diff --git a/modules/effectie-time/shared/src/main/scala/effectie/time/TimeSource.scala b/modules/effectie-time/shared/src/main/scala/effectie/time/TimeSource.scala
new file mode 100644
index 00000000..aae4f522
--- /dev/null
+++ b/modules/effectie-time/shared/src/main/scala/effectie/time/TimeSource.scala
@@ -0,0 +1,94 @@
+package effectie.time
+
+import cats._
+import cats.syntax.all._
+import effectie.core._
+import effectie.syntax.all._
+import effectie.time.TimeSource.TimeSpent
+
+import java.time.Instant
+import scala.concurrent.duration.{FiniteDuration, MILLISECONDS, NANOSECONDS, SECONDS, TimeUnit}
+
+/** @author Kevin Lee
+  */
+trait TimeSource[F[*]] {
+
+  implicit protected def M: Monad[F]
+
+  def name: String
+
+  def currentTime(): F[Instant]
+
+  def realTimeTo(unit: TimeUnit): F[FiniteDuration]
+
+  def monotonicTo(unit: TimeUnit): F[FiniteDuration]
+
+  def realTime: F[FiniteDuration]
+
+  def monotonic: F[FiniteDuration]
+
+  def timeSpent[A](fa: => F[A]): F[(A, TimeSpent)] =
+    for {
+      start <- monotonic
+      a     <- fa
+      end   <- monotonic
+    } yield (a, TimeSpent(end - start))
+
+  override def toString: String = s"TimeSource(name=$name)"
+}
+
+object TimeSource {
+
+  def apply[F[*]: TimeSource]: TimeSource[F] = implicitly[TimeSource[F]]
+
+  implicit def showTimeSource[F[*]]: Show[TimeSource[F]] = Show.fromToString
+
+  def withSources[F[*]: Fx: Monad](
+    timeSourceName: String,
+    realTimeSource: F[Instant],
+    monotonicSource: F[Long],
+  ): TimeSource[F] =
+    new DefaultTimeSource[F](timeSourceName, realTimeSource, monotonicSource)
+
+  private class DefaultTimeSource[F[_]: Fx](
+    timeSourceName: String,
+    realTimeSource: F[Instant],
+    monotonicSource: F[Long],
+  )(implicit protected val M: Monad[F])
+      extends TimeSource[F] {
+
+    override val name: String = timeSourceName
+
+    override val toString: String = s"DefaultTimeSource(name=$name)"
+
+    override def currentTime(): F[Instant] = realTimeSource
+
+    override def realTimeTo(unit: TimeUnit): F[FiniteDuration] =
+      for {
+        now  <- currentTime()
+        real <- effectOf(unit.convert(now.getEpochSecond, SECONDS) + unit.convert(now.getNano.toLong, NANOSECONDS))
+      } yield FiniteDuration(real, unit)
+
+    override def monotonicTo(unit: TimeUnit): F[FiniteDuration] =
+      monotonicSource.map(nano => FiniteDuration(unit.convert(nano, NANOSECONDS), unit))
+
+    override def realTime: F[FiniteDuration] = realTimeTo(MILLISECONDS)
+
+    override def monotonic: F[FiniteDuration] = monotonicTo(NANOSECONDS)
+  }
+
+  /** The default behaviours of TimeSource depend on Instant and System.
+    * For realTime, it uses Instant.now() to get the epoch seconds and nano seconds.
+    * For monotonic, it uses System.nanoTime() to get the nano seconds.
+    *
+    * NOTE: To get the current time (Instant.now()), you should use realTime not monotonic.
+    */
+  def default[F[*]: Fx: Monad](timeSourceName: String): TimeSource[F] =
+    withSources(
+      timeSourceName,
+      effectOf(Instant.now()),
+      effectOf(System.nanoTime()),
+    )
+
+  final case class TimeSpent(timeSpent: FiniteDuration) extends AnyVal
+}
diff --git a/modules/effectie-time/shared/src/main/scala/effectie/time/syntax.scala b/modules/effectie-time/shared/src/main/scala/effectie/time/syntax.scala
index 80ddc018..3de3d01e 100644
--- a/modules/effectie-time/shared/src/main/scala/effectie/time/syntax.scala
+++ b/modules/effectie-time/shared/src/main/scala/effectie/time/syntax.scala
@@ -1,5 +1,7 @@
 package effectie.time
 
+import effectie.time.TimeSource.TimeSpent
+
 import scala.concurrent.duration.FiniteDuration
 
