diff --git a/content.js b/content.js
new file mode 100644
index 0000000..00e3f94
--- /dev/null
+++ b/content.js
@@ -0,0 +1,64 @@
+const DEFAULT_REPLACEMENTS = {
+  "consultant": "conslutant",
+  "AI process engineer": "algorithm inventor"
+};
+
+function escapeRegExp(string) {
+  return string.replace(/[.*+?^${}()|[\\]\\]/g, "\\$&");
+}
+
+function replaceInTextNode(node, replacements) {
+  let text = node.nodeValue;
+  let updated = text;
+
+  for (const [search, replace] of Object.entries(replacements)) {
+    const regex = new RegExp(escapeRegExp(search), "gi");
+    updated = updated.replace(regex, replace);
+  }
+
+  if (updated !== text) {
+    node.nodeValue = updated;
+  }
+}
+
+function walk(node, replacements) {
+  if (
+    node.nodeType === Node.ELEMENT_NODE &&
+    ["SCRIPT", "STYLE", "TEXTAREA", "INPUT"].includes(node.tagName)
+  ) {
+    return;
+  }
+
+  if (node.nodeType === Node.TEXT_NODE) {
+    replaceInTextNode(node, replacements);
+    return;
+  }
+
+  for (const child of node.childNodes) {
+    walk(child, replacements);
+  }
+}
+
+async function getReplacements() {
+  return new Promise((resolve) => {
+    chrome.storage.sync.get(["replacements"], (result) => {
+      resolve(result.replacements || DEFAULT_REPLACEMENTS);
+    });
+  });
+}
+
+async function runReplacement() {
+  const replacements = await getReplacements();
+  walk(document.body, replacements);
+}
+
+runReplacement();
+
+const observer = new MutationObserver(() => {
+  runReplacement();
+});
+
+observer.observe(document.body, {
+  childList: true,
+  subtree: true
+});
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