diff --git a/src/contentScripts/communityConsole/extraInfo/injections/base.js b/src/contentScripts/communityConsole/extraInfo/injections/base.js
new file mode 100644
index 0000000..1498efd
--- /dev/null
+++ b/src/contentScripts/communityConsole/extraInfo/injections/base.js
@@ -0,0 +1,97 @@
+import {MDCTooltip} from '@material/tooltip';
+
+import {shouldImplement} from '../../../../common/commonUtils.js';
+import {createExtBadge} from '../../utils/common.js';
+
+export default class BaseExtraInfoInjection {
+  constructor(infoHandler, optionsWatcher) {
+    if (this.constructor == BaseExtraInfoInjection) {
+      throw new Error('The base class cannot be instantiated.');
+    }
+
+    this.infoHandler = infoHandler;
+    this.optionsWatcher = optionsWatcher;
+  }
+
+  /**
+   * Method which actually injects the extra information. It should be
+   * implemented by the extending class.
+   */
+  inject() {
+    shouldImplement('inject');
+  }
+
+  async isEnabled() {
+    return await this.optionsWatcher.isEnabled('extrainfo');
+  }
+
+  /**
+   * This is the method which should be called when injecting extra information.
+   */
+  async injectIfEnabled(injectionDetails) {
+    const isEnabled = await this.isEnabled();
+    if (!isEnabled) return;
+
+    return this.infoHandler.getCurrentInfo(injectionDetails)
+        .then(info => this.inject(info, injectionDetails))
+        .catch(err => {
+          console.error(
+              `${this.constructor.name}: error while injecting extra info: `,
+              err);
+        });
+  }
+
+  /**
+   * Add chips which contain |chipContentList| to |node|. If |withContainer| is
+   * set to true, a container will contain all the chips.
+   */
+  addExtraInfoChips(chipContentList, node, withContainer = false) {
+    if (chipContentList.length == 0) return;
+
+    let container;
+    if (withContainer) {
+      container = document.createElement('div');
+      container.classList.add('TWPT-extrainfo-container');
+    } else {
+      container = node;
+    }
+
+    let tooltips = [];
+
+    for (const content of chipContentList) {
+      const tooltip = this.addChipToContainer(content, container);
+      tooltips.push(tooltip);
+    }
+
+    if (withContainer) node.append(container);
+
+    for (const tooltip of tooltips) new MDCTooltip(tooltip);
+  }
+
+  /**
+   * Adds a chip to the container and returns a tooltip element to be
+   * instantiated.
+   */
+  addChipToContainer(chipContent, container) {
+    let chip = document.createElement('material-chip');
+    chip.classList.add('TWPT-extrainfo-chip');
+
+    let chipContentContainer = document.createElement('div');
+    chipContentContainer.classList.add('TWPT-chip-content-container');
+
+    let content = document.createElement('div');
+    content.classList.add('TWPT-content');
+
+    const [badge, badgeTooltip] = createExtBadge();
+
+    let span = document.createElement('span');
+    span.append(chipContent);
+
+    content.append(badge, span);
+    chipContentContainer.append(content);
+    chip.append(chipContentContainer);
+    container.append(chip);
+
+    return badgeTooltip;
+  }
+}