diff --git a/server/gradle.properties b/server/gradle.properties
index ff0ed32..795c5e1 100644
--- a/server/gradle.properties
+++ b/server/gradle.properties
@@ -19,6 +19,7 @@ kotlin.code.style=official
 org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
 org.gradle.caching=true
 org.gradle.parallel=true
+org.gradle.configuration-cache=true
 
 # Application
 ccoin.version=1.0.0
diff --git a/server/src/main/kotlin/org/ccoin/models/Block.kt b/server/src/main/kotlin/org/ccoin/models/Block.kt
index a1b8966..9c2e53f 100644
--- a/server/src/main/kotlin/org/ccoin/models/Block.kt
+++ b/server/src/main/kotlin/org/ccoin/models/Block.kt
@@ -25,7 +25,7 @@ data class BlockResponse(
     val timestamp: Long,
     val difficulty: Int,
     val nonce: Long,
-    val minerAddress: String
+    val minerAddress: String,
     val reward: Double,
     val height: Int,
     val transactionCount: Int,
@@ -51,3 +51,11 @@ data class MiningStatsResponse(
     val lastBlockMined: Long?,
     val currentDifficulty: Int
 )
+
+@Serializable
+data class BlockRangeResponse(
+    val blocks: List<BlockResponse>,
+    val totalCount: Int,
+    val fromHeight: Int,
+    val toHeight: Int
+)
diff --git a/server/src/main/kotlin/org/ccoin/services/BlockService.kt b/server/src/main/kotlin/org/ccoin/services/BlockService.kt
index e69de29..26c8352 100644
--- a/server/src/main/kotlin/org/ccoin/services/BlockService.kt
+++ b/server/src/main/kotlin/org/ccoin/services/BlockService.kt
@@ -0,0 +1,218 @@
+package org.ccoin.services
+
+import org.ccoin.database.Tables
+import org.ccoin.models.BlockResponse
+import org.ccoin.models.BlockRangeResponse
+import org.jetbrains.exposed.sql.*
+import org.jetbrains.exposed.sql.transactions.transaction
+
+object BlockService {
+    /** Gets block by hash */
+    fun getBlock(hash: String): BlockResponse? = transaction {
+        Tables.Blocks.selectAll().where { Tables.Blocks.hash eq hash }
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }.singleOrNull()
+    }
+
+    /** Gets block by height */
+    fun getBlockByHeight(height: Int): BlockResponse? = transaction {
+        Tables.Blocks.selectAll().where { Tables.Blocks.height eq height }
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }.singleOrNull()    
+    }
+
+    /** Gets latest blocks */
+    fun getLatestBlocks(limit: Int = 10): List<BlockResponse> = transaction {
+        Tables.Blocks.selectAll()
+            .orderBy(Tables.Blocks.height, SortOrder.DESC)
+            .limit(limit)
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }
+    }
+
+    /** Gets blocks in height range */
+    fun getBlocksInRange(fromHeight: Int, toHeight: Int): BlockRangeResponse = transaction {
+        val blocks = Tables.Blocks.selectAll()
+            .where { Tables.Blocks.height.between(fromHeight, toHeight) }
+            .orderBy(Tables.Blocks.height, SortOrder.ASC)
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }
+        
+        BlockRangeResponse(blocks, blocks.size, fromHeight, toHeight)
+    }
+
+    /** Gets blocks mined by specific address */
+    fun getBlocksByMiner(minerAddress: String, limit: Int = 50, offset: Int = 0): List<BlockResponse> = transaction {
+        Tables.Blocks.selectAll()
+            .where { Tables.Blocks.minerAddress eq minerAddress }
+            .orderBy(Tables.Blocks.height, SortOrder.DESC)
+            .limit(limit)
+            .offset(offset.toLong())
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }
+    }
+
+    /** Gets total block count */
+    fun getTotalBlockCount(): Long = transaction {
+        Tables.Blocks.selectAll().count()
+    }
+    
+    /** Gets latest block height */
+    fun getLatestBlockHeight(): Int = transaction {
+        Tables.Blocks.selectAll()
+            .orderBy(Tables.Blocks.height, SortOrder.DESC)
+            .limit(1)
+            .map { it[Tables.Blocks.height] }
+            .singleOrNull() ?: 0
+    }
+    
+    /** Gets latest block hash */
+    fun getLatestBlockHash(): String = transaction {
+        Tables.Blocks.selectAll()
+            .orderBy(Tables.Blocks.height, SortOrder.DESC)
+            .limit(1)
+            .map { it[Tables.Blocks.hash] }
+            .singleOrNull() ?: "0".repeat(64)
+    }
+    
+    /** Checks if block exists */
+    fun blockExists(hash: String): Boolean = transaction {
+        Tables.Blocks.selectAll().where { Tables.Blocks.hash eq hash }.count() > 0
+    }
+    
+    /** Gets blocks by timestamp range */
+    fun getBlocksByTimeRange(fromTime: Long, toTime: Long): List<BlockResponse> = transaction {
+        Tables.Blocks.selectAll()
+            .where { Tables.Blocks.timestamp.between(fromTime, toTime) }
+            .orderBy(Tables.Blocks.timestamp, SortOrder.ASC)
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }
+    }
+    
