diff --git a/build.gradle.kts b/build.gradle.kts
index ba4aeb28..581b817d 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -71,6 +71,7 @@ subprojects {
  * The set of names of modules that required for building the `desktop` standalone project.
  */
 val modulesRequiredForDesktop = setOf(
+    "clock",
     "github",
     "sessions",
     "mentions",
diff --git a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
index 6b174333..1801c345 100644
--- a/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
+++ b/buildSrc/src/main/kotlin/io/spine/internal/dependency/Spine.kt
@@ -33,16 +33,15 @@ public object Spine {
      * in `build.gradle.kts` in each module.
      */
     private const val version = "1.9.0"
+    private const val group = "io.spine"
 
-    // https://github.com/SpineEventEngine/core-java
-    public object Server {
-        private const val group = "io.spine"
-        public const val lib: String = "$group:spine-server:$version"
-    }
+    public const val base: String = "$group:spine-base:$version"
+    public const val time: String = "$group:spine-time:$version"
+    public const val server: String = "$group:spine-server:$version"
 
     // https://github.com/SpineEventEngine/gcloud-java
     public object GCloud {
-        private const val group = "io.spine.gcloud"
+        private const val group = "${Spine.group}.gcloud"
         public const val datastore: String = "$group:spine-datastore:$version"
         public const val testutil: String = "$group:spine-testutil-gcloud:$version"
     }
diff --git a/client/build.gradle.kts b/client/build.gradle.kts
index 8fc72dba..09f6d644 100644
--- a/client/build.gradle.kts
+++ b/client/build.gradle.kts
@@ -56,7 +56,7 @@ dependencies {
     testImplementation(project(":testutil-mentions"))
     testImplementation(project(":testutil-sessions"))
     testImplementation(project(":clock"))
-    testImplementation(Spine.Server.lib)
+    testImplementation(Spine.server)
     testImplementation(Spine.GCloud.datastore)
     testImplementation(Spine.GCloud.testutil)
 }
diff --git a/client/src/main/kotlin/io/spine/examples/pingh/client/TimestampExts.kt b/client/src/main/kotlin/io/spine/examples/pingh/client/TimestampExts.kt
index 2d0ef25e..5bcee338 100644
--- a/client/src/main/kotlin/io/spine/examples/pingh/client/TimestampExts.kt
+++ b/client/src/main/kotlin/io/spine/examples/pingh/client/TimestampExts.kt
@@ -28,9 +28,10 @@ package io.spine.examples.pingh.client
 
 import com.google.protobuf.Timestamp
 import com.google.protobuf.util.Timestamps
+import io.spine.time.InstantConverter
 import java.time.Duration
 import java.time.LocalDateTime
-import java.time.ZoneOffset
+import java.time.ZoneId
 import java.time.format.DateTimeFormatter
 
 /**
@@ -64,15 +65,17 @@ internal fun Timestamp.add(duration: com.google.protobuf.Duration): Timestamp =
  * - If the difference is exactly one day, returns the string `"yesterday"`;
  * - In all other cases, returns the day and month.
  *
+ * @receiver The timestamp represents a time in the past.
  * @throws IllegalArgumentException if the `Timestamp` is not from the past.
  */
 public fun Timestamp.howMuchTimeHasPassed(): String {
-    val thisDatetime = LocalDateTime.ofEpochSecond(this.seconds, this.nanos, ZoneOffset.UTC)
-    val difference = Duration.between(
-        thisDatetime,
-        LocalDateTime.now(ZoneOffset.UTC)
-    )
-    require(difference > Duration.ZERO) { "" }
+    val thisDatetime = this.asLocalDateTime()
+    val now = LocalDateTime.now()
+    val difference = Duration.between(thisDatetime, now)
+    require(difference > Duration.ZERO) {
+        "The provided `Timestamp`, $thisDatetime, must represent a time in the past, " +
+                "but it does not. The current time is $now."
+    }
     return when {
         difference.toMinutes() < 1L -> "just now"
         difference.toMinutes() == 1L -> "a minute ago"
@@ -83,3 +86,15 @@ public fun Timestamp.howMuchTimeHasPassed(): String {
         else -> dateFormat.format(thisDatetime)
     }
 }
+
+/**
+ * Converts the current UTC time in this `Timestamp` to local time,
+ * based on the system's time zone.
+ *
+ * The default time zone is set to the [ZoneId.systemDefault()][ZoneId.systemDefault] zone.
+ */
+public fun Timestamp.asLocalDateTime(timeZone: ZoneId = ZoneId.systemDefault()): LocalDateTime {
+    val instant = InstantConverter.reversed()
+        .convert(this)
+    return LocalDateTime.ofInstant(instant, timeZone)
+}
diff --git a/desktop/build.gradle.kts b/desktop/build.gradle.kts
index c5e4ef97..3a78d120 100644
--- a/desktop/build.gradle.kts
+++ b/desktop/build.gradle.kts
@@ -45,6 +45,9 @@ plugins {
 
