diff --git a/.dockerignore b/.dockerignore
index b2a9091..a9f7bc4 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -1,5 +1,4 @@
 # Exclude a bunch of stuff which can make the build context a larger than it needs to be
-.git/
 tests/
 build/
 lib/
diff --git a/README.md b/README.md
index 4bae8a4..6af447f 100644
--- a/README.md
+++ b/README.md
@@ -4,7 +4,7 @@
 
 This project is built using [react-admin](https://marmelab.com/react-admin/).
 
-It needs at least Synapse v1.14.0 for all functions to work as expected!
+It needs at least Synapse v1.15.0 for all functions to work as expected!
 
 ## Step-By-Step install:
 
@@ -29,3 +29,8 @@ Steps for 2):
 ## Screenshots
 
 ![Screenshots](./screenshots.jpg)
+
+## Development
+
+- Use `yarn test` to run all style, lint and unit tests
+- Use `yarn fix` to fix the coding style
diff --git a/package.json b/package.json
index 2bb3cd4..09db13f 100644
--- a/package.json
+++ b/package.json
@@ -18,6 +18,7 @@
     "eslint": "^6.8.0",
     "eslint-config-prettier": "^6.10.1",
     "eslint-plugin-prettier": "^3.1.2",
+    "jest-fetch-mock": "^3.0.3",
     "prettier": "^2.0.0"
   },
   "dependencies": {
diff --git a/src/App.js b/src/App.js
index b3c40c3..a7fc125 100644
--- a/src/App.js
+++ b/src/App.js
@@ -37,6 +37,7 @@ const App = () => (
     />
     <Resource name="rooms" list={RoomList} show={RoomShow} icon={RoomIcon} />
     <Resource name="connections" />
+    <Resource name="devices" />
     <Resource name="servernotices" />
   </Admin>
 );
diff --git a/src/components/devices.js b/src/components/devices.js
new file mode 100644
index 0000000..ee9292c
--- /dev/null
+++ b/src/components/devices.js
@@ -0,0 +1,89 @@
+import React, { Fragment, useState } from "react";
+import {
+  Button,
+  useMutation,
+  useNotify,
+  Confirm,
+  useRefresh,
+} from "react-admin";
+import ActionDelete from "@material-ui/icons/Delete";
+import { makeStyles } from "@material-ui/core/styles";
+import { fade } from "@material-ui/core/styles/colorManipulator";
+import classnames from "classnames";
+
+const useStyles = makeStyles(
+  theme => ({
+    deleteButton: {
+      color: theme.palette.error.main,
+      "&:hover": {
+        backgroundColor: fade(theme.palette.error.main, 0.12),
+        // Reset on mouse devices
+        "@media (hover: none)": {
+          backgroundColor: "transparent",
+        },
+      },
+    },
+  }),
+  { name: "RaDeleteDeviceButton" }
+);
+
+export const DeviceRemoveButton = props => {
+  const { record } = props;
+  const classes = useStyles(props);
+  const [open, setOpen] = useState(false);
+  const refresh = useRefresh();
+  const notify = useNotify();
+
+  const [removeDevice, { loading }] = useMutation();
+
+  if (!record) return null;
+
+  const handleClick = () => setOpen(true);
+  const handleDialogClose = () => setOpen(false);
+
+  const handleConfirm = () => {
+    removeDevice(
+      {
+        type: "delete",
+        resource: "devices",
+        payload: {
+          id: record.id,
+          user_id: record.user_id,
+        },
+      },
+      {
+        onSuccess: () => {
+          notify("resources.devices.action.erase.success");
+          refresh();
+        },
+        onFailure: () =>
+          notify("resources.devices.action.erase.failure", "error"),
+      }
+    );
+    setOpen(false);
+  };
+
+  return (
+    <Fragment>
+      <Button
+        label="ra.action.remove"
+        onClick={handleClick}
+        className={classnames("ra-delete-button", classes.deleteButton)}
+      >
+        <ActionDelete />
+      </Button>
+      <Confirm
+        isOpen={open}
+        loading={loading}
+        onConfirm={handleConfirm}
+        onClose={handleDialogClose}
+        title="resources.devices.action.erase.title"
+        content="resources.devices.action.erase.content"
+        translateOptions={{
+          id: record.id,
+          name: record.display_name ? record.display_name : record.id,
+        }}
+      />
+    </Fragment>
+  );
+};
diff --git a/src/components/users.js b/src/components/users.js
index c65cd12..a6889b2 100644
--- a/src/components/users.js
+++ b/src/components/users.js
@@ -2,6 +2,7 @@ import React, { cloneElement, Fragment } from "react";
 import Avatar from "@material-ui/core/Avatar";
 import PersonPinIcon from "@material-ui/icons/PersonPin";
 import ContactMailIcon from "@material-ui/icons/ContactMail";
+import DevicesIcon from "@material-ui/icons/Devices";
 import SettingsInputComponentIcon from "@material-ui/icons/SettingsInputComponent";
 import {
   ArrayInput,
@@ -23,6 +24,7 @@ import {
   TextField,
   TextInput,
   ReferenceField,
+  ReferenceManyField,
   SelectInput,
   BulkDeleteButton,
   DeleteButton,
@@ -36,6 +38,7 @@ import {
   sanitizeListRestProps,
 } from "react-admin";
 import { ServerNoticeButton, ServerNoticeBulkButton } from "./ServerNotices";
+import { DeviceRemoveButton } from "./devices";
 import { makeStyles } from "@material-ui/core/styles";
 