+    /** Updates block confirmations */
+    fun updateBlockConfirmations(hash: String, confirmations: Int): Boolean = transaction {
+        val updated = Tables.Blocks.update({ Tables.Blocks.hash eq hash }) {
+            it[Tables.Blocks.confirmations] = confirmations
+        }
+        updated > 0
+    }
+    
+    /** Gets average block time over last N blocks */
+    fun getAverageBlockTime(blockCount: Int = 100): Long = transaction {
+        val blocks = Tables.Blocks.selectAll()
+            .orderBy(Tables.Blocks.timestamp, SortOrder.DESC)
+            .limit(blockCount)
+            .map { it[Tables.Blocks.timestamp] }
+        
+        if (blocks.size < 2) return@transaction 0L
+        
+        val timeDiffs = blocks.zipWithNext { newer, older -> newer - older }
+        timeDiffs.average().toLong()
+    }
+    
+    /** Gets total rewards distributed */
+    fun getTotalRewardsDistributed(): Double = transaction {
+        Tables.Blocks.select(Tables.Blocks.reward.sum())
+            .single()[Tables.Blocks.reward.sum()]?.toDouble() ?: 0.0
+    }
+    
+    /** Gets blocks with specific difficulty */
+    fun getBlocksByDifficulty(difficulty: Int): List<BlockResponse> = transaction {
+        Tables.Blocks.selectAll()
+            .where { Tables.Blocks.difficulty eq difficulty }
+            .orderBy(Tables.Blocks.height, SortOrder.DESC)
+            .map {
+                BlockResponse(
+                    it[Tables.Blocks.hash],
+                    it[Tables.Blocks.previousHash],
+                    it[Tables.Blocks.merkleRoot],
+                    it[Tables.Blocks.timestamp],
+                    it[Tables.Blocks.difficulty],
+                    it[Tables.Blocks.nonce],
+                    it[Tables.Blocks.minerAddress],
+                    it[Tables.Blocks.reward].toDouble(),
+                    it[Tables.Blocks.height],
+                    it[Tables.Blocks.transactionCount],
+                    it[Tables.Blocks.confirmations]
+                )
+            }
+    }
+}
diff --git a/server/src/main/kotlin/org/ccoin/services/ValidationService.kt b/server/src/main/kotlin/org/ccoin/services/ValidationService.kt
index e69de29..f6a2384 100644
--- a/server/src/main/kotlin/org/ccoin/services/ValidationService.kt
+++ b/server/src/main/kotlin/org/ccoin/services/ValidationService.kt
@@ -0,0 +1,200 @@
+package org.ccoin.services
+
+import org.ccoin.config.ServerConfig
+import org.ccoin.exceptions.InvalidTransactionException
+import org.ccoin.utils.CryptoUtils
+import org.ccoin.utils.HashUtils
+
+object ValidationService {
+    /** Validates wallet address format */
+    fun validateWalletAddress(address: String): Boolean = CryptoUtils.isValidAddress(address)
+
+    /** Validates transaction amount */
+    fun validateTransactionAmount(amount: Double): Boolean = amount > 0 && amount <= Double.MAX_VALUE && !amount.isNaN() && !amount.isInfinite()
+
+    /** Validates transaction fee */
+    fun validateTransactionFee(fee: Double): Boolean = fee >= 0 && fee <= Double.MAX_VALUE && !fee.isNaN() && !fee.isInfinite()
+
+    /** Validates memo length */
+    fun validateMemo(memo: String?): Boolean = memo == null || memo.length <= ServerConfig.maxMemoLength
+
+    /** Validates transaction hash format */
+    fun validateTransactionHash(hash: String): Boolean = HashUtils.isValidSha256Hash(hash)
+
+    /** Validates block hash format */
+    fun validateBlockHash(hash: String): Boolean = HashUtils.isValidSha256Hash(hash)
+
+    /** Validates mining difficulty */
+    fun validateMiningDifficulty(difficulty: Int): Boolean = difficulty in 1..32
+
+    /** Validates mining nonce */
+    fun validateMiningNonce(nonce: Long): Boolean = nonce >= 0
+
+    /** Validates timestamp */
+    fun validateTimestamp(timestamp: Long): Boolean {
+        val now = System.currentTimeMillis() / 1000
+        val oneHourAgo = now - 3600
+        val oneHourFromNow = now + 3600
+        return timestamp in oneHourAgo..oneHourFromNow
+    }
+
+    /** Validates wallet label */
+    fun validateWalletLabel(label: String?): Boolean = label == null || (label.isNotBlank() && label.length <= 255)
+
+    /** Validates page number for pagination */
+    fun validatePageNumber(page: Int): Boolean = page >= 1
+
+    /** Validates page size for pagination */
+    fun validatePageSize(pageSize: Int): Boolean = pageSize in 1..ServerConfig.maxPageSize
+
+    /** Validates mining hash meets difficulty requirement */
+    fun validateMiningHash(hash: String, difficulty: Int): Boolean = validateBlockHash(hash) && CryptoUtils.isValidHash(hash, difficulty)
+
+    /** Validates complete transaction data */
+    fun validateTransaction(
+        fromAddress: String?,
+        toAddress: String,
+        amount: Double,
+        fee: Double,
+        memo: String?
