diff --git a/block.go b/blockchain/block.go
similarity index 95%
rename from block.go
rename to blockchain/block.go
index bf99487b1..8727ce8db 100644
--- a/block.go
+++ b/blockchain/block.go
@@ -1,4 +1,4 @@
-package main
+package blockchain
 
 import (
 	"bytes"
@@ -44,7 +44,7 @@ func (b *Block) HashTransactions() []byte {
 	var txHash [32]byte
 
 	for _, tx := range b.Transactions {
-		txHashes = append(txHashes, tx.ID)
+		txHashes = append(txHashes, tx.id)
 	}
 	txHash = sha256.Sum256(bytes.Join(txHashes, []byte{}))
 	return txHash[:]
@@ -52,7 +52,7 @@ func (b *Block) HashTransactions() []byte {
 
 // NewBlock creates and returns Block.
 func NewBlock(transactions []*Transaction, prevBlockHash []byte) *Block {
-	block := &Block{time.Now().Unix(), transactions, prevBlockHash, []byte{}, 0}
+	block := &Block{time.Now().Unix(), transactions, prevBlockHash, []byte{}}
 	block.Hash = block.HashTransactions()
 	return block
 }
diff --git a/blockchain/block_test.go b/blockchain/block_test.go
new file mode 100644
index 000000000..194471681
--- /dev/null
+++ b/blockchain/block_test.go
@@ -0,0 +1,26 @@
+package blockchain
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestBlockSerialize(t *testing.T) {
+	cbtx := NewCoinbaseTX("minh", genesisCoinbaseData)
+	block := NewGenesisBlock(cbtx)
+
+	serializedValue := block.Serialize()
+	deserializedBlock := DeserializeBlock(serializedValue)
+
+	if block.Timestamp != deserializedBlock.Timestamp {
+		t.Errorf("Serialize or Deserialize incorrect at TimeStamp.")
+	}
+
+	if bytes.Compare(block.PrevBlockHash, deserializedBlock.PrevBlockHash) != 0 {
+		t.Errorf("Serialize or Deserialize incorrect at PrevBlockHash.")
+	}
+
+	if bytes.Compare(block.Hash, deserializedBlock.Hash) != 0 {
+		t.Errorf("Serialize or Deserialize incorrect at Hash.")
+	}
+}
diff --git a/blockchain.go b/blockchain/blockchain.go
similarity index 87%
rename from blockchain.go
rename to blockchain/blockchain.go
index 7365bc6d0..aee40b1f0 100644
--- a/blockchain.go
+++ b/blockchain/blockchain.go
@@ -1,4 +1,4 @@
-package main
+package blockchain
 
 import (
 	"encoding/hex"
@@ -11,11 +11,6 @@ type Blockchain struct {
 
 const genesisCoinbaseData = "The Times 03/Jan/2009 Chancellor on brink of second bailout for banks"
 
-// NewBlockchain creates a new Blockchain with genesis Block
-func NewBlockchain(address string) *Blockchain {
-	return &Blockchain{[]*Block{NewGenesisBlock()}}
-}
-
 // FindUnspentTransactions returns a list of transactions containing unspent outputs
 func (bc *Blockchain) FindUnspentTransactions(address string) []Transaction {
 	var unspentTXs []Transaction
@@ -26,14 +21,14 @@ func (bc *Blockchain) FindUnspentTransactions(address string) []Transaction {
 
 	BreakTransaction:
 		for _, tx := range block.Transactions {
-			txId := hex.EncodeToString(tx.Id)
+			txID := hex.EncodeToString(tx.id)
 
 			idx := -1
-			if spentTXOs[txId] != nil {
+			if spentTXOs[txID] != nil {
 				idx = 0
 			}
 			for outIdx, txOutput := range tx.txOutput {
-				if idx >= 0 && spentTXOs[txId][idx] == outIdx {
+				if idx >= 0 && spentTXOs[txID][idx] == outIdx {
 					idx++
 					continue
 				}
@@ -73,7 +68,7 @@ func (bc *Blockchain) FindSpendableOutputs(address string, amount int) (int, map
 
 Work:
 	for _, tx := range unspentTXs {
-		txID := hex.EncodeToString(tx.ID)
+		txID := hex.EncodeToString(tx.id)
 
 		for outIdx, txOutput := range tx.txOutput {
 			if txOutput.address == address && accumulated < amount {
diff --git a/transaction.go b/blockchain/transaction.go
similarity index 99%
rename from transaction.go
rename to blockchain/transaction.go
index 51480aad3..5f2495efa 100644
--- a/transaction.go
+++ b/blockchain/transaction.go
@@ -1,4 +1,4 @@
-package main
+package blockchain
 
 import (
 	"bytes"
diff --git a/blockchain/transaction_test.go b/blockchain/transaction_test.go
new file mode 100644
index 000000000..4f4054e5c
--- /dev/null
+++ b/blockchain/transaction_test.go
@@ -0,0 +1,9 @@
+package blockchain
+
+import (
+	"testing"
+)
+
+func TestNewCoinbaseTX(t *testing.T) {
+	NewCoinbaseTX("minh", genesisCoinbaseData)
+}
diff --git a/utils.go b/utils/utils.go
similarity index 72%
rename from utils.go
rename to utils/utils.go
index d3cb517b0..4011e1a23 100644
--- a/utils.go
+++ b/utils/utils.go
@@ -1,4 +1,4 @@
-package main
+package utils
 
 import (
 	"bytes"
@@ -19,14 +19,15 @@ func IntToHex(num int64) []byte {
 	return buff.Bytes()
 }
 
-// Helper library to convert '1,2,3,4' into []int{1,2,3,4}.
+// ConvertIntoInts is to convert '1,2,3,4' into []int{1,2,3,4}.
 func ConvertIntoInts(data string) []int {
 	var res = []int{}
-	items := strings.Split(data, " ")
+	items := strings.Split(data, ",")
 	for _, value := range items {
 		intValue, err := strconv.Atoi(value)
-		checkError(err)
-		res = append(res, intValue)
+		if err == nil {
+			res = append(res, intValue)
+		}
 	}
 	return res
 }
diff --git a/utils/utils_test.go b/utils/utils_test.go
new file mode 100644
index 000000000..366936d36
--- /dev/null
+++ b/utils/utils_test.go
@@ -0,0 +1,17 @@
+package utils
+
+import "testing"
+
+func TestConvertIntoInts(t *testing.T) {
+	data := "1,2,3,4"
+	res := ConvertIntoInts(data)
+	if len(res) != 4 {
+		t.Errorf("Array length parsed incorrect.")
+	}
+
+	for id, value := range res {
+		if value != id+1 {
+			t.Errorf("Parsing incorrect.")
+		}
+	}
+}
diff --git a/utils_test.go b/utils_test.go
deleted file mode 100644
index bc7255297..000000000
--- a/utils_test.go
+++ /dev/null
@@ -1,25 +0,0 @@
-package main
-
-import "testing"
-
-func TestConvertIntoMap(t *testing.T) {
-	data := "minh:3,mike:2"
-	res := ConvertIntoMap(data)
-	if len(res) != 2 {
-		t.Errorf("Result should have 2 pairs (key, value)")
-	}
-	if val, ok := res["minh"]; !ok {
-		t.Errorf("Result should contain key minh")
-	} else {
-		if res["minh"] != 3 {
-			t.Errorf("Value of minh should be 3")
-		}
-	}
-	if val, ok := res["mike"]; !ok {
-		t.Errorf("Result should contain key mike")
-	} else {
-		if res["minh"] != 3 {
-			t.Errorf("Value of minh should be 2")
-		}
-	}
-}