diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/CandidateMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/CandidateMapper.java
new file mode 100644
index 0000000..8479f4f
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/CandidateMapper.java
@@ -0,0 +1,26 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.db.Candidate;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface CandidateMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.Candidate mapToExternal(Candidate candidate);
+
+  de.twomartens.wahlrecht.model.internal.Candidate mapToInternal(
+      de.twomartens.wahlrecht.model.dto.v1.Candidate candidate);
+
+  de.twomartens.wahlrecht.model.internal.Candidate mapToInternal(Candidate candidate);
+
+  @Mapping(target = "id", ignore = true)
+  @Mapping(target = "created", ignore = true)
+  @Mapping(target = "lastModified", ignore = true)
+  Candidate mapToDB(de.twomartens.wahlrecht.model.dto.v1.Candidate candidate);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ConstituencyMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ConstituencyMapper.java
new file mode 100644
index 0000000..e1b6c52
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ConstituencyMapper.java
@@ -0,0 +1,26 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.db.Constituency;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ConstituencyMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.Constituency mapToExternal(Constituency constituency);
+
+  de.twomartens.wahlrecht.model.internal.Constituency mapToInternal(
+      de.twomartens.wahlrecht.model.dto.v1.Constituency constituency);
+
+  de.twomartens.wahlrecht.model.internal.Constituency mapToInternal(Constituency constituency);
+
+  @Mapping(target = "id", ignore = true)
+  @Mapping(target = "created", ignore = true)
+  @Mapping(target = "lastModified", ignore = true)
+  Constituency mapToDB(de.twomartens.wahlrecht.model.dto.v1.Constituency constituency);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedCandidateMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedCandidateMapper.java
new file mode 100644
index 0000000..e46b18a
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedCandidateMapper.java
@@ -0,0 +1,17 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.internal.ElectedCandidate;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ElectedCandidateMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.ElectedCandidate mapToExternal(ElectedCandidate candidate);
+
+  ElectedCandidate mapToInternal(de.twomartens.wahlrecht.model.dto.v1.ElectedCandidate candidate);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedMapper.java
new file mode 100644
index 0000000..3e7fc75
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedMapper.java
@@ -0,0 +1,17 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.internal.Elected;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ElectedMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.Elected mapToExternal(Elected elected);
+
+  Elected mapToInternal(de.twomartens.wahlrecht.model.dto.v1.Elected elected);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedResultMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedResultMapper.java
new file mode 100644
index 0000000..91ae57a
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectedResultMapper.java
@@ -0,0 +1,35 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.dto.v1.ElectedCandidate;
+import de.twomartens.wahlrecht.model.dto.v1.VotingResult;
+import de.twomartens.wahlrecht.model.internal.ElectedResult;
+import java.util.Collection;
+import java.util.Map;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ElectedResultMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.ElectedResult mapToExternal(ElectedResult result);
+
+  Map<VotingResult, Collection<ElectedCandidate>> mapToExternal(
+      Map<de.twomartens.wahlrecht.model.internal.VotingResult,
+          Collection<de.twomartens.wahlrecht.model.internal.ElectedCandidate>> value);
+
+  Collection<ElectedCandidate> mapToExternal(
+      Collection<de.twomartens.wahlrecht.model.internal.ElectedCandidate> value);
+
+  ElectedResult mapToInternal(de.twomartens.wahlrecht.model.dto.v1.ElectedResult result);
+
+  Map<de.twomartens.wahlrecht.model.internal.VotingResult,
+      Collection<de.twomartens.wahlrecht.model.internal.ElectedCandidate>> mapToInternal(
+      Map<VotingResult, Collection<ElectedCandidate>> value);
+
+  Collection<de.twomartens.wahlrecht.model.internal.ElectedCandidate> mapToInternal(
+      Collection<ElectedCandidate> value);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectionMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectionMapper.java
new file mode 100644
index 0000000..d7d4299
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/ElectionMapper.java
