diff --git a/pom.xml b/pom.xml
index 53655871..1a0f6740 100644
--- a/pom.xml
+++ b/pom.xml
@@ -128,5 +128,15 @@
 			<artifactId>hamcrest-library</artifactId>
 			<version>1.3</version>
 		</dependency>
+	 <dependency>
+	  <groupId>org.glassfish.jersey.media</groupId>
+	  <artifactId>jersey-media-multipart</artifactId>
+	  <version>2.27</version>
+	 </dependency>
+	 <dependency>
+	  <groupId>javax.mail</groupId>
+	  <artifactId>mail</artifactId>
+	  <version>1.5.0-b01</version>
+	 </dependency>
 	</dependencies>
 </project>
\ No newline at end of file
diff --git a/src/Start.java b/src/Start.java
index 585f65c6..cbab3830 100644
--- a/src/Start.java
+++ b/src/Start.java
@@ -8,7 +8,7 @@ import repository.hsqldb.HSQLDBRepositoryFactory;
 
 public class Start {
 
-	private static final String connectionUrl = "jdbc:hsqldb:mem:db/test;create=true;close_result=true;sql.strict_exec=true;sql.enforce_names=true;sql.syntax_mys=true";
+	private static final String connectionUrl = "jdbc:hsqldb:file:db/test;create=true";
 
 	public static void main(String args[]) throws DataException {
 		RepositoryFactory repositoryFactory = new HSQLDBRepositoryFactory(connectionUrl);
@@ -19,7 +19,7 @@ public class Start {
 
 		//// testing the API client
 		//ApiClient client = ApiClient.getInstance();
-		//String test = client.executeCommand("GET blocks/height");
+		//String test = client.executeCommand("GET blocks/first");
 		//System.out.println(test);
 	}
 }
diff --git a/src/api/BlocksResource.java b/src/api/BlocksResource.java
index 5367b999..74db659c 100644
--- a/src/api/BlocksResource.java
+++ b/src/api/BlocksResource.java
@@ -1,5 +1,6 @@
 package api;
 
+import data.block.BlockData;
 import globalization.Translator;
 import io.swagger.v3.oas.annotations.OpenAPIDefinition;
 import io.swagger.v3.oas.annotations.Operation;
@@ -19,6 +20,7 @@ import javax.ws.rs.core.MediaType;
 
 import repository.Repository;
 import repository.RepositoryManager;
+import utils.Base58;
 
 @Path("blocks")
 @Produces({MediaType.APPLICATION_JSON, MediaType.TEXT_PLAIN})
@@ -156,7 +158,7 @@ public class BlocksResource {
 		responses = {
 			@ApiResponse(
 				description = "the block",
-				//content = @Content(schema = @Schema(implementation = ???)),
+				content = @Content(schema = @Schema(implementation = BlockData.class)),
 				extensions = {
 					@Extension(name = "translation", properties = {
 						@ExtensionProperty(name="description.key", value="success_response:description")
@@ -191,10 +193,32 @@ public class BlocksResource {
 			)
 		}
 	)
-	public String getBlock(@PathParam("signature") String signature) {
+	public BlockData getBlock(@PathParam("signature") String signature) {
 		Security.checkApiCallAllowed("GET blocks", request);
 
-		throw new UnsupportedOperationException();
+		// decode signature
+		byte[] signatureBytes;
+		try
+		{
+			signatureBytes = Base58.decode(signature);
+		}
+		catch(Exception e)
+		{
+            throw this.apiErrorFactory.createError(ApiError.INVALID_SIGNATURE, e);
+		}
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().fromSignature(signatureBytes);
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return blockData;
+
+		} catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 
 	@GET
@@ -208,7 +232,7 @@ public class BlocksResource {
 		responses = {
 			@ApiResponse(
 				description = "the block",
-				//content = @Content(schema = @Schema(implementation = ???)),
+				content = @Content(schema = @Schema(implementation = BlockData.class)),
 				extensions = {
 					@Extension(name = "translation", properties = {
 						@ExtensionProperty(name="description.key", value="success_response:description")
@@ -217,10 +241,21 @@ public class BlocksResource {
 			)
 		}
 	)
-	public String getFirstBlock() {
+	public BlockData getFirstBlock() {
 		Security.checkApiCallAllowed("GET blocks/first", request);
 