     // Adds and configures the Detekt for analysis code.
     id("detekt-code-analysis")
+
+    // Adds dependencies for testing and configure test-running tasks.
+    id("tests-configuration")
 }
 
 /**
diff --git a/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/JUnit.kt b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/JUnit.kt
new file mode 100644
index 00000000..918f8604
--- /dev/null
+++ b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/JUnit.kt
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2024, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.internal.dependency
+
+// https://github.com/junit-team/junit5/
+public object JUnit {
+    private const val version = "5.11.2"
+    private const val group = "org.junit.jupiter"
+
+    public const val engine: String = "$group:junit-jupiter-engine:${version}"
+}
diff --git a/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Kotest.kt b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Kotest.kt
new file mode 100644
index 00000000..1188fa8e
--- /dev/null
+++ b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Kotest.kt
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2024, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.internal.dependency
+
+// https://github.com/kotest/kotest
+public object Kotest {
+    private const val version = "5.9.1"
+    private const val group = "io.kotest"
+
+    public const val assertions: String = "$group:kotest-assertions-core:$version"
+}
diff --git a/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Pingh.kt b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Pingh.kt
index 5c3a6843..24fa5465 100644
--- a/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Pingh.kt
+++ b/desktop/buildSrc/src/main/kotlin/io/spine/internal/dependency/Pingh.kt
@@ -28,6 +28,6 @@ package io.spine.internal.dependency
 
 // https://github.com/spine-examples/Pingh
 public object Pingh {
-    private const val version = "1.0.0-SNAPSHOT.5"
+    private const val version = "1.0.0-SNAPSHOT.6"
     public const val client: String = "io.spine.examples.pingh:client:$version"
 }
diff --git a/desktop/buildSrc/src/main/kotlin/tests-configuration.gradle.kts b/desktop/buildSrc/src/main/kotlin/tests-configuration.gradle.kts
new file mode 100644
index 00000000..1c285cb6
--- /dev/null
+++ b/desktop/buildSrc/src/main/kotlin/tests-configuration.gradle.kts
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2024, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+import io.spine.internal.dependency.JUnit
+import io.spine.internal.dependency.Kotest
+
+plugins {
+    java
+}
+
+/**
+ * Add dependencies for testing.
+ */
+dependencies {
+    testImplementation(JUnit.engine)
+    testImplementation(Kotest.assertions)
+}
+
+/**
+ * Explicitly instructs to discover and execute JUnit tests.
+ */
+tasks.withType<Test> {
+    useJUnitPlatform {
+        includeEngines("junit-jupiter")
+    }
+}
diff --git a/desktop/src/main/kotlin/io/spine/examples/pingh/desktop/TimestampExts.kt b/desktop/src/main/kotlin/io/spine/examples/pingh/desktop/TimestampExts.kt
index aa467a9d..953f3d52 100644
--- a/desktop/src/main/kotlin/io/spine/examples/pingh/desktop/TimestampExts.kt
+++ b/desktop/src/main/kotlin/io/spine/examples/pingh/desktop/TimestampExts.kt
@@ -27,8 +27,8 @@
 package io.spine.examples.pingh.desktop
 
 import com.google.protobuf.Timestamp
-import java.time.LocalDateTime
-import java.time.ZoneOffset
+import io.spine.examples.pingh.client.asLocalDateTime
+import java.time.ZoneId
 import java.time.format.DateTimeFormatter
 