 /** @author Kevin Lee
@@ -8,6 +10,9 @@ import scala.concurrent.duration.FiniteDuration
 trait syntax {
   implicit def FiniteDurationExtraOps(finiteDuration: FiniteDuration): syntax.FiniteDurationExtraOps =
     new syntax.FiniteDurationExtraOps(finiteDuration)
+
+  implicit def fAWithTimeOps[F[*], A](fa: F[A]): syntax.FAWithTimeOps[F[*], A] = new syntax.FAWithTimeOps[F[*], A](fa)
+
 }
 object syntax extends syntax {
   final class FiniteDurationExtraOps(private val finiteDuration: FiniteDuration) extends AnyVal {
@@ -18,4 +23,8 @@ object syntax extends syntax {
       finiteDuration >= approxFiniteDuration.min && finiteDuration <= approxFiniteDuration.max
   }
 
+  final class FAWithTimeOps[F[*], A](private val fa: F[A]) extends AnyVal {
+    def withTimeSpent(implicit timeSource: TimeSource[F]): F[(A, TimeSpent)] = timeSource.timeSpent(fa)
+  }
+
 }
diff --git a/modules/effectie-time/shared/src/test/scala/effectie/time/TimeSourceSpec.scala b/modules/effectie-time/shared/src/test/scala/effectie/time/TimeSourceSpec.scala
new file mode 100644
index 00000000..7b29e7d5
--- /dev/null
+++ b/modules/effectie-time/shared/src/test/scala/effectie/time/TimeSourceSpec.scala
@@ -0,0 +1,241 @@
+package effectie.time
+
+import cats.effect._
+import cats.syntax.all._
+import effectie.syntax.all._
+import effectie.time.syntax._
+import hedgehog._
+import hedgehog.runner._
+
+import java.time.Instant
+import scala.concurrent.duration._
+
+object TimeSourceSpec extends Properties {
+  import effectie.instances.ce2.fx.ioFx
+
+  type F[A] = IO[A]
+  val F = IO
+
+  implicit val timer: Timer[F] = F.timer(scala.concurrent.ExecutionContext.global)
+
+  override def tests: List[Test] = List(
+    example("test Show[TimeSource]", testShowTimeSource),
+    example("example test realTime and monotonic", testRealTimeAndMonotonicExample),
+    property("property test realTime and monotonic", testRealTimeAndMonotonicProperty),
+    example("test default TimeSource - realTime", testDefaultTimeSourceRealTime),
+    example("test default TimeSource - monotonic", testDefaultTimeSourceMonotonic),
+    property("test default TimeSource - timeSpent", testDefaultTimeSourceTimeSpent).withTests(count = 5),
+  )
+
+  private def runIO(test: F[Result]): Result = test.unsafeRunSync()
+
+  def testShowTimeSource: Result = {
+    val name     = "test TimeSource"
+    val expected = s"DefaultTimeSource(name=$name)"
+    val actual   = TimeSource.default[F](name).show
+    actual ==== expected
+  }
+
+  def testRealTimeAndMonotonicExample: Result = runIO {
+    val epochSeconds = 123456789L
+    val nanoSeconds  = 123456789L
+    val fullNanos    = epochSeconds * 1000000000L + nanoSeconds
+
+    val expectedMillis = fullNanos / 1000000L
+    val expectedNanos  = fullNanos
+
+    implicit val sourcedTimeSource: TimeSource[F] = TimeSource.withSources[F](
+      "Test",
+      pureOf(Instant.ofEpochSecond(epochSeconds, nanoSeconds)),
+      pureOf(fullNanos),
+    )
+
+    val timeSource = TimeSource[F]
+
+    import scala.concurrent.duration._
+    List(
+      timeSource
+        .realTime
+        .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.realTime")),
+      timeSource
+        .realTimeTo(MILLISECONDS)
+        .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.realTimeTo(MILLISECONDS)")),
+      timeSource
+        .realTimeTo(NANOSECONDS)
+        .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.realTimeTo(NANOSECONDS)")),
+      timeSource
+        .monotonic
+        .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.monotonic")),
+      timeSource
+        .monotonicTo(MILLISECONDS)
+        .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.monotonicTo(MILLISECONDS)")),
+      timeSource
+        .monotonicTo(NANOSECONDS)
+        .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.monotonicTo(NANOSECONDS)")),
+    ).sequence
+      .map(Result.all)
+  }
+
+  def testRealTimeAndMonotonicProperty: Property = {
+    for {
+      epochSeconds <- Gen.long(Range.linear(1L, 999999999L)).log("epochSeconds")
+      nanoSeconds  <- Gen.long(Range.linear(1L, 999999999L)).log("nanoSeconds")
+      fullNanos    <- Gen.constant(epochSeconds * 1000000000L + nanoSeconds).log("fullNanos")
+
+    } yield runIO {
+      val expectedMillis = fullNanos / 1000000L
+      val expectedNanos  = fullNanos
+
+      val timeSource = TimeSource.withSources[F](
+        "Test",
+        pureOf(Instant.ofEpochSecond(epochSeconds, nanoSeconds)),
+        pureOf(fullNanos),
+      )
+
+      import scala.concurrent.duration._
+      List(
+        timeSource
+          .realTime
+          .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.realTime")),
+        timeSource
+          .realTimeTo(MILLISECONDS)
+          .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.realTimeTo(MILLISECONDS)")),
+        timeSource
+          .realTimeTo(NANOSECONDS)
