diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterDuplicates.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterDuplicates.kt
index c9ac3732f..399023118 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterDuplicates.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterDuplicates.kt
@@ -5,6 +5,11 @@ import app.ehrenamtskarte.backend.stores.importer.logRemoveDuplicates
 import app.ehrenamtskarte.backend.stores.importer.types.AcceptingStore
 import org.slf4j.Logger
 
+/**
+ * Filters and removes duplicates.
+ * For duplicates to be detected an exact match of name, postal code and street is necessary.
+ * The properties of the last accepting store are used if there are multiple valid properties.
+ */
 class FilterDuplicates(private val logger: Logger) : PipelineStep<List<AcceptingStore>, List<AcceptingStore>>() {
 
     override fun execute(input: List<AcceptingStore>): List<AcceptingStore> {
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterLbe.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterLbe.kt
index 15f5e95b8..a4b8cd165 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterLbe.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/FilterLbe.kt
@@ -7,6 +7,10 @@ import app.ehrenamtskarte.backend.stores.importer.matchesNa
 import app.ehrenamtskarte.backend.stores.importer.types.LbeAcceptingStore
 import org.slf4j.Logger
 
+/**
+ * Filter and removes [LbeAcceptingStore] with invalid data.
+ * These are especially stores without name, location or an invalid category.
+ */
 class FilterLbe(private val logger: Logger): PipelineStep<List<LbeAcceptingStore>, List<LbeAcceptingStore>>() {
     private val invalidLocations = arrayOf("Musterhausen")
 
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/MapFromLbe.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/MapFromLbe.kt
index b95ecf0f1..7a93ca58a 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/MapFromLbe.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/MapFromLbe.kt
@@ -10,7 +10,12 @@ import app.ehrenamtskarte.backend.stores.importer.types.LbeAcceptingStore
 import org.apache.commons.text.StringEscapeUtils
 import org.slf4j.Logger
 
+/**
+ * Maps [LbeAcceptingStore] to [AcceptingStore].
+ * Properties are cleaned, decoded and converted to the correct types.
+ */
 class MapFromLbe(private val logger: Logger) : PipelineStep<List<LbeAcceptingStore>, List<AcceptingStore>>() {
+
     override fun execute(input: List<LbeAcceptingStore>) = input.mapNotNull {
         try {
             AcceptingStore(
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/PostSanitizeFilter.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/PostSanitizeFilter.kt
index 9475164ec..4f15e7425 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/PostSanitizeFilter.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/PostSanitizeFilter.kt
@@ -9,6 +9,10 @@ import io.ktor.client.*
 import kotlinx.coroutines.runBlocking
 import org.slf4j.Logger
 
+/**
+ * Filters [AcceptingStore] to prepare storing to the database.
+ * Stores without longitude, latitude or postal code or outside the states bounding box are removed.
+ */
 class PostSanitizeFilter(private val logger: Logger, httpClient: HttpClient): PipelineStep<List<AcceptingStore>, List<AcceptingStore>>() {
     private val featureFetcher = FeatureFetcher(httpClient)
 
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeAddress.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeAddress.kt
index 3be42a6c9..624720d74 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeAddress.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeAddress.kt
@@ -7,6 +7,11 @@ import app.ehrenamtskarte.backend.stores.importer.types.AcceptingStore
 import org.intellij.lang.annotations.Language
 import org.slf4j.Logger
 
+/**
+ * Sanitizes the addresses of the [AcceptingStore].
+ * Postal codes are mapped to either the first five digits (german postcode format) or null.
+ * Street and house numbers are correctly separated.
+ */
 class SanitizeAddress(private val logger: Logger) : PipelineStep<List<AcceptingStore>, List<AcceptingStore>>() {
     private val houseNumberRegex = houseNumberRegex()
     private val postalCodeRegex = Regex("""[0-9]{5}""")
@@ -42,6 +47,12 @@ class SanitizeAddress(private val logger: Logger) : PipelineStep<List<AcceptingS
         return Regex("""$prefix[0-9]+(($range)|($fraction)|($letter))?""")
     }
 