 const useStyles = makeStyles({
@@ -205,6 +208,7 @@ const UserTitle = ({ record }) => {
 };
 export const UserEdit = props => {
   const classes = useStyles();
+  const translate = useTranslate();
   return (
     <Edit {...props} title={<UserTitle />}>
       <TabbedForm toolbar={<UserEditToolbar />}>
@@ -254,6 +258,37 @@ export const UserEdit = props => {
             </SimpleFormIterator>
           </ArrayInput>
         </FormTab>
+        <FormTab
+          label={translate("resources.devices.name", { smart_count: 2 })}
+          icon={<DevicesIcon />}
+          path="devices"
+        >
+          <ReferenceManyField
+            reference="devices"
+            target="user_id"
+            addLabel={false}
+          >
+            <Datagrid style={{ width: "100%" }}>
+              <TextField source="device_id" sortable={false} />
+              <TextField source="display_name" sortable={false} />
+              <TextField source="last_seen_ip" sortable={false} />
+              <DateField
+                source="last_seen_ts"
+                showTime
+                options={{
+                  year: "numeric",
+                  month: "2-digit",
+                  day: "2-digit",
+                  hour: "2-digit",
+                  minute: "2-digit",
+                  second: "2-digit",
+                }}
+                sortable={false}
+              />
+              <DeviceRemoveButton />
+            </Datagrid>
+          </ReferenceManyField>
+        </FormTab>
         <FormTab
           label="resources.connections.name"
           icon={<SettingsInputComponentIcon />}
diff --git a/src/i18n/de.js b/src/i18n/de.js
index 560e310..0243041 100644
--- a/src/i18n/de.js
+++ b/src/i18n/de.js
@@ -37,7 +37,7 @@ export default {
         id: "Benutzer-ID",
         name: "Name",
         is_guest: "Gast",
-        admin: "Admin",
+        admin: "Server Administrator",
         deactivated: "Deaktiviert",
         guests: "Zeige Gäste",
         show_deactivated: "Zeige deaktivierte Benutzer",
@@ -51,6 +51,11 @@ export default {
         address: "Adresse",
         creation_ts_ms: "Zeitpunkt der Erstellung",
         consent_version: "Zugestimmte Geschäftsbedingungen",
+        // Devices:
+        device_id: "Geräte-ID",
+        display_name: "Gerätename",
+        last_seen_ts: "Zeitstempel",
+        last_seen_ip: "IP-Adresse",
       },
       helper: {
         deactivate: "Deaktivierte Nutzer können nicht wieder aktiviert werden.",
@@ -107,6 +112,17 @@ export default {
         user_agent: "User Agent",
       },
     },
+    devices: {
+      name: "Gerät |||| Geräte",
+      action: {
+        erase: {
+          title: "Entferne %{id}",
+          content: 'Möchten Sie das Gerät "%{name}" wirklich entfernen?',
+          success: "Gerät erfolgreich entfernt.",
+          failure: "Beim Entfernen ist ein Fehler aufgetreten.",
+        },
+      },
+    },
     servernotices: {
       name: "Serverbenachrichtigungen",
       send: "Servernachricht versenden",
diff --git a/src/i18n/en.js b/src/i18n/en.js
index 12ba1ae..f6501c9 100644
--- a/src/i18n/en.js
+++ b/src/i18n/en.js
@@ -35,7 +35,7 @@ export default {
         id: "User-ID",
         name: "Name",
         is_guest: "Guest",
-        admin: "Admin",
+        admin: "Server Administrator",
         deactivated: "Deactivated",
         guests: "Show guests",
         show_deactivated: "Show deactivated users",
@@ -49,6 +49,11 @@ export default {
         address: "Address",
         creation_ts_ms: "Creation timestamp",
         consent_version: "Consent version",
+        // Devices:
+        device_id: "Device-ID",
+        display_name: "Device name",
+        last_seen_ts: "Timestamp",
+        last_seen_ip: "IP address",
       },
       helper: {
         deactivate: "Deactivated users cannot be reactivated",
@@ -105,6 +110,17 @@ export default {
         user_agent: "User agent",
       },
     },
+    devices: {
+      name: "Device |||| Devices",
+      action: {
+        erase: {
+          title: "Removing %{id}",
+          content: 'Are you sure you want to remove the device "%{name}"?',
+          success: "Device successfully removed.",
+          failure: "An error has occurred.",
+        },
+      },
+    },
     servernotices: {
       name: "Server Notices",
       send: "Send server notices",
diff --git a/src/setupTests.js b/src/setupTests.js
index 6f413a4..b1a6b6d 100644
--- a/src/setupTests.js
+++ b/src/setupTests.js
@@ -1,4 +1,6 @@
 import { configure } from "enzyme";
 import Adapter from "enzyme-adapter-react-16";
+import fetchMock from "jest-fetch-mock";
 
