.com/)
+
+**⚡ Now powered purely by [Cloudflare Workers](https://www.cloudflare.com/products/cloudflare-workers/) — [try this code on the playground!](https://cloudflareworkers.com/#12bf2207fc352f52ebb27a041753c03d:https://tutorial.cloudflareworkers.com/)** The ancient PHP version is [archived here](https://github.com/jakejarvis/simpip/tree/php).
+
+A very, *very* "simple" web server that returns the visitor's IP address in plaintext...and **literally nothing** else. Perfect for CLI usage via `curl` or for automated tasks.
+
+This returns your IPv6 address by default, but to choose one or the other you can use [`curl`](https://curl.haxx.se/docs/manpage.html) flags:
+
+```bash
+curl simpip.com       # returns IPv6 *OR* IPv4
+curl -4 simpip.com    # returns IPv4
+curl -6 simpip.com    # returns IPv6, or fails to connect if network is incompatible
+```
+
+
+## Example
+
+In [my terminal's dotfiles](https://github.com/jakejarvis/dotfiles), I have three aliases:`ip4` and `ip6` which are self-explanatory, and simply `ip` which returns **both** addresses *iff* your network supports IPv6 — otherwise, IPv6 sliently fails and only your IPv4 address is shown.
+
+```bash
+alias ip4="curl -4 simpip.com --max-time 1 --proto-default https --silent"
+alias ip6="curl -6 simpip.com --max-time 1 --proto-default https --silent"
+alias ip="ip6; ip4"
+```
+
+Timeout is set to 1 second via `--max-time 1` (otherwise we will get stuck indefinitely trying to connect via IPv6 even if our network doesn't support it) and a secure connection preference is set using `--proto-default https`. Connection errors (particularly for IPv6) are silenced using `--silent`, so that the output of `ip` contains nothing but IP addresses, like so:
+
+```bash
+jake@macbook:~$ ip4
+1.1.1.1
+
+jake@macbook:~$ ip6
+2606:4700:4700::1111
+
+jake@macbook:~$ ip
+2606:4700:4700::1111
+1.1.1.1
+```
+
+
+## License
+
+This project is distributed under the [MIT license](LICENSE.md).
diff --git a/index.js b/index.js
new file mode 100644
index 0000000..23fb277
--- /dev/null
+++ b/index.js
@@ -0,0 +1,22 @@
+addEventListener('fetch', event => {
+  event.respondWith(handle(event.request))
+})
+
+async function handle(request) {
+  return new Response(request.headers.get("cf-connecting-ip") + "\n", {
+    status: 200,
+    statusText: "OK",
+    headers: {
+      "Content-Type": "text/plain",
+      "Content-Security-Policy": "default-src 'none';",
+      "X-Content-Type-Options": "nosniff",
+      "X-XSS-Protection": "1; mode=block",
+      "X-Frame-Options": "SAMEORIGIN",
+      "Referrer-Policy": "no-referrer",
+      "Cache-Control": "max-age=0, no-cache, no-store, must-revalidate",
+      "Pragma": "no-cache",
+      "Expires": "Wed, 11 Jan 1984 05:00:00 GMT",
+      "X-Did-You-Know": "You can visit ipv4.simpip.com or ipv6.simpip.com to get either address!"
+    }
+  });
+}
diff --git a/index.php b/index.php
deleted file mode 100644
index c123d3e..0000000
--- a/index.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php
-  header("Content-type: text/plain");
-  if(isset($_SERVER['HTTP_X_FORWARDED_FOR'])) {
-    if (($pos = strpos($_SERVER['HTTP_X_FORWARDED_FOR'], ",")) !== false) {
-      echo substr($_SERVER['HTTP_X_FORWARDED_FOR'], 0, $pos);
-    } else {
-      echo $_SERVER['HTTP_X_FORWARDED_FOR'];
-    }
-  } else {
-    echo $_SERVER['REMOTE_ADDR'];
-  }
-?>
\ No newline at end of file