diff --git a/app/build.gradle b/app/build.gradle
index 01dc1b9..72ed13b 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -50,6 +50,7 @@ dependencies {
     implementation 'com.beust:klaxon:5.0.1'
     implementation 'com.squareup.okhttp3:okhttp:4.3.0'
     implementation 'com.google.android.material:material:1.1.0-beta02'
+    implementation 'net.swiftzer.semver:semver:1.1.0'
     implementation 'io.sentry:sentry-android:1.7.27'
     implementation 'org.slf4j:slf4j-nop:1.7.25'
     implementation 'com.google.android.gms:play-services-analytics:10.2.4'
diff --git a/app/src/main/java/tech/httptoolkit/android/HttpToolkitApplication.kt b/app/src/main/java/tech/httptoolkit/android/HttpToolkitApplication.kt
index fdb2042..340e582 100644
--- a/app/src/main/java/tech/httptoolkit/android/HttpToolkitApplication.kt
+++ b/app/src/main/java/tech/httptoolkit/android/HttpToolkitApplication.kt
@@ -1,6 +1,7 @@
 package tech.httptoolkit.android
 
 import android.app.Application
+import android.content.Context
 import android.util.Log
 import com.android.installreferrer.api.InstallReferrerClient
 import com.android.installreferrer.api.InstallReferrerClient.InstallReferrerResponse
@@ -11,10 +12,17 @@ import com.google.android.gms.analytics.HitBuilders
 import com.google.android.gms.analytics.Tracker
 import io.sentry.Sentry
 import io.sentry.android.AndroidSentryClientFactory
+import kotlinx.coroutines.*
+import net.swiftzer.semver.SemVer
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import java.text.SimpleDateFormat
+import java.util.*
 import java.util.concurrent.atomic.AtomicBoolean
 import kotlin.coroutines.resume
 import kotlin.coroutines.suspendCoroutine
 
+
 class HttpToolkitApplication : Application() {
 
     private val TAG = HttpToolkitApplication::class.simpleName
@@ -149,4 +157,87 @@ class HttpToolkitApplication : Application() {
         analytics?.setLocalDispatchPeriod(120) // Set dispatching back to Android default
     }
 