 configure({ adapter: new Adapter() });
+fetchMock.enableMocks();
diff --git a/src/synapse/dataProvider.js b/src/synapse/dataProvider.js
index cebc413..d4c8bcd 100644
--- a/src/synapse/dataProvider.js
+++ b/src/synapse/dataProvider.js
@@ -45,8 +45,8 @@ const resourceMap = {
       body: data,
       method: "PUT",
     }),
-    delete: id => ({
-      endpoint: `/_synapse/admin/v1/deactivate/${id}`,
+    delete: params => ({
+      endpoint: `/_synapse/admin/v1/deactivate/${params.id}`,
       body: { erase: true },
       method: "POST",
     }),
@@ -67,6 +67,19 @@ const resourceMap = {
       return json.total_rooms;
     },
   },
+  devices: {
+    map: d => ({
+      ...d,
+      id: d.device_id,
+    }),
+    data: "devices",
+    reference: id => ({
+      endpoint: `/_synapse/admin/v2/users/${id}/devices`,
+    }),
+    delete: params => ({
+      endpoint: `/_synapse/admin/v2/users/${params.user_id}/devices/${params.id}`,
+    }),
+  },
   connections: {
     path: "/_synapse/admin/v1/whois",
     map: c => ({
@@ -166,30 +179,18 @@ const dataProvider = {
   },
 
   getManyReference: (resource, params) => {
-    // FIXME
     console.log("getManyReference " + resource);
-    const { page, perPage } = params.pagination;
-    const { field, order } = params.sort;
-    const query = {
-      sort: JSON.stringify([field, order]),
-      range: JSON.stringify([(page - 1) * perPage, page * perPage - 1]),
-      filter: JSON.stringify({
-        ...params.filter,
-        [params.target]: params.id,
-      }),
-    };
 
     const homeserver = localStorage.getItem("base_url");
     if (!homeserver || !(resource in resourceMap)) return Promise.reject();
 
     const res = resourceMap[resource];
 