+    /**
+     * Correctly separates the street and house number properties.
+     * Excess information is moved to the [AcceptingStore.additionalAddressInformation] property.
+     * Examples: 'Untere'|'Zell' -> 'Untere Zell'|null, 'Am Römerbad 17'|'a' -> 'Am Römerbad'|'17 a',
+     *   'Rückermainstr. 2; 1.'|'OG' -> 'Rückermainstr.'|'2'|'1. OG'
+     */
     private fun AcceptingStore.sanitizeStreetHouseNumber(): AcceptingStore {
         val isStreetPolluted = street?.find { it.isDigit() } != null
         val isHouseNumberPolluted = houseNumber != null && !houseNumberRegex.matches(houseNumber)
@@ -73,6 +84,10 @@ class SanitizeAddress(private val logger: Logger) : PipelineStep<List<AcceptingS
         return this
     }
 
+    /**
+     * Maps the postal code to the first five digits or null.
+     * Examples: '86150' -> '86150', 'Augsburg 86161 Rathausplatz' -> '86161', 'A-1234' -> null
+     */
     private fun AcceptingStore.sanitizePostalCode(): AcceptingStore {
         val oldPostalCode = postalCode ?: return this
 
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeGeocode.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeGeocode.kt
index cd79003ba..a2bdabed9 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeGeocode.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/SanitizeGeocode.kt
@@ -13,6 +13,11 @@ import org.geojson.Feature
 import org.geojson.Point
 import org.slf4j.Logger
 
+/**
+ * Sanitize the postal code and the coordinates of the [AcceptingStore] using forward geocoding.
+ * If the coordinates are not inside the bounding box of the postal code, one of those is wrong.
+ * Then query by the address and use the coordinates OR postal code of the first match to sanitize the store data.
+ */
 class SanitizeGeocode(private val logger: Logger, httpClient: HttpClient) : PipelineStep<List<AcceptingStore>, List<AcceptingStore>>() {
     private val featureFetcher = FeatureFetcher(httpClient)
 
@@ -20,11 +25,6 @@ class SanitizeGeocode(private val logger: Logger, httpClient: HttpClient) : Pipe
         input.map { it.sanitize() }
     }
 
-    /**
-     * Sanitize the postal code and the coordinates of the [AcceptingStore] using forward geocoding.
-     * If the coordinates are not inside the bounding box of the postal code, one of those is wrong.
-     * Then query by the address and use the coordinates OR postal code of the first match to sanitize the store data.
-     */
     private suspend fun AcceptingStore.sanitize(): AcceptingStore {
         if (street?.contains(STREET_EXCLUDE_PATTERN) == true) return this
 
diff --git a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/Store.kt b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/Store.kt
index c54c867ff..cba850c99 100644
--- a/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/Store.kt
+++ b/backend/src/main/kotlin/app/ehrenamtskarte/backend/stores/importer/steps/Store.kt
@@ -9,6 +9,10 @@ import org.jetbrains.exposed.sql.transactions.transaction
 import org.postgis.Point
 import org.slf4j.Logger
 
+/**
+ * Stores the given [AcceptingStore] to the database.
+ * Longitude, latitude and postal code of [AcceptingStore] must not be null.
+ */
 class Store(private val logger: Logger, private val manualImport: Boolean) : PipelineStep<List<AcceptingStore>, Unit>() {
 
     override fun execute(input: List<AcceptingStore>) {
@@ -20,13 +24,9 @@ class Store(private val logger: Logger, private val manualImport: Boolean) : Pip
                 Addresses.deleteAll()
 
                 input.forEachIndexed { done, acceptingStore ->
-                    if (acceptingStore.postalCode == null) {
-                        logger.info("Skipping '${acceptingStore.name}' because its postal code is null.")
-                        return@forEachIndexed
-                    }
                     val address = AddressEntity.new {
                         street = acceptingStore.streetWithHouseNumber
-                        postalCode = acceptingStore.postalCode
+                        postalCode = acceptingStore.postalCode!!
                         locaction = acceptingStore.location
                         countryCode = acceptingStore.countryCode
                     }