+    suspend fun isUpdateRequired(): Boolean {
+        return withContext(Dispatchers.IO) {
+            if (wasInstalledFromStore(this@HttpToolkitApplication)) {
+                // We only check for updates for side-loaded/ADB-loaded versions. This is useful
+                // because otherwise anything outside the play store gets no updates.
+                Log.i(TAG, "Installed from play store, no update prompting required")
+                return@withContext false
+            }
+
+            val httpClient = OkHttpClient()
+            val request = Request.Builder()
+                .url("https://api.github.com/repos/httptoolkit/httptoolkit-android/releases/latest")
+                .build()
+
+            try {
+                val response = httpClient.newCall(request).execute().use { response ->
+                    if (response.code != 200) throw RuntimeException("Failed to check for updates")
+                    response.body!!.string()
+                }
+
+                val release = Klaxon().parse<GithubRelease>(response)!!
+                val releaseVersion =
+                    tryParseSemver(release.name)
+                    ?: tryParseSemver(release.tag_name)
+                    ?: throw RuntimeException("Could not parse release version ${release.tag_name}")
+                val releaseDate = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss").parse(release.published_at)
+
+                val installedVersion = getInstalledVersion(this@HttpToolkitApplication)
+
+                val updateAvailable = releaseVersion > installedVersion
+                // We avoid immediately prompting for updates because a) there's a review delay
+                // before new updates go live, and b) it's annoying otherwise, if there's a rapid
+                // series of releases. Better to start chasing users only after a week stable.
+                val updateNotTooRecent = releaseDate.before(daysAgo(0))
+
+                Log.i(TAG,
+                    if (updateAvailable && updateNotTooRecent)
+                        "New version available, released > 1 week"
+                    else if (updateAvailable)
+                        "New version available, but still recent, released $releaseDate"
+                    else
+                        "App is up to date"
+                )
+                return@withContext updateAvailable && updateNotTooRecent
+            } catch (e: Exception) {
+                Log.w(TAG, e)
+                return@withContext false
+            }
+        }
+    }
+
+}
+
+private fun wasInstalledFromStore(context: Context): Boolean {
+    return context.packageManager.getInstallerPackageName(context.packageName) != null
+}
+
+private data class GithubRelease(
+    val tag_name: String?,
+    val name: String?,
+    val published_at: String
+)
+
+private fun tryParseSemver(version: String?): SemVer? = try {
+    if (version == null) null
+    else SemVer.parse(
+        // Strip leading 'v'
+        version.replace(Regex("^v"), "")
+    )
+} catch (e: IllegalArgumentException) {
+    null
+}
+
+private fun getInstalledVersion(context: Context): SemVer {
+    return SemVer.parse(
+        context.packageManager.getPackageInfo(context.packageName, 0).versionName
+    )
+}
+
+private fun daysAgo(days: Int): Date {
+    val calendar = Calendar.getInstance()
+    calendar.add(Calendar.DAY_OF_YEAR, -days)
+    return calendar.time
 }
\ No newline at end of file
diff --git a/app/src/main/java/tech/httptoolkit/android/MainActivity.kt b/app/src/main/java/tech/httptoolkit/android/MainActivity.kt
index 3cc12b0..d4993df 100644
--- a/app/src/main/java/tech/httptoolkit/android/MainActivity.kt
+++ b/app/src/main/java/tech/httptoolkit/android/MainActivity.kt
@@ -4,6 +4,7 @@ import android.content.BroadcastReceiver
 import android.content.Context
 import android.content.Intent
 import android.content.IntentFilter
+import android.content.pm.PackageManager
 import android.net.Uri
 import android.net.VpnService
 import android.os.Bundle
@@ -18,6 +19,7 @@ import android.widget.TextView
 import androidx.annotation.StringRes
 import androidx.appcompat.app.AppCompatActivity
 import androidx.localbroadcastmanager.content.LocalBroadcastManager
+import com.google.android.gms.common.GooglePlayServicesUtil
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import io.sentry.Sentry
 import kotlinx.coroutines.*
@@ -94,6 +96,13 @@ class MainActivity : AppCompatActivity(), CoroutineScope by MainScope() {
                 }
             }
         }
+
+        // Async check for updates, and maybe prompt the user if necessary (if using play store)
+        launch {
+            supervisorScope {
+                if (isStoreAvailable(this@MainActivity) && app.isUpdateRequired()) promptToUpdate()
+            }
+        }
     }
 
     override fun onResume() {
@@ -460,4 +469,31 @@ class MainActivity : AppCompatActivity(), CoroutineScope by MainScope() {
         }
     }
 
+    private suspend fun promptToUpdate() {
+        withContext(Dispatchers.Main) {
+            MaterialAlertDialogBuilder(this@MainActivity)
+                .setTitle("Updates available")
+                .setIcon(R.drawable.ic_info_circle)
+                .setMessage("An updated version of HTTP Toolkit is available")
+                .setNegativeButton("Ignore") { _, _ -> }
+                .setPositiveButton("Update now") { _, _ ->
+                    // Open the app in the market. That a release is available on github doesn't
+                    // *strictly* mean that it's available on the Android market right now, but
+                    // it is imminent, and installing from play means it'll update fully later.
+                    startActivity(
+                        Intent(Intent.ACTION_VIEW).apply {
+                            data = Uri.parse("market://details?id=tech.httptoolkit.android.v1")
+                        }
+                    )
+                }
+                .show()
+        }
+    }
+}
+
+private fun isStoreAvailable(context: Context): Boolean = try {
+    context.packageManager.getPackageInfo(GooglePlayServicesUtil.GOOGLE_PLAY_STORE_PACKAGE, 0)
+    true
+} catch (e: PackageManager.NameNotFoundException) {
+    false
 }
\ No newline at end of file