-    const endpoint_url = homeserver + res.path;
-    const url = `${endpoint_url}?${stringify(query)}`;
+    const ref = res["reference"](params.id);
+    const endpoint_url = homeserver + ref.endpoint;
 
-    return jsonClient(url).then(({ headers, json }) => ({
-      data: json,
-      total: parseInt(headers.get("content-range").split("/").pop(), 10),
+    return jsonClient(endpoint_url).then(({ headers, json }) => ({
+      data: json[res.data].map(res.map),
     }));
   },
 
@@ -276,11 +277,11 @@ const dataProvider = {
     const res = resourceMap[resource];
 
     if ("delete" in res) {
-      const del = res["delete"](params.id);
+      const del = res["delete"](params);
       const endpoint_url = homeserver + del.endpoint;
       return jsonClient(endpoint_url, {
-        method: del.method,
-        body: JSON.stringify(del.body),
+        method: "method" in del ? del.method : "DELETE",
+        body: "body" in del ? JSON.stringify(del.body) : null,
       }).then(({ json }) => ({
         data: json,
       }));
@@ -305,11 +306,11 @@ const dataProvider = {
     if ("delete" in res) {
       return Promise.all(
         params.ids.map(id => {
-          const del = res["delete"](id);
+          const del = res["delete"]({ ...params, id: id });
           const endpoint_url = homeserver + del.endpoint;
           return jsonClient(endpoint_url, {
-            method: del.method,
-            body: JSON.stringify(del.body),
+            method: "method" in del ? del.method : "DELETE",
+            body: "body" in del ? JSON.stringify(del.body) : null,
           });
         })
       ).then(responses => ({
diff --git a/src/synapse/dataProvider.test.js b/src/synapse/dataProvider.test.js
new file mode 100644
index 0000000..a6563b7
--- /dev/null
+++ b/src/synapse/dataProvider.test.js
@@ -0,0 +1,78 @@
+import dataProvider from "./dataProvider";
+
+beforeEach(() => {
+  fetch.resetMocks();
+});
+
+describe("dataProvider", () => {
+  localStorage.setItem("base_url", "http://localhost");
+  localStorage.setItem("access_token", "access_token");
+
+  it("fetches all users", async () => {
+    fetch.mockResponseOnce(
+      JSON.stringify({
+        users: [
+          {
+            name: "user_id1",
+            password_hash: "password_hash1",
+            is_guest: 0,
+            admin: 0,
+            user_type: null,
+            deactivated: 0,
+            displayname: "User One",
+          },
+          {
+            name: "user_id2",
+            password_hash: "password_hash2",
+            is_guest: 0,
+            admin: 1,
+            user_type: null,
+            deactivated: 0,
+            displayname: "User Two",
+          },
+        ],
+        next_token: "100",
+        total: 200,
+      })
+    );
+
+    const users = await dataProvider.getList("users", {
+      pagination: { page: 1, perPage: 5 },
+      sort: { field: "title", order: "ASC" },
+      filter: { author_id: 12 },
+    });
+
+    expect(users["data"][0]["id"]).toEqual("user_id1");
+    expect(users["total"]).toEqual(200);
+    expect(fetch).toHaveBeenCalledTimes(1);
+  });
+
+  it("fetches one user", async () => {
+    fetch.mockResponseOnce(
+      JSON.stringify({
+        name: "user_id1",
+        password: "user_password",
+        displayname: "User",
+        threepids: [
+          {
+            medium: "email",
+            address: "user@mail_1.com",
+          },
+          {
+            medium: "email",
+            address: "user@mail_2.com",
+          },
+        ],
+        avatar_url: "mxc://localhost/user1",
+        admin: false,
+        deactivated: false,
+      })
+    );
+
+    const user = await dataProvider.getOne("users", { id: "user_id1" });
+
+    expect(user["data"]["id"]).toEqual("user_id1");
+    expect(user["data"]["displayname"]).toEqual("User");
+    expect(fetch).toHaveBeenCalledTimes(1);
+  });
+});
diff --git a/yarn.lock b/yarn.lock
index 7607589..b20f394 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -3502,6 +3502,13 @@ create-hmac@^1.1.0, create-hmac@^1.1.4, create-hmac@^1.1.7:
     safe-buffer "^5.0.1"
     sha.js "^2.4.8"
 