+          .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.realTimeTo(NANOSECONDS)")),
+        timeSource
+          .monotonic
+          .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.monotonic")),
+        timeSource
+          .monotonicTo(MILLISECONDS)
+          .map(time => (time ==== expectedMillis.milliseconds).log("timeSource.monotonicTo(MILLISECONDS)")),
+        timeSource
+          .monotonicTo(NANOSECONDS)
+          .map(time => (time ==== expectedNanos.nanoseconds).log("timeSource.monotonicTo(NANOSECONDS)")),
+      ).sequence
+        .map(Result.all)
+    }
+  }
+
+  def testDefaultTimeSourceRealTime: Result = runIO {
+
+    val now            = Instant.now()
+    val expectedNanos  = now.getEpochSecond * 1000000000L + now.getNano
+    val expectedMillis = expectedNanos / 1000000L
+
+    val timeSource = TimeSource.default[F](
+      "Test"
+    )
+
+    List(
+      timeSource
+        .realTime
+        .map(time =>
+          Result
+            .diff(time, (expectedMillis.milliseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.realTime"),
+        ),
+      timeSource
+        .realTimeTo(MILLISECONDS)
+        .map(time =>
+          Result
+            .diff(time, (expectedMillis.milliseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.realTimeTo(MILLISECONDS)"),
+        ),
+      timeSource
+        .realTimeTo(NANOSECONDS)
+        .map(time =>
+          Result
+            .diff(time, (expectedNanos.nanoseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.realTimeTo(NANOSECONDS)"),
+        ),
+    ).sequence
+      .map(Result.all)
+  }
+
+  def testDefaultTimeSourceMonotonic: Result = runIO {
+
+    val expectedNanos  = System.nanoTime()
+    val expectedMillis = expectedNanos / 1000000L
+
+    val timeSource = TimeSource.default[F](
+      "Test"
+    )
+
+    List(
+      timeSource
+        .monotonic
+        .map(time =>
+          Result
+            .diff(time, (expectedNanos.nanoseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.monotonic"),
+        ),
+      timeSource
+        .monotonicTo(MILLISECONDS)
+        .map(time =>
+          Result
+            .diff(time, (expectedMillis.milliseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.monotonicTo(MILLISECONDS)"),
+        ),
+      timeSource
+        .monotonicTo(NANOSECONDS)
+        .map(time =>
+          Result
+            .diff(time, (expectedNanos.nanoseconds +- 1000.milliseconds))(_.isWithIn(_))
+            .log("timeSource.monotonicTo(NANOSECONDS)"),
+        ),
+    ).sequence
+      .map(Result.all)
+  }
+
+  def testDefaultTimeSourceTimeSpent: Property = {
+    for {
+      waitFor <- Gen.int(Range.linear(200, 700)).map(_.milliseconds).log("waitFor")
+      diff    <- Gen.constant(180.milliseconds).log("diff")
+    } yield runIO {
+      val timeSource = TimeSource.default[F](
+        "Test"
+      )
+
+      for {
+        _                  <- F.sleep(500.milliseconds) // warm up
+        resultAndTimeSpent <- timeSource.timeSpent {
+                                F.sleep(waitFor) *>
+                                  pureOf("Done")
+                              }
+        (result, timeSpent) = resultAndTimeSpent
+        _ <- effectOf(
+               println(
+                 s""">>>   waitFor: ${waitFor.show}
+                    |>>> timeSpent: ${timeSpent.timeSpent.toMillis.show} milliseconds
+                    |>>>      diff: ${(timeSpent.timeSpent - waitFor).toMillis.show} milliseconds
+                    |""".stripMargin
+               )
+             )
+      } yield {
+        Result.all(
+          List(
+            result ==== "Done",
+            Result
+              .diffNamed(
+                s"timeSpent (${timeSpent.timeSpent.toMillis.show} milliseconds) should be " +
+                  s"within ${(waitFor - diff).show} to ${(waitFor + diff).show}.",
+                timeSpent,
+                (waitFor +- diff),
+              )(_.timeSpent.isWithIn(_))
+              .log(
+                s"""--- diff test log ---
+                   |>         actual: ${timeSpent.timeSpent.toMillis.show} milliseconds
+                   |> expected range: ${(waitFor - diff).show} to ${(waitFor + diff).show}
+                   |>        waitFor: ${waitFor.show}
+                   |>  expected diff: +- ${diff.show})
+                   |>    actual diff: ${(timeSpent.timeSpent - waitFor).toMillis.show} milliseconds
+                   |""".stripMargin
+              ),
+          )
+        )
+      }
+    }
+  }
+
+}
diff --git a/modules/effectie-time/shared/src/test/scala/effectie/time/syntaxSpec.scala b/modules/effectie-time/shared/src/test/scala/effectie/time/syntaxSpec.scala
index b0c40035..4d308fd5 100644
--- a/modules/effectie-time/shared/src/test/scala/effectie/time/syntaxSpec.scala
+++ b/modules/effectie-time/shared/src/test/scala/effectie/time/syntaxSpec.scala
@@ -1,6 +1,8 @@
 package effectie.time
 
