diff --git a/backend/pom.xml b/backend/pom.xml
index a5eddab8..81eacb23 100644
--- a/backend/pom.xml
+++ b/backend/pom.xml
@@ -65,6 +65,16 @@
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-jetty</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-testcontainers</artifactId>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.testcontainers</groupId>
+			<artifactId>testcontainers-postgresql</artifactId>
+			<scope>test</scope>
+		</dependency>
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-actuator-test</artifactId>
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/ApplicationContextTest.java b/backend/src/test/java/org/raddatz/familienarchiv/ApplicationContextTest.java
new file mode 100644
index 00000000..899c526c
--- /dev/null
+++ b/backend/src/test/java/org/raddatz/familienarchiv/ApplicationContextTest.java
@@ -0,0 +1,25 @@
+package org.raddatz.familienarchiv;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.springframework.context.annotation.Import;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.context.bean.override.mockito.MockitoBean;
+import org.testcontainers.containers.PostgreSQLContainer;
+import software.amazon.awssdk.services.s3.S3Client;
+
+@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
+@ActiveProfiles("test")
+@Import(PostgresContainerConfig.class)
+class ApplicationContextTest {
+
+    @MockitoBean
+    S3Client s3Client;
+
+    @Test
+    void contextLoads() {
+        // verifies that the Spring context starts successfully with all beans wired,
+        // Flyway migrations applied, and no configuration errors
+    }
+}
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/PostgresContainerConfig.java b/backend/src/test/java/org/raddatz/familienarchiv/PostgresContainerConfig.java
new file mode 100644
index 00000000..20c0697e
--- /dev/null
+++ b/backend/src/test/java/org/raddatz/familienarchiv/PostgresContainerConfig.java
@@ -0,0 +1,16 @@
+package org.raddatz.familienarchiv;
+
+import org.springframework.boot.test.context.TestConfiguration;
+import org.springframework.boot.testcontainers.service.connection.ServiceConnection;
+import org.springframework.context.annotation.Bean;
+import org.testcontainers.containers.PostgreSQLContainer;
+
+@TestConfiguration(proxyBeanMethods = false)
+public class PostgresContainerConfig {
+
+    @Bean
+    @ServiceConnection
+    PostgreSQLContainer<?> postgresContainer() {
+        return new PostgreSQLContainer<>("postgres:16-alpine");
+    }
+}
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/repository/DocumentRepositoryTest.java b/backend/src/test/java/org/raddatz/familienarchiv/repository/DocumentRepositoryTest.java
new file mode 100644
index 00000000..0a960117
--- /dev/null
+++ b/backend/src/test/java/org/raddatz/familienarchiv/repository/DocumentRepositoryTest.java
@@ -0,0 +1,150 @@
+package org.raddatz.familienarchiv.repository;
+
+import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.PostgresContainerConfig;
+import org.raddatz.familienarchiv.config.FlywayConfig;
+import org.raddatz.familienarchiv.model.Document;
+import org.raddatz.familienarchiv.model.DocumentStatus;
+import org.raddatz.familienarchiv.model.Person;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.jdbc.test.autoconfigure.AutoConfigureTestDatabase;
+import org.springframework.boot.data.jpa.test.autoconfigure.DataJpaTest;
+import org.springframework.context.annotation.Import;
+
+import java.util.List;
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DataJpaTest
+@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
+@Import({PostgresContainerConfig.class, FlywayConfig.class})
+class DocumentRepositoryTest {
+
+    @Autowired
+    private DocumentRepository documentRepository;
+
+    @Autowired
+    private PersonRepository personRepository;
+
+    // ─── save and findById ────────────────────────────────────────────────────
+
+    @Test
+    void save_persistsDocument_andFindByIdReturnsSameDocument() {
+        Document document = Document.builder()
+                .title("Testbrief")
+                .originalFilename("testbrief.pdf")
+                .status(DocumentStatus.PLACEHOLDER)
+                .build();
+
+        Document saved = documentRepository.save(document);
+        Optional<Document> found = documentRepository.findById(saved.getId());
+
+        assertThat(found).isPresent();
+        assertThat(found.get().getTitle()).isEqualTo("Testbrief");
+        assertThat(found.get().getStatus()).isEqualTo(DocumentStatus.PLACEHOLDER);
+    }
+
+    // ─── findByStatus ─────────────────────────────────────────────────────────
+
+    @Test
+    void findByStatus_returnsOnlyDocumentsWithMatchingStatus() {
+        documentRepository.save(Document.builder()
+                .title("Placeholder Doc")
+                .originalFilename("placeholder.pdf")