+cross-fetch@^3.0.4:
+  version "3.0.5"
+  resolved "https://registry.yarnpkg.com/cross-fetch/-/cross-fetch-3.0.5.tgz#2739d2981892e7ab488a7ad03b92df2816e03f4c"
+  integrity sha512-FFLcLtraisj5eteosnX1gf01qYDCOc4fDy0+euOt8Kn9YBY2NtXL/pCoYPavw24NIQkQqm5ZOLsGD5Zzj0gyew==
+  dependencies:
+    node-fetch "2.6.0"
+
 cross-spawn@7.0.1:
   version "7.0.1"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.1.tgz#0ab56286e0f7c24e153d04cc2aa027e43a9a5d14"
@@ -6447,6 +6454,14 @@ jest-environment-node@^24.9.0:
     jest-mock "^24.9.0"
     jest-util "^24.9.0"
 
+jest-fetch-mock@^3.0.3:
+  version "3.0.3"
+  resolved "https://registry.yarnpkg.com/jest-fetch-mock/-/jest-fetch-mock-3.0.3.tgz#31749c456ae27b8919d69824f1c2bd85fe0a1f3b"
+  integrity sha512-Ux1nWprtLrdrH4XwE7O7InRY6psIi3GOsqNESJgMJ+M5cv4A8Lh7SN9d2V2kKRZ8ebAfcd1LNyZguAOb6JiDqw==
+  dependencies:
+    cross-fetch "^3.0.4"
+    promise-polyfill "^8.1.3"
+
 jest-get-type@^24.9.0:
   version "24.9.0"
   resolved "https://registry.yarnpkg.com/jest-get-type/-/jest-get-type-24.9.0.tgz#1684a0c8a50f2e4901b6644ae861f579eed2ef0e"
@@ -7650,6 +7665,11 @@ no-case@^3.0.3:
     lower-case "^2.0.1"
     tslib "^1.10.0"
 
+node-fetch@2.6.0:
+  version "2.6.0"
+  resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-2.6.0.tgz#e633456386d4aa55863f676a7ab0daa8fdecb0fd"
+  integrity sha512-8dG4H5ujfvFiqDmVu9fQ5bOHUC15JMjMY/Zumv26oOvvVJjM67KF8koCWIabKQ1GJIa9r2mMZscBq/TbdOcmNA==
+
 node-fetch@^1.0.1:
   version "1.7.3"
   resolved "https://registry.yarnpkg.com/node-fetch/-/node-fetch-1.7.3.tgz#980f6f72d85211a5347c6b2bc18c5b84c3eb47ef"
@@ -9131,6 +9151,11 @@ promise-inflight@^1.0.1:
   resolved "https://registry.yarnpkg.com/promise-inflight/-/promise-inflight-1.0.1.tgz#98472870bf228132fcbdd868129bad12c3c029e3"
   integrity sha1-mEcocL8igTL8vdhoEputEsPAKeM=
 
+promise-polyfill@^8.1.3:
+  version "8.1.3"
+  resolved "https://registry.yarnpkg.com/promise-polyfill/-/promise-polyfill-8.1.3.tgz#8c99b3cf53f3a91c68226ffde7bde81d7f904116"
+  integrity sha512-MG5r82wBzh7pSKDRa9y+vllNHz3e3d4CNj1PQE4BQYxLme0gKYYBm9YENq+UkEikyZ0XbiGWxYlVw3Rl9O/U8g==
+
 promise@^7.1.1:
   version "7.3.1"
   resolved "https://registry.yarnpkg.com/promise/-/promise-7.3.1.tgz#064b72602b18f90f29192b8b1bc418ffd1ebd3bf"