+    ): ValidationResult {
+        val errors = mutableListOf<String>()
+
+        // Validate addresses
+        if (fromAddress != null && !validateWalletAddress(fromAddress)) {
+            errors.add("Invalid from address format")
+        }
+
+        if (!validateWalletAddress(toAddress)) {
+            errors.add("Invalid to address format")
+        }
+
+        if (fromAddress == toAddress) {
+            errors.add("Cannot send to same address")
+        }
+
+        // Validate amounts
+        if (!validateTransactionAmount(amount)) {
+            errors.add("Invalid transaction amount")
+        }
+
+        if (!validateTransactionFee(fee)) {
+            errors.add("Invalid transaction fee")
+        }
+
+        // Validate memo
+        if (!validateMemo(memo)) {
+            errors.add("Memo too long (max ${ServerConfig.maxMemoLength} characters)")
+        }
+
+        return ValidationResult(errors.isEmpty(), errors)
+    }
+
+    /** Validates complete block data */
+    fun validateBlock(
+        hash: String,
+        previousHash: String?,
+        merkleRoot: String,
+        timestamp: Long,
+        difficulty: Int,
+        nonce: Long,
+        minerAddress: String
+    ): ValidationResult {
+        val errors = mutableListOf<String>()
+
+        // Validate hash
+        if (!validateBlockHash(hash)) {
+            errors.add("Invalid block hash format")
+        }
+
+        // Validate previous hash
+        if (previousHash != null && !validateBlockHash(previousHash)) {
+            errors.add("Invalid previous hash format")
+        }
+
+        // Validate merkle root
+        if (!validateBlockHash(merkleRoot)) {
+            errors.add("Invalid merkle root format")
+        }
+
+        // Validate timestamp
+        if (!validateTimestamp(timestamp)) {
+            errors.add("Invalid timestamp (must be within 1 hour of current time)")
+        }
+
+        // Validate difficulty
+        if (!validateMiningDifficulty(difficulty)) {
+            errors.add("Invalid mining difficulty (must be between 1 and 32)")
+        }
+
+        // Validate nonce
+        if (!validateMiningNonce(nonce)) {
+            errors.add("Invalid nonce (must be non-negative)")
+        }
+
+        // Validate miner address
+        if (!validateWalletAddress(minerAddress)) {
+            errors.add("Invalid miner address format")
+        }
+
+        // Validate hash meets difficulty
+        if (!validateMiningHash(hash, difficulty)) {
+            errors.add("Hash does not meet difficulty requirements")
+        }
+
+        return ValidationResult(errors.isEmpty(), errors)
+    }
+
+    /** Validates wallet creation data */
+    fun validateWalletCreation(label: String?): ValidationResult {
+        val errors = mutableListOf<String>()
+
+        if (!validateWalletLabel(label)) {
+            errors.add("Invalid wallet label")
+        }
+
+        return ValidationResult(errors.isEmpty(), errors)
+    }
+
+    /** Validates pagination parameters */
+    fun validatePagination(page: Int, pageSize: Int): ValidationResult {
+        val errors = mutableListOf<String>()
+
+        if (!validatePageNumber(page)) {
+            errors.add("Page number must be >= 1")
+        }
+
+        if (!validatePageSize(pageSize)) {
+            errors.add("Page size must be between 1 and ${ServerConfig.maxPageSize}")
+        }
+
+        return ValidationResult(errors.isEmpty(), errors)
+    }
+
+    /** Sanitizes user input */
+    fun sanitizeInput(input: String): String {
+        return input.trim()
+        .replace(Regex("[\\r\\n\\t]"), " ")
+        .replace(Regex("\\s+"), " ")
+    }
+
+    /** Validates hex string */
+    fun validateHexString(hex: String, expectedLength: Int? = null): Boolean {
+        if (!HashUtils.isValidHex(hex)) return false
+        return expectedLength == null || hex.length == expectedLength
+    }
+}
+
+/** Result of validation with success status and error messages */
+data class ValidationResult(
+    val isValid: Boolean,
+    val errors: List<String> = emptyList()
+) {
+    fun getErrorMessage(): String = errors.joinToString(", ")
+
+    fun throwIfInvalid() {
+        if (!isValid) {
+            throw InvalidTransactionException(getErrorMessage())
+        }
+    }
+}