+                .status(DocumentStatus.PLACEHOLDER)
+                .build());
+        documentRepository.save(Document.builder()
+                .title("Uploaded Doc")
+                .originalFilename("uploaded.pdf")
+                .status(DocumentStatus.UPLOADED)
+                .build());
+
+        List<Document> placeholders = documentRepository.findByStatus(DocumentStatus.PLACEHOLDER);
+
+        assertThat(placeholders).extracting(Document::getStatus)
+                .containsOnly(DocumentStatus.PLACEHOLDER);
+    }
+
+    // ─── findByOriginalFilename ───────────────────────────────────────────────
+
+    @Test
+    void findByOriginalFilename_returnsDocument_whenFilenameMatches() {
+        documentRepository.save(Document.builder()
+                .title("Omas Brief")
+                .originalFilename("omas_brief.pdf")
+                .status(DocumentStatus.PLACEHOLDER)
+                .build());
+
+        Optional<Document> found = documentRepository.findByOriginalFilename("omas_brief.pdf");
+
+        assertThat(found).isPresent();
+        assertThat(found.get().getTitle()).isEqualTo("Omas Brief");
+    }
+
+    @Test
+    void findByOriginalFilename_returnsEmpty_whenFilenameDoesNotExist() {
+        Optional<Document> found = documentRepository.findByOriginalFilename("does_not_exist.pdf");
+
+        assertThat(found).isEmpty();
+    }
+
+    // ─── existsByOriginalFilename ─────────────────────────────────────────────
+
+    @Test
+    void existsByOriginalFilename_returnsTrue_whenDocumentExists() {
+        documentRepository.save(Document.builder()
+                .title("Brief")
+                .originalFilename("brief.pdf")
+                .status(DocumentStatus.PLACEHOLDER)
+                .build());
+
+        assertThat(documentRepository.existsByOriginalFilename("brief.pdf")).isTrue();
+    }
+
+    @Test
+    void existsByOriginalFilename_returnsFalse_whenDocumentDoesNotExist() {
+        assertThat(documentRepository.existsByOriginalFilename("nonexistent.pdf")).isFalse();
+    }
+
+    // ─── findBySenderId ───────────────────────────────────────────────────────
+
+    @Test
+    void findBySenderId_returnsDocuments_whereSenderIdMatches() {
+        Person sender = personRepository.save(Person.builder()
+                .firstName("Hans")
+                .lastName("Müller")
+                .build());
+        documentRepository.save(Document.builder()
+                .title("Brief von Hans")
+                .originalFilename("brief_hans.pdf")
+                .status(DocumentStatus.UPLOADED)
+                .sender(sender)
+                .build());
+
+        List<Document> docs = documentRepository.findBySenderId(sender.getId());
+
+        assertThat(docs).hasSize(1);
+        assertThat(docs.get(0).getSender().getId()).isEqualTo(sender.getId());
+    }
+
+    // ─── countByMetadataCompleteFalse ─────────────────────────────────────────
+
+    @Test
+    void countByMetadataCompleteFalse_returnsNumberOfIncompleteDocuments() {
+        documentRepository.save(Document.builder()
+                .title("Incomplete")
+                .originalFilename("incomplete.pdf")
+                .status(DocumentStatus.PLACEHOLDER)
+                .metadataComplete(false)
+                .build());
+        documentRepository.save(Document.builder()
+                .title("Complete")
+                .originalFilename("complete.pdf")
+                .status(DocumentStatus.UPLOADED)
+                .metadataComplete(true)
+                .build());
+
+        assertThat(documentRepository.countByMetadataCompleteFalse()).isEqualTo(1);
+    }
+}
diff --git a/backend/src/test/java/org/raddatz/familienarchiv/repository/PersonRepositoryTest.java b/backend/src/test/java/org/raddatz/familienarchiv/repository/PersonRepositoryTest.java
new file mode 100644
index 00000000..8ed8fb09
--- /dev/null
+++ b/backend/src/test/java/org/raddatz/familienarchiv/repository/PersonRepositoryTest.java
@@ -0,0 +1,136 @@
+package org.raddatz.familienarchiv.repository;
+
+import org.junit.jupiter.api.Test;
+import org.raddatz.familienarchiv.PostgresContainerConfig;
+import org.raddatz.familienarchiv.config.FlywayConfig;
+import org.raddatz.familienarchiv.model.Person;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.jdbc.test.autoconfigure.AutoConfigureTestDatabase;
+import org.springframework.boot.data.jpa.test.autoconfigure.DataJpaTest;
+import org.springframework.context.annotation.Import;
+
+import java.util.List;
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@DataJpaTest
+@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
+@Import({PostgresContainerConfig.class, FlywayConfig.class})
+class PersonRepositoryTest {
+
+    @Autowired
+    private PersonRepository personRepository;
+
+    // ─── save and findById ────────────────────────────────────────────────────
+
+    @Test
+    void save_persistsPerson_andFindByIdReturnsSamePerson() {
+        Person person = Person.builder()
+                .firstName("Anna")
+                .lastName("Schmidt")
+                .build();
+
+        Person saved = personRepository.save(person);
+        Optional<Person> found = personRepository.findById(saved.getId());
+
+        assertThat(found).isPresent();
+        assertThat(found.get().getFirstName()).isEqualTo("Anna");
+        assertThat(found.get().getLastName()).isEqualTo("Schmidt");
+    }
+
+    // ─── searchByName ─────────────────────────────────────────────────────────
+
+    @Test
+    void searchByName_findsByFirstName() {
+        personRepository.save(Person.builder().firstName("Hans").lastName("Müller").build());
+        personRepository.save(Person.builder().firstName("Anna").lastName("Schmidt").build());
+
+        List<Person> results = personRepository.searchByName("Hans");
+
+        assertThat(results).hasSize(1);
+        assertThat(results.get(0).getFirstName()).isEqualTo("Hans");
+    }
+
+    @Test
+    void searchByName_findsByLastName() {
+        personRepository.save(Person.builder().firstName("Hans").lastName("Müller").build());
+        personRepository.save(Person.builder().firstName("Anna").lastName("Schmidt").build());
+
+        List<Person> results = personRepository.searchByName("Schmidt");
+
+        assertThat(results).hasSize(1);
+        assertThat(results.get(0).getLastName()).isEqualTo("Schmidt");
+    }
+
+    @Test
+    void searchByName_isCaseInsensitive() {
+        personRepository.save(Person.builder().firstName("Hans").lastName("Müller").build());
+
+        List<Person> results = personRepository.searchByName("hans");
+
+        assertThat(results).hasSize(1);
+    }
+
+    @Test
+    void searchByName_findsByAlias() {
+        personRepository.save(Person.builder()
+                .firstName("Hans").lastName("Müller").alias("Opa Hans").build());
+
+        List<Person> results = personRepository.searchByName("Opa Hans");
+
+        assertThat(results).hasSize(1);
+    }
+
+    // ─── findAllByOrderByLastNameAscFirstNameAsc ──────────────────────────────
+
+    @Test
+    void findAllByOrderByLastNameAscFirstNameAsc_returnsSortedByLastNameThenFirstName() {
+        personRepository.save(Person.builder().firstName("Bernd").lastName("Ziegler").build());
+        personRepository.save(Person.builder().firstName("Anna").lastName("Müller").build());
+        personRepository.save(Person.builder().firstName("Clara").lastName("Müller").build());
+
+        List<Person> sorted = personRepository.findAllByOrderByLastNameAscFirstNameAsc();
+
+        assertThat(sorted).extracting(Person::getLastName)
+                .startsWith("Müller", "Müller");
+        assertThat(sorted.stream()
+                .filter(p -> p.getLastName().equals("Müller"))
+                .map(Person::getFirstName)
+                .toList())
+                .containsExactly("Anna", "Clara");
+    }
+
+    // ─── findByAliasIgnoreCase ────────────────────────────────────────────────
+
+    @Test
+    void findByAliasIgnoreCase_returnsMatchingPerson() {
+        personRepository.save(Person.builder()
+                .firstName("Karl").lastName("Brandt").alias("Opa Karl").build());
+
+        Optional<Person> found = personRepository.findByAliasIgnoreCase("opa karl");
+
+        assertThat(found).isPresent();
+        assertThat(found.get().getFirstName()).isEqualTo("Karl");
+    }
+
+    @Test
+    void findByAliasIgnoreCase_returnsEmpty_whenAliasDoesNotMatch() {
+        Optional<Person> found = personRepository.findByAliasIgnoreCase("nobody");
+
+        assertThat(found).isEmpty();
+    }
+
+    // ─── findByFirstNameIgnoreCaseAndLastNameIgnoreCase ───────────────────────
+
+    @Test
+    void findByFirstNameIgnoreCaseAndLastNameIgnoreCase_returnsMatch() {
+        personRepository.save(Person.builder().firstName("Maria").lastName("Raddatz").build());
+
+        Optional<Person> found = personRepository.findByFirstNameIgnoreCaseAndLastNameIgnoreCase(
+                "maria", "raddatz");
+
+        assertThat(found).isPresent();
+        assertThat(found.get().getFirstName()).isEqualTo("Maria");
+    }
+}
diff --git a/backend/src/test/resources/application-test.yaml b/backend/src/test/resources/application-test.yaml
new file mode 100644
index 00000000..6a8cbad3
--- /dev/null
+++ b/backend/src/test/resources/application-test.yaml
@@ -0,0 +1,15 @@
+app:
+  s3:
+    endpoint: http://localhost:9000
+    access-key: dummy
+    secret-key: dummy
+    bucket: test-bucket
+    region: us-east-1
+
+spring:
+  datasource:
+    url: will-be-overridden-by-testcontainers
+    username: test
+    password: test
+  mail:
+    host: localhost