@@ -0,0 +1,26 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.db.Election;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface ElectionMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.Election mapToExternal(Election election);
+
+  de.twomartens.wahlrecht.model.internal.Election mapToInternal(
+      de.twomartens.wahlrecht.model.dto.v1.Election election);
+
+  de.twomartens.wahlrecht.model.internal.Election mapToInternal(Election election);
+
+  @Mapping(target = "id", ignore = true)
+  @Mapping(target = "created", ignore = true)
+  @Mapping(target = "lastModified", ignore = true)
+  Election mapToDB(de.twomartens.wahlrecht.model.dto.v1.Election election);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/NominationMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/NominationMapper.java
new file mode 100644
index 0000000..f8a168a
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/NominationMapper.java
@@ -0,0 +1,30 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.db.Nomination;
+import de.twomartens.wahlrecht.model.internal.Candidate;
+import java.util.Collection;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface NominationMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.Nomination mapToExternal(Nomination nomination);
+
+  de.twomartens.wahlrecht.model.internal.Nomination mapToInternal(
+      de.twomartens.wahlrecht.model.dto.v1.Nomination nomination);
+
+  de.twomartens.wahlrecht.model.internal.Nomination mapToInternal(Nomination nomination);
+
+  @Mapping(target = "id", ignore = true)
+  @Mapping(target = "created", ignore = true)
+  @Mapping(target = "lastModified", ignore = true)
+  Nomination mapToDB(de.twomartens.wahlrecht.model.dto.v1.Nomination nomination);
+
+  Collection<Candidate> map(Collection<de.twomartens.wahlrecht.model.db.Candidate> candidates);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/PartyInElectionMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/PartyInElectionMapper.java
new file mode 100644
index 0000000..33245b1
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/PartyInElectionMapper.java
@@ -0,0 +1,21 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.db.PartyInElection;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.Mapping;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface PartyInElectionMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.PartyInElection mapToExternal(PartyInElection election);
+
+  @Mapping(target = "id", ignore = true)
+  @Mapping(target = "created", ignore = true)
+  @Mapping(target = "lastModified", ignore = true)
+  PartyInElection mapToDB(de.twomartens.wahlrecht.model.dto.v1.PartyInElection election);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/SeatResultMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/SeatResultMapper.java
new file mode 100644
index 0000000..4cc6c7b
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/SeatResultMapper.java
@@ -0,0 +1,19 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.internal.SeatResult;
+import java.util.Deque;
+import java.util.LinkedList;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface SeatResultMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.SeatResult mapToExternal(SeatResult result);
+
+  SeatResult mapToInternal(de.twomartens.wahlrecht.model.dto.v1.SeatResult result);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingResultMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingResultMapper.java
new file mode 100644
index 0000000..e6c70a4
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingResultMapper.java
@@ -0,0 +1,17 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.internal.VotingResult;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface VotingResultMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.VotingResult mapToExternal(VotingResult result);
+
+  VotingResult mapToInternal(de.twomartens.wahlrecht.model.dto.v1.VotingResult result);
+}
diff --git a/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingThresholdMapper.java b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingThresholdMapper.java
new file mode 100644
index 0000000..8975098
--- /dev/null
+++ b/module-server/src/main/java/de/twomartens/wahlrecht/mapper/v1/VotingThresholdMapper.java
@@ -0,0 +1,17 @@
+package de.twomartens.wahlrecht.mapper.v1;
+
+import de.twomartens.wahlrecht.model.internal.VotingThreshold;
+import org.mapstruct.CollectionMappingStrategy;
+import org.mapstruct.Mapper;
+import org.mapstruct.NullValueCheckStrategy;
+import org.mapstruct.ReportingPolicy;
+
+@Mapper(collectionMappingStrategy = CollectionMappingStrategy.ADDER_PREFERRED,
+    nullValueCheckStrategy = NullValueCheckStrategy.ALWAYS,
+    unmappedTargetPolicy = ReportingPolicy.IGNORE)
+public interface VotingThresholdMapper {
+
+  de.twomartens.wahlrecht.model.dto.v1.VotingThreshold mapToExternal(VotingThreshold threshold);
+
+  VotingThreshold mapToInternal(de.twomartens.wahlrecht.model.dto.v1.VotingThreshold threshold);
+}