diff --git a/index.js b/index.js
index 1cfa0e2..00a3123 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,7 @@
 const TemplatePath = require("./src/TemplatePath.js");
 const isPlainObject = require("./src/IsPlainObject.js");
 const Merge = require("./src/Merge.js");
+const DateCompare = require("./src/DateCompare.js");
 const { DeepCopy } = Merge;
 
 module.exports = {
@@ -8,4 +9,5 @@ module.exports = {
   isPlainObject,
   Merge,
   DeepCopy,
+  DateCompare,
 };
\ No newline at end of file
diff --git a/package.json b/package.json
index 8fe2594..5d9e5d4 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,8 @@
     "!test/**"
   ],
   "scripts": {
-    "test": "node --test"
+    "test": "node --test",
+    "watch": "node --test --watch"
   },
   "license": "MIT",
   "engines": {
diff --git a/src/DateCompare.js b/src/DateCompare.js
new file mode 100644
index 0000000..7850152
--- /dev/null
+++ b/src/DateCompare.js
@@ -0,0 +1,43 @@
+class DateCompare {
+	static isTimestampWithinDuration(timestamp, duration, compareDate = Date.now()) {
+		// in the cache and no duration
+		if (!duration || duration === "*" || duration === Infinity) {
+			// no duration specified (plugin default is 1d, but if this is falsy assume infinite)
+			// "*" is infinite duration
+			return true;
+		}
+
+		let expiration = timestamp + this.getDurationMs(duration);
+
+		// still valid
+		if (expiration > compareDate) {
+			return true;
+		}
+
+		// expired
+		return false;
+	}
+
+	static getDurationMs(duration = "0s") {
+		let durationUnits = duration.slice(-1);
+		let durationMultiplier;
+		if (durationUnits === "s") {
+			durationMultiplier = 1;
+		} else if (durationUnits === "m") {
+			durationMultiplier = 60;
+		} else if (durationUnits === "h") {
+			durationMultiplier = 60 * 60;
+		} else if (durationUnits === "d") {
+			durationMultiplier = 60 * 60 * 24;
+		} else if (durationUnits === "w") {
+			durationMultiplier = 60 * 60 * 24 * 7;
+		} else if (durationUnits === "y") {
+			durationMultiplier = 60 * 60 * 24 * 365;
+		}
+
+		let durationValue = parseInt(duration.slice(0, duration.length - 1), 10);
+		return durationValue * durationMultiplier * 1000;
+	}
+}
+
+module.exports = DateCompare;
\ No newline at end of file
diff --git a/test/DateCompareTest.js b/test/DateCompareTest.js
new file mode 100644
index 0000000..0442093
--- /dev/null
+++ b/test/DateCompareTest.js
@@ -0,0 +1,39 @@
+const assert = require("node:assert/strict")
+const test = require("node:test");
+
+const DateCompare = require("../src/DateCompare.js");
+
+test("Basic usage empty duration is the same as infinite duration", (t) => {
+	let jan1 = Date.UTC(2024,0,1);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1), true);
+	assert.equal(DateCompare.isTimestampWithinDuration(Date.now()), true);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1, Infinity), true);
+	assert.equal(DateCompare.isTimestampWithinDuration(Date.now(), Infinity), true);
+});
+
+test("Basic usage false, now", (t) => {
+	assert.equal(DateCompare.isTimestampWithinDuration(Date.now(), "0s"), false);
+	assert.equal(DateCompare.isTimestampWithinDuration(Date.now(), "0s", Date.now()), false);
+});
+
+test("Basic usage false, old date", (t) => {
+	let jan1 = Date.UTC(2024,0,1);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1, "24h"), false);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1, "24h", Date.now()), false);
+});
+
+test("Basic usage true, now", (t) => {
+	assert.equal(DateCompare.isTimestampWithinDuration(Date.now(), "1s"), true);
+});
+
+test("Basic usage true, old date", (t) => {
+	let jan1 = Date.UTC(2024,0,1);
+	let jan2 = Date.UTC(2024,0,2);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1, "25h", jan2), true);
+});
+
+test("Basic usage equality is false, needs to be > not >=", (t) => {
+	let jan1 = Date.UTC(2024,0,1);
+	let jan2 = Date.UTC(2024,0,2);
+	assert.equal(DateCompare.isTimestampWithinDuration(jan1, "24h", jan2), false);
+});
\ No newline at end of file