 /**
@@ -44,11 +44,5 @@ private val datetimeFormat = DateTimeFormatter.ofPattern("dd MMM HH:mm")
  * - `10 May 14:37`
  * - `05 Sep 04:00`
  */
-internal fun Timestamp.toDatetime(): String =
-    datetimeFormat.format(toLocalDateTime())
-
-/**
- * Converts this `Timestamp` to `LocalDateTime`.
- */
-private fun Timestamp.toLocalDateTime(): LocalDateTime =
-    LocalDateTime.ofEpochSecond(this.seconds, this.nanos, ZoneOffset.UTC)
+internal fun Timestamp.toDatetime(timeZone: ZoneId = ZoneId.systemDefault()): String =
+    datetimeFormat.format(this.asLocalDateTime(timeZone))
diff --git a/desktop/src/test/kotlin/io/spine/examples/pingh/desktop/TimestampExtsSpec.kt b/desktop/src/test/kotlin/io/spine/examples/pingh/desktop/TimestampExtsSpec.kt
new file mode 100644
index 00000000..a9bb0809
--- /dev/null
+++ b/desktop/src/test/kotlin/io/spine/examples/pingh/desktop/TimestampExtsSpec.kt
@@ -0,0 +1,35 @@
+package io.spine.examples.pingh.desktop
+
+import com.google.protobuf.util.Timestamps
+import io.kotest.matchers.shouldBe
+import java.time.ZoneId
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+
+@DisplayName("`Timestamp` extensions should")
+internal class TimestampExtsSpec {
+
+    @Test
+    internal fun `consider the time difference when converting UTC time to local time`() {
+        val time = Timestamps.parse("2024-10-09T10:00:00Z")
+        val expected = "09 Oct 13:00"
+        val timeZone = ZoneId.of("+03:00")
+        time.toDatetime(timeZone) shouldBe expected
+    }
+
+    @Test
+    internal fun `consider the date difference when converting UTC time to local time`() {
+        val time = Timestamps.parse("2024-10-09T03:12:43Z")
+        val expected = "08 Oct 23:12"
+        val timeZone = ZoneId.of("America/New_York")
+        time.toDatetime(timeZone) shouldBe expected
+    }
+
+    @Test
+    internal fun `consider the daylight saving time when converting UTC time to local time`() {
+        val time = Timestamps.parse("2024-06-09T15:00:00Z")
+        val expected = "09 Jun 16:00"
+        val timeZone = ZoneId.of("Europe/London")
+        time.toDatetime(timeZone) shouldBe expected
+    }
+}
diff --git a/github/build.gradle.kts b/github/build.gradle.kts
index 439c2ac7..e0aabf9e 100644
--- a/github/build.gradle.kts
+++ b/github/build.gradle.kts
@@ -24,6 +24,8 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+import io.spine.internal.dependency.Spine
+
 plugins {
     // Add the Gradle plugin for bootstrapping projects built with Spine.
     // See: https://github.com/SpineEventEngine/bootstrap
@@ -36,3 +38,7 @@ spine {
     assembleModel()
     enableJava()
 }
+
+dependencies {
+    implementation(Spine.time)
+}
diff --git a/github/src/main/kotlin/io/spine/examples/pingh/github/TimestampExts.kt b/github/src/main/kotlin/io/spine/examples/pingh/github/TimestampExts.kt
new file mode 100644
index 00000000..c3bb9ba3
--- /dev/null
+++ b/github/src/main/kotlin/io/spine/examples/pingh/github/TimestampExts.kt
@@ -0,0 +1,52 @@
+/*
+ * Copyright 2024, TeamDev. All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Redistribution and use in source and/or binary forms, with or without
+ * modification, must retain the above copyright notice and the following
+ * disclaimer.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package io.spine.examples.pingh.github
+
+import com.google.protobuf.Timestamp
+import com.google.protobuf.util.Timestamps
+import io.spine.time.InstantConverter
+import java.time.Instant
+import java.time.format.DateTimeParseException
+import kotlin.reflect.KClass
+
+/**
+ * Parses the time from a string in [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) format.
+ *
+ * Implementation details: The GitHub API provides time data in `ISO 8601` format,
+ * while [Timestamps.parse()][Timestamps.parse] expects time data in
+ * [RFC 3339](https://www.ietf.org/rfc/rfc3339.txt) format. To resolve this mismatch,
+ * the input string is first parsed into an [Instant], since it matches the `ISO 8601` format.
+ * The resulting `Instant` is then converted into a `Timestamp`.
+ *
+ * @throws DateTimeParseException if the provided string is not in `ISO 8601` format.
+ */
+@Suppress("UnusedReceiverParameter" /* Class extensions don't use class as a parameter. */)
+internal fun KClass<Timestamp>.parse(value: String): Timestamp {
+    val instant = Instant.parse(value)
+    return InstantConverter.instance()
+        .convert(instant)!!
+}
diff --git a/github/src/main/kotlin/io/spine/examples/pingh/github/ValuesExts.kt b/github/src/main/kotlin/io/spine/examples/pingh/github/ValuesExts.kt
index 2b2d35d4..ae12c511 100644
--- a/github/src/main/kotlin/io/spine/examples/pingh/github/ValuesExts.kt
+++ b/github/src/main/kotlin/io/spine/examples/pingh/github/ValuesExts.kt
@@ -28,6 +28,7 @@
 
 package io.spine.examples.pingh.github
 
+import com.google.protobuf.Timestamp
 import com.google.protobuf.util.Timestamps
 import io.spine.base.Time.currentTime
 import io.spine.examples.pingh.github.rest.AccessTokenFragment
@@ -114,7 +115,7 @@ public fun KClass<Mention>.from(fragment: IssueOrPullRequestFragment): Mention =
             fragment.whoCreated.avatarUrl
         )
         title = fragment.title
-        whenMentioned = Timestamps.parse(fragment.whenCreated)
+        whenMentioned = Timestamp::class.parse(fragment.whenCreated)
         url = Url::class.of(fragment.htmlUrl)
         vBuild()
     }
@@ -136,7 +137,7 @@ public fun KClass<Mention>.from(fragment: CommentFragment, itemTitle: String): M
             fragment.whoCreated.avatarUrl
         )
         title = "Comment on $itemTitle"
-        whenMentioned = Timestamps.parse(fragment.whenCreated)
+        whenMentioned = Timestamp::class.parse(fragment.whenCreated)
         url = Url::class.of(fragment.htmlUrl)
         vBuild()
     }
@@ -158,7 +159,7 @@ public fun KClass<Mention>.from(fragment: ReviewFragment, prTitle: String): Ment
             fragment.whoCreated.avatarUrl
         )
         title = "Review of $prTitle"
-        whenMentioned = Timestamps.parse(fragment.whenSubmitted)
+        whenMentioned = Timestamp::class.parse(fragment.whenSubmitted)
         url = Url::class.of(fragment.htmlUrl)
         vBuild()
     }
diff --git a/version.gradle.kts b/version.gradle.kts
index 8aa48c38..f12636e8 100644
--- a/version.gradle.kts
+++ b/version.gradle.kts
@@ -27,4 +27,4 @@
 /**
  * The version of the `Pingh` to publish.
  */
-val pinghVersion: String by extra("1.0.0-SNAPSHOT.5")
+val pinghVersion: String by extra("1.0.0-SNAPSHOT.6")