+import cats.effect.{IO, Timer}
 import cats.syntax.all._
+import effectie.syntax.all._
 import effectie.time.syntax._
 import hedgehog._
 import hedgehog.runner._
@@ -12,12 +14,22 @@ import scala.concurrent.duration._
   */
 object syntaxSpec extends Properties {
 
+  import effectie.instances.ce2.fx.ioFx
+
+  type F[A] = IO[A]
+  val F = IO
+
+  implicit val timer: Timer[F] = F.timer(scala.concurrent.ExecutionContext.global)
+
   override def tests: List[Test] = List(
     property("test FiniteDuration +- FiniteDuration to create ApproxFiniteDuration", testPlusMinus),
     property("test FiniteDuration.isWithIn(ApproxFiniteDuration) with valid FiniteDuration", testIsWithInValid),
     property("test FiniteDuration.isWithIn(ApproxFiniteDuration) with invalid FiniteDuration", testIsWithInInvalid),
+    property("test F[A].withTimeSpent", testWithTimeSpent).withTests(count = 5),
   )
 
+  private def runIO(test: F[Result]): Result = test.unsafeRunSync()
+
   def testPlusMinus: Property =
     for {
       tolerance <- Gen.int(Range.linear(0, Int.MaxValue >> 1)).log("tolerance")
@@ -96,4 +108,54 @@ object syntaxSpec extends Properties {
       )
     }
 
+  def testWithTimeSpent: Property = {
+    for {
+      waitFor <- Gen.int(Range.linear(200, 700)).map(_.milliseconds).log("waitFor")
+      diff    <- Gen.constant(180.milliseconds).log("diff")
+      approx  <- Gen.constant(waitFor +- diff).log("approx")
+    } yield runIO {
+      implicit val timeSource: TimeSource[F] = TimeSource.default[F]("Test")
+
+      for {
+        _                  <- F.sleep(500.milliseconds) // warm up
+        resultAndTimeSpent <- {
+                                F.sleep(waitFor) *>
+                                  pureOf("Done")
+                              }.withTimeSpent
+        (result, timeSpent) = resultAndTimeSpent
+        _ <- effectOf(
+               println(
+                 show""">>>        waitFor: $waitFor
+                       |>>>      timeSpent: ${timeSpent.timeSpent.toMillis} milliseconds
+                       |>>>           diff: ${(timeSpent.timeSpent - waitFor).toMillis} milliseconds
+                       |>>> expected range: $approx
+                       |""".stripMargin
+               )
+             )
+      } yield {
+        Result.all(
+          List(
+            result ==== "Done",
+            Result
+              .diffNamed(
+                s"timeSpent (${timeSpent.timeSpent.toMillis.show} milliseconds) should be " +
+                  show"within $approx.",
+                timeSpent,
+                approx,
+              )(_.timeSpent.isWithIn(_))
+              .log(
+                show"""--- diff test log ---
+                      |>         actual: ${timeSpent.timeSpent.toMillis.show} milliseconds
+                      |> expected range: $approx
+                      |>        waitFor: ${waitFor.show}
+                      |>  expected diff: +- ${diff.show})
+                      |>    actual diff: ${(timeSpent.timeSpent - waitFor).toMillis.show} milliseconds
+                      |""".stripMargin
+              ),
+          )
+        )
+      }
+    }
+  }
+
 }