diff --git a/background/openusercss-api.js b/background/openusercss-api.js
new file mode 100644
index 00000000..f780d025
--- /dev/null
+++ b/background/openusercss-api.js
@@ -0,0 +1,106 @@
+'use strict';
+
+// begin:nanographql - Tiny graphQL client library
+// License: MIT
+
+const getOpname = /(query|mutation) ?([\w\d-_]+)? ?\(.*?\)? \{/;
+const gql = str => {
+  str = Array.isArray(str) ? str.join('') : str;
+  const name = getOpname.exec(str);
+  return function (variables) {
+    const data = {query: str};
+    if (variables) data.variables = JSON.stringify(variables);
+    if (name && name.length) {
+      const operationName = name[2];
+      if (operationName) data.operationName = name[2];
+    }
+    return JSON.stringify(data);
+  };
+};
+
+// end:nanographql
+
+const api = 'https://api.openusercss.org';
+const doQuery = ({id}, queryString) => new Promise((resolve, reject) => {
+  const query = gql(queryString);
+
+  fetch(api, {
+    'method': 'POST',
+    'headers': new Headers({
+      'Content-Type': 'application/json'
+    }),
+    'body': query({
+      id
+    })
+  })
+  .then(res => {
+    res.json()
+    .then(response => {
+      if (response.errors) {
+        reject(new Error(JSON.stringify(response.errors)));
+      }
+      resolve(response);
+    });
+  })
+  .catch(reject);
+});
+
+window.API_METHODS = Object.assign(window.API_METHODS || {}, {
+  /**
+   *   This function can be used to retrieve a theme object from the
+   *   GraphQL API, set above
+   *
+   *   Example:
+   *   chrome.runtime.sendMessage({
+   *     'method': 'oucThemeById',
+   *     'id':     '5a2f819f7c57c751001b49df'
+   *   }, console.log);
+   *
+   *   @param {ID} $0.id MongoDB style ID
+   *   @returns {Promise.<{data: object}>} The GraphQL result with the `theme` object
+   */
+
+  'oucThemeById': params => doQuery(params, `
+    query($id: ID!) {
+      theme(id: $id) {
+        _id
+        title
+        description
+        createdAt
+        lastUpdate
+        version
+        screenshots
+        user {
+          _id
+          displayname
+        }
+      }
+    }
+  `),
+
+  /**
+   *   This function can be used to retrieve a user object from the
+   *   GraphQL API, set above
+   *
+   *   Example:
+   *   chrome.runtime.sendMessage({
+   *     'method': 'oucUserById',
+   *     'id':     '5a2f0361ba666f0b00b9c827'
+   *   }, console.log);
+   *
+   *   @param {ID} $0.id MongoDB style ID
+   *   @returns {Promise.<{data: object}>} The GraphQL result with the `user` object
+   */
+
+  'oucUserById': params => doQuery(params, `
+    query($id: ID!) {
+      user(id: $id) {
+        _id
+        displayname
+        avatarUrl
+        smallAvatarUrl
+        bio
+      }
+    }
+  `),
+});
diff --git a/manifest.json b/manifest.json
index baa0a7c9..8cffdff2 100644
--- a/manifest.json
+++ b/manifest.json
@@ -34,6 +34,7 @@
       "background/search-db.js",
       "background/update.js",
       "background/refresh-all-tabs.js",
+      "background/openusercss-api.js",
       "vendor/node-semver/semver.js",
       "vendor-overwrites/colorpicker/colorconverter.js"
     ]