diff --git a/backend/src/plugins/Tags/TagsPlugin.ts b/backend/src/plugins/Tags/TagsPlugin.ts
index f3a488e2..18d65540 100644
--- a/backend/src/plugins/Tags/TagsPlugin.ts
+++ b/backend/src/plugins/Tags/TagsPlugin.ts
@@ -12,6 +12,9 @@ import { TagDeleteCmd } from "./commands/TagDeleteCmd";
 import { TagEvalCmd } from "./commands/TagEvalCmd";
 import { TagListCmd } from "./commands/TagListCmd";
 import { TagSourceCmd } from "./commands/TagSourceCmd";
+import moment from "moment-timezone";
+import humanizeDuration from "humanize-duration";
+import { convertDelayStringToMS } from "../../utils";
 
 const defaultOptions: PluginOptions<TagsPluginType> = {
   config: {
@@ -67,6 +70,114 @@ export const TagsPlugin = zeppelinPlugin<TagsPluginType>()("tags", {
 
     state.onMessageDeleteFn = msg => onMessageDelete(pluginData, msg);
     state.savedMessages.events.on("delete", state.onMessageDeleteFn);
+
+    state.tagFunctions = {
+      parseDateTime(str) {
+        if (typeof str === "number") {
+          return str; // Unix timestamp
+        }
+
+        if (typeof str !== "string") {
+          return Date.now();
+        }
+
+        return moment(str, "YYYY-MM-DD HH:mm:ss").valueOf();
+      },
+
+      countdown(toDate) {
+        const target = moment(this.parseDateTime(toDate));
+
+        const now = moment();
+        if (!target.isValid()) return "";
+
+        const diff = target.diff(now);
+        const result = humanizeDuration(diff, { largest: 2, round: true });
+        return diff >= 0 ? result : `${result} ago`;
+      },
+
+      now() {
+        return Date.now();
+      },
+
+      timeAdd(...args) {
+        let reference;
+        let delay;
+
+        if (args.length >= 2) {
+          // (time, delay)
+          reference = this.parseDateTime(args[0]);
+          delay = args[1];
+        } else {
+          // (delay), implicit "now" as time
+          reference = Date.now();
+          delay = args[0];
+        }
+
+        const delayMS = convertDelayStringToMS(delay);
+        return moment(reference)
+          .add(delayMS)
+          .valueOf();
+      },
+
+      timeSub(...args) {
+        let reference;
+        let delay;
+
+        if (args.length >= 2) {
+          // (time, delay)
+          reference = this.parseDateTime(args[0]);
+          delay = args[1];
+        } else {
+          // (delay), implicit "now" as time
+          reference = Date.now();
+          delay = args[0];
+        }
+
+        const delayMS = convertDelayStringToMS(delay);
+        return moment(reference)
+          .subtract(delayMS)
+          .valueOf();
+      },
+
+      timeAgo(delay) {
+        return this.timeSub(delay);
+      },
+
+      formatTime(time, format) {
+        const parsed = this.parseDateTime(time);
+        return moment(parsed).format(format);
+      },
+
+      discordDateFormat(time) {
+        const parsed = time ? this.parseDateTime(time) : Date.now();
+
+        return moment(parsed).format("YYYY-MM-DD");
+      },
+
+      mention: input => {
+        if (typeof input !== "string") {
+          return "";
+        }
+
+        if (input.match(/^<(@#)(!&)\d+>$/)) {
+          return input;
+        }
+
+        if (pluginData.guild.members.has(input) || pluginData.client.users.has(input)) {
+          return `<@!${input}>`;
+        }
+
+        if (pluginData.guild.channels.has(input) || pluginData.client.channelGuildMap[input]) {
+          return `<#${input}>`;
+        }
+
+        return "";
+      },
+    };
+
+    for (const [name, fn] of Object.entries(state.tagFunctions)) {
+      state.tagFunctions[name] = (fn as any).bind(state.tagFunctions);
+    }
   },
 
   onUnload(pluginData) {