diff --git a/README.md b/README.md
index 69fbef5..098e85e 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 [![Build Status](https://travis-ci.org/sc0Vu/web3.php.svg?branch=master)](https://travis-ci.org/sc0Vu/web3.php)
 [![codecov](https://codecov.io/gh/sc0Vu/web3.php/branch/master/graph/badge.svg)](https://codecov.io/gh/sc0Vu/web3.php)
 [![Join the chat at https://gitter.im/web3-php/web3.php](https://img.shields.io/badge/gitter-join%20chat-brightgreen.svg)](https://gitter.im/web3-php/web3.php)
+[![Licensed under the MIT License](https://img.shields.io/badge/License-MIT-blue.svg)](https://github.com/sc0Vu/web3.php/blob/master/LICENSE)
+
 
 A php interface for interacting with the Ethereum blockchain and ecosystem.
 
@@ -173,7 +175,7 @@ $contract->at($contractAddress)->send($functionName, $params, $callback);
 $contract->bytecode($bytecode)->estimateGas($params, $callback);
 
 // estimate function gas
-$contract->bytecode($bytecode)->estimateGas($functionName, $params, $callback);
+$contract->at($contractAddress)->estimateGas($functionName, $params, $callback);
 ```
 
 # Assign value to outside scope(from callback scope to outside scope)
diff --git a/src/Contracts/Ethabi.php b/src/Contracts/Ethabi.php
index c826d7d..e2d1f5f 100644
--- a/src/Contracts/Ethabi.php
+++ b/src/Contracts/Ethabi.php
@@ -153,7 +153,7 @@ class Ethabi
             throw new InvalidArgumentException('encodeParameters number of types must equal to number of params.');
         }
         $typesLength = count($types);
-        $solidityTypes = array_fill(0, $typesLength, 0);
+        $solidityTypes = $this->getSolidityTypes($types);
 
         foreach ($types as $key => $type) {
             $match = [];
@@ -189,6 +189,101 @@ class Ethabi
         return '0x' . $this->encodeMultiWithOffset($types, $solidityTypes, $encodes, $dynamicOffset);
     }
 
+    /**
+     * decodeParameter
+     * 
+     * @param string $type
+     * @param mixed $param
+     * @return string
+     */
+    public function decodeParameter($type, $param)
+    {
+        if (!is_string($type)) {
+            throw new InvalidArgumentException('The type to decodeParameter must be string.');
+        }
+        return $this->decodeParameters([$type], $param)[0];
+    }
+
+    /**
+     * decodeParameters
+     * 
+     * @param stdClass|array $type
+     * @param string $param
+     * @return string
+     */
+    public function decodeParameters($types, $param)
+    {
+        if (!is_string($param)) {
+            throw new InvalidArgumentException('The type or param to decodeParameters must be string.');
+        }
+
+        // change json to array
+        if ($types instanceof stdClass && isset($types->outputs)) {
+            $types = Utils::jsonToArray($types, 2);
+        }
+        if (is_array($types) && isset($types['outputs'])) {
+            $outputTypes = $types;
+            $types = [];
+
+            foreach ($outputTypes['outputs'] as $output) {
+                if (isset($output['type'])) {
+                    $types[] = $output['type'];
+                }
+            }
+        }
+        $typesLength = count($types);
+        $solidityTypes = $this->getSolidityTypes($types);
+        $offsets = array_fill(0, $typesLength, 0);
+
+        for ($i=0; $i<$typesLength; $i++) {
+            $offsets[$i] = $solidityTypes[$i]->staticPartLength($types[$i]);
+        }
+        for ($i=1; $i<$typesLength; $i++) {
+            $offsets[$i] += $offsets[$i - 1];
+        }
+        for ($i=0; $i<$typesLength; $i++) {
+            $offsets[$i] -= $solidityTypes[$i]->staticPartLength($types[$i]);
+        }
+        $result = [];
+        $param = mb_strtolower(Utils::stripZero($param));
+
+        for ($i=0; $i<$typesLength; $i++) {
+            $result[$i] = $solidityTypes[$i]->decode($param, $offsets[$i], $types[$i]);
+        }
+
+        return $result;
+    }
+
+    /**
+     * getSolidityTypes
+     * 
+     * @param array $types
+     * @return array
+     */
+    protected function getSolidityTypes($types)
+    {
+        if (!is_array($types)) {
+            throw new InvalidArgumentException('Types must be array');
+        }
+        $solidityTypes = array_fill(0, count($types), 0);
+
+        foreach ($types as $key => $type) {
+            $match = [];
+
+            if (preg_match('/^([a-zA-Z]+)/', $type, $match) === 1) {
+                if (isset($this->types[$match[0]])) {
+                    $className = $this->types[$match[0]];
+
+                    if (call_user_func([$this->types[$match[0]], 'isType'], $type) === false) {
+                        throw new InvalidArgumentException('Unsupport solidity parameter type: ' . $type);
+                    }
+                    $solidityTypes[$key] = $className;
+                }
+            }
+        }
+        return $solidityTypes;
+    }
+
     /**
      * encodeWithOffset
      * 
diff --git a/src/Contracts/SolidityType.php b/src/Contracts/SolidityType.php
index 11c7c5c..98474ac 100644
--- a/src/Contracts/SolidityType.php
+++ b/src/Contracts/SolidityType.php
@@ -184,6 +184,16 @@ class SolidityType
         return $count;
     }
 
+    /**
+     * isDynamicType
+     * 
+     * @return bool
+     */
+    public function isDynamicType()
+    {
+        return false;
+    }
+
     /**
      * encode
      * 
@@ -215,4 +225,54 @@ class SolidityType
         }
         return $this->inputFormat($value, $name);
     }
+
+    /**
+     * decode
+     * 
+     * @param mixed $value
+     * @param string $offset
+     * @param string $name
+     * @return array
+     */
+    public function decode($value, $offset, $name)
+    {
+        if ($this->isDynamicArray($name)) {
+            $arrayOffset = (int) Utils::toBn('0x' . mb_substr($value, $offset * 2, 64))->toString();
+            $length = (int) Utils::toBn('0x' . mb_substr($value, $arrayOffset * 2, 64))->toString();
+            $arrayStart = $arrayOffset + 32;
+
+            $nestedName = $this->nestedName($name);
+            $nestedStaticPartLength = $this->staticPartLength($nestedName);
+            $roundedNestedStaticPartLength = floor(($nestedStaticPartLength + 31) / 32) * 32;
+            $result = [];
+
+            for ($i=0; $i<$length * $roundedNestedStaticPartLength; $i+=$roundedNestedStaticPartLength) {
+                $result[] = $this->decode($value, $arrayStart + $i, $nestedName);
+            }
+            return $result;
+        } elseif ($this->isStaticArray($name)) {
+            $length = $this->staticArrayLength($name);
+            $arrayStart = $offset;
+
+            $nestedName = $this->nestedName($name);
+            $nestedStaticPartLength = $this->staticPartLength($nestedName);
+            $roundedNestedStaticPartLength = floor(($nestedStaticPartLength + 31) / 32) * 32;
+            $result = [];
+
+            for ($i=0; $i<$length * $roundedNestedStaticPartLength; $i+=$roundedNestedStaticPartLength) {
+                $result[] = $this->decode($value, $arrayStart + $i, $nestedName);
+            }
+            return $result;
+        } elseif ($this->isDynamicType()) {
+            $dynamicOffset = (int) Utils::toBn('0x' . mb_substr($value, $offset * 2, 64))->toString();
+            $length = (int) Utils::toBn('0x' . mb_substr($value, $dynamicOffset * 2, 64))->toString();
+            $roundedLength = floor(($length + 31) / 32);
+            $param = mb_substr($value, $dynamicOffset * 2, ( 1 + