diff --git a/core/model/build.gradle.kts b/core/model/build.gradle.kts
index fc770724a..5c609d405 100644
--- a/core/model/build.gradle.kts
+++ b/core/model/build.gradle.kts
@@ -10,6 +10,7 @@ android.namespace = "io.github.droidkaigi.confsched2023.core.model"
 
 @Suppress("UnusedPrivateProperty")
 kotlin {
+    explicitApi()
     sourceSets {
         commonMain {
             dependencies {
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/data/contributors/StampRepository.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/data/contributors/StampRepository.kt
index a5d2c3125..285afa200 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/data/contributors/StampRepository.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/data/contributors/StampRepository.kt
@@ -2,7 +2,7 @@ package io.github.droidkaigi.confsched2023.data.contributors
 
 import kotlinx.coroutines.flow.Flow
 
-interface StampRepository {
+public interface StampRepository {
 
-    fun getStampEnabledStream(): Flow<Boolean>
+    public fun getStampEnabledStream(): Flow<Boolean>
 }
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/AboutItem.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/AboutItem.kt
index 62c0b8329..ab7a2e60b 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/AboutItem.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/AboutItem.kt
@@ -1,13 +1,13 @@
 package io.github.droidkaigi.confsched2023.model
 
-sealed class AboutItem {
-    data object Sponsors : AboutItem()
-    data object Contributors : AboutItem()
-    data object Staff : AboutItem()
-    data object CodeOfConduct : AboutItem()
-    data object License : AboutItem()
-    data object PrivacyPolicy : AboutItem()
-    data object YouTube : AboutItem()
-    data object X : AboutItem()
-    data object Medium : AboutItem()
+public sealed class AboutItem {
+    public data object Sponsors : AboutItem()
+    public data object Contributors : AboutItem()
+    public data object Staff : AboutItem()
+    public data object CodeOfConduct : AboutItem()
+    public data object License : AboutItem()
+    public data object PrivacyPolicy : AboutItem()
+    public data object YouTube : AboutItem()
+    public data object X : AboutItem()
+    public data object Medium : AboutItem()
 }
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/ContributorsRepository.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/ContributorsRepository.kt
index ef0c669de..dc13b2a67 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/ContributorsRepository.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/ContributorsRepository.kt
@@ -3,8 +3,8 @@ package io.github.droidkaigi.confsched2023.model
 import kotlinx.collections.immutable.PersistentList
 import kotlinx.coroutines.flow.Flow
 
-interface ContributorsRepository {
+public interface ContributorsRepository {
 
-    fun contributors(): Flow<PersistentList<Contributor>>
-    suspend fun refresh()
+    public fun contributors(): Flow<PersistentList<Contributor>>
+    public suspend fun refresh()
 }
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/DroidKaigi2023Day.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/DroidKaigi2023Day.kt
index 655dc0a2f..d54c5aef8 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/DroidKaigi2023Day.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/DroidKaigi2023Day.kt
@@ -45,7 +45,7 @@ public enum class DroidKaigi2023Day(
     ),
     ;
 
-    fun getDropDownText(language: String): String {
+    public fun getDropDownText(language: String): String {
         val japanese = "ja"
 
         val date = this.start.toLocalDateTime(TimeZone.currentSystemDefault())
@@ -85,7 +85,7 @@ public enum class DroidKaigi2023Day(
         /**
          * @return appropriate initial day for now
          */
-        fun initialSelectedDay(): DroidKaigi2023Day {
+        public fun initialSelectedDay(): DroidKaigi2023Day {
             val reversedEntries = entries.sortedByDescending { it.day }
             var selectedDay = reversedEntries.last()
             for (entry in reversedEntries) {
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/FloorLevel.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/FloorLevel.kt
index 8963a7a73..7a746bd5c 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/FloorLevel.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/FloorLevel.kt
@@ -1,7 +1,7 @@
 package io.github.droidkaigi.confsched2023.model
 
 public enum class FloorLevel(
-    val floorName: String,
+    public val floorName: String,
 ) {
     Basement("B1F"),
     Ground("1F"),
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/RoomType.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/RoomType.kt
index 7edffad9a..e5032ab5e 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/RoomType.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/RoomType.kt
@@ -3,7 +3,7 @@ package io.github.droidkaigi.confsched2023.model
 /**
  * Please use [TimetableRoom] to get room information.
  */
-enum class RoomType {
+public enum class RoomType {
     RoomA,
     RoomB,
     RoomC,
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SessionsRepository.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SessionsRepository.kt
index 425372681..e8eee9c97 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SessionsRepository.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SessionsRepository.kt
@@ -2,8 +2,8 @@ package io.github.droidkaigi.confsched2023.model
 
 import kotlinx.coroutines.flow.Flow
 
-interface SessionsRepository {
-    fun getTimetableStream(): Flow<Timetable>
-    fun getTimetableItemWithBookmarkStream(id: TimetableItemId): Flow<Pair<TimetableItem, Boolean>>
-    suspend fun toggleBookmark(id: TimetableItemId)
+public interface SessionsRepository {
+    public fun getTimetableStream(): Flow<Timetable>
+    public fun getTimetableItemWithBookmarkStream(id: TimetableItemId): Flow<Pair<TimetableItem, Boolean>>
+    public suspend fun toggleBookmark(id: TimetableItemId)
 }
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SideEvent.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SideEvent.kt
index 4f7c9862f..48e36993b 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SideEvent.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/SideEvent.kt
@@ -4,6 +4,7 @@ import io.github.droidkaigi.confsched2023.model.FloorLevel.Basement
 import io.github.droidkaigi.confsched2023.model.FloorLevel.Ground
 import io.github.droidkaigi.confsched2023.model.SideEvent.Mark.Favorite
 import io.github.droidkaigi.confsched2023.model.SideEvent.MarkColor.Pink
+import kotlinx.collections.immutable.PersistentList
 import kotlinx.collections.immutable.persistentListOf
 
 public data class SideEvent(
@@ -16,18 +17,18 @@ public data class SideEvent(
     val imageLink: String?,
 ) {
 
-    enum class Mark(val color: MarkColor) {
+    public enum class Mark(public val color: MarkColor) {
         Favorite(Pink),
     }
 
-    enum class MarkColor {
+    public enum class MarkColor {
         Pink, Orange, Blue, Red, Purple
     }
 
     public companion object
 }
 
-val SideEvents = persistentListOf(
+public val SideEvents: PersistentList<SideEvent> = persistentListOf(
     SideEvent(
         title = MultiLangText(
             jaTitle = "アプリFiresideチャット(これは仮で後で消えます)",
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Staff.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Staff.kt
index b0d776961..e883d1cfa 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Staff.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Staff.kt
@@ -9,11 +9,11 @@ public data class Staff(
     val profileUrl: String,
     val iconUrl: String,
 ) {
-    companion object
+    public companion object
 }
 
 // create fakes
-fun Staff.Companion.fakes(): PersistentList<Staff> {
+public fun Staff.Companion.fakes(): PersistentList<Staff> {
     return (1..20).map {
         Staff(
             id = it.toLong(),
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/StaffRepository.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/StaffRepository.kt
index f8da281ce..d05b0f3a0 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/StaffRepository.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/StaffRepository.kt
@@ -4,7 +4,7 @@ import kotlinx.collections.immutable.PersistentList
 import kotlinx.coroutines.flow.Flow
 import kotlin.coroutines.cancellation.CancellationException
 
-interface StaffRepository {
+public interface StaffRepository {
 
     public fun staffs(): Flow<PersistentList<Staff>>
 
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Stamp.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Stamp.kt
index bb20d522b..538672f4d 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Stamp.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/Stamp.kt
@@ -1,11 +1,11 @@
 package io.github.droidkaigi.confsched2023.model
 
-data class Stamp(
+public data class Stamp(
     val hasDrawableResId: Int,
     val lottieRawId: Int,
     val notHasDrawableResId: Int,
     val hasStamp: Boolean = false,
     val contentDescription: String,
 ) {
-    fun getDrawableResId() = if (hasStamp) hasDrawableResId else notHasDrawableResId
+    public fun getDrawableResId(): Int = if (hasStamp) hasDrawableResId else notHasDrawableResId
 }
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableCategory.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableCategory.kt
index 2607d8f92..58e7631ee 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableCategory.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableCategory.kt
@@ -7,7 +7,7 @@ public data class TimetableCategory(
     public companion object
 }
 
-fun TimetableCategory.Companion.fakes(): List<TimetableCategory> {
+public fun TimetableCategory.Companion.fakes(): List<TimetableCategory> {
     return listOf(
         TimetableCategory(
             id = 1,
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableItem.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableItem.kt
index b1c44241f..229f6f74c 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableItem.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableItem.kt
@@ -92,7 +92,7 @@ public sealed class TimetableItem {
         speakers.joinToString(", ") { it.name }
     }
 
-    fun getSupportedLangString(isJapaneseLocale: Boolean): String {
+    public fun getSupportedLangString(isJapaneseLocale: Boolean): String {
         val japanese = if (isJapaneseLocale) "日本語" else "Japanese"
         val english = if (isJapaneseLocale) "英語" else "English"
         val japaneseWithInterpretation =
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableLanguage.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableLanguage.kt
index 7645a9241..b43cb7b9e 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableLanguage.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableLanguage.kt
@@ -4,7 +4,7 @@ public data class TimetableLanguage(
     val langOfSpeaker: String,
     val isInterpretationTarget: Boolean,
 ) {
-    val labels = if (langOfSpeaker == Lang.MIXED.tagName) {
+    val labels: List<String> = if (langOfSpeaker == Lang.MIXED.tagName) {
         listOf(Lang.MIXED.tagName)
     } else if (isInterpretationTarget) {
         listOf(Lang.ENGLISH.tagName, Lang.JAPANESE.tagName)
@@ -12,7 +12,7 @@ public data class TimetableLanguage(
         listOf(langOfSpeaker.take(2))
     }
 
-    fun toLang() = if (isInterpretationTarget) {
+    public fun toLang(): Lang = if (isInterpretationTarget) {
         Lang.MIXED
     } else {
         Lang.values().firstOrNull { it.tagName == langOfSpeaker.take(2) } ?: Lang.MIXED
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableRoom.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableRoom.kt
index 207490028..28e78a900 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableRoom.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableRoom.kt
@@ -6,7 +6,7 @@ public data class TimetableRoom(
     val type: RoomType,
 )
 
-val TimetableRoom.nameAndFloor: String
+public val TimetableRoom.nameAndFloor: String
     get() {
         val basementFloorString = MultiLangText(jaTitle = "地下1階", enTitle = "B1F")
         val floor = when (type) {
diff --git a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableSessionType.kt b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableSessionType.kt
index c216fd565..afb70f5c1 100644
--- a/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableSessionType.kt
+++ b/core/model/src/commonMain/kotlin/io/github/droidkaigi/confsched2023/model/TimetableSessionType.kt
@@ -1,8 +1,8 @@
 package io.github.droidkaigi.confsched2023.model
 
-enum class TimetableSessionType(
-    val key: String,
-    val label: MultiLangText,
+public enum class TimetableSessionType(
+    public val key: String,
+    public val label: MultiLangText,
 ) {
     WELCOME_TALK(
         key = "WELCOME_TALK",
@@ -34,8 +34,8 @@ enum class TimetableSessionType(
     ),
     ;
 
-    companion object {
-        fun ofOrNull(key: String): TimetableSessionType? {
+    public companion object {
+        public fun ofOrNull(key: String): TimetableSessionType? {
             return values().firstOrNull {
                 it.key == key
             }