-		throw new UnsupportedOperationException();
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().fromHeight(1);
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return blockData;
+
+		} catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 
 	@GET
@@ -234,7 +269,7 @@ public class BlocksResource {
 		responses = {
 			@ApiResponse(
 				description = "the block",
-				//content = @Content(schema = @Schema(implementation = ???)),
+				content = @Content(schema = @Schema(implementation = BlockData.class)),
 				extensions = {
 					@Extension(name = "translation", properties = {
 						@ExtensionProperty(name="description.key", value="success_response:description")
@@ -243,10 +278,21 @@ public class BlocksResource {
 			)
 		}
 	)
-	public String getLastBlock() {
+	public BlockData getLastBlock() {
 		Security.checkApiCallAllowed("GET blocks/last", request);
 
-		throw new UnsupportedOperationException();
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().getLastBlock();
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return blockData;
+
+		} catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 
 	@GET
@@ -295,10 +341,39 @@ public class BlocksResource {
 			)
 		}
 	)
-	public String getChild(@PathParam("signature") String signature) {
+	public BlockData getChild(@PathParam("signature") String signature) {
 		Security.checkApiCallAllowed("GET blocks/child", request);
 
-		throw new UnsupportedOperationException();
+		// decode signature
+		byte[] signatureBytes;
+		try
+		{
+			signatureBytes = Base58.decode(signature);
+		}
+		catch(Exception e)
+		{
+            throw this.apiErrorFactory.createError(ApiError.INVALID_SIGNATURE, e);
+		}
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().fromSignature(signatureBytes);
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			int height = blockData.getHeight();
+            BlockData childBlockData = repository.getBlockRepository().fromHeight(height + 1);
+
+			// check if child exists
+			if(childBlockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return childBlockData;
+			
+        } catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 
 	@GET
@@ -510,7 +585,29 @@ public class BlocksResource {
 	public int getHeight(@PathParam("signature") String signature) {
 		Security.checkApiCallAllowed("GET blocks/height", request);
 
-		throw new UnsupportedOperationException();
+		// decode signature
+		byte[] signatureBytes;
+		try
+		{
+			signatureBytes = Base58.decode(signature);
+		}
+		catch(Exception e)
+		{
+            throw this.apiErrorFactory.createError(ApiError.INVALID_SIGNATURE, e);
+		}
+
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().fromSignature(signatureBytes);
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return blockData.getHeight();
+			
+        } catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 
 	@GET
@@ -546,9 +643,20 @@ public class BlocksResource {
 			)
 		}
 	)
-	public String getbyHeight(@PathParam("height") int height) {
+	public BlockData getbyHeight(@PathParam("height") int height) {
 		Security.checkApiCallAllowed("GET blocks/byheight", request);
 
-		throw new UnsupportedOperationException();
+        try (final Repository repository = RepositoryManager.getRepository()) {
+            BlockData blockData = repository.getBlockRepository().fromHeight(height);
+				
+			// check if block exists
+			if(blockData == null)
+				throw this.apiErrorFactory.createError(ApiError.BLOCK_NO_EXISTS);
+
+			return blockData;
+			
+        } catch (Exception e) {
+            throw this.apiErrorFactory.createError(ApiError.UNKNOWN, e);
+        }
 	}
 }
diff --git a/src/data/block/BlockData.java b/src/data/block/BlockData.java
index 8c49b71b..ec98c594 100644
--- a/src/data/block/BlockData.java
+++ b/src/data/block/BlockData.java
@@ -3,8 +3,9 @@ package data.block;
 import java.math.BigDecimal;
 
 import com.google.common.primitives.Bytes;
+import java.io.Serializable;
 
-public class BlockData {
+public class BlockData implements Serializable {
 
 	private byte[] signature;
 	private int version;
@@ -20,6 +21,8 @@ public class BlockData {
 	private byte[] atBytes;
 	private BigDecimal atFees;
 
+	private BlockData() {} // necessary for JAX-RS serialization
+	
 	public BlockData(int version, byte[] reference, int transactionCount, BigDecimal totalFees, byte[] transactionsSignature, int height, long timestamp,
 			BigDecimal generatingBalance, byte[] generatorPublicKey, byte[] generatorSignature, byte[] atBytes, BigDecimal atFees) {
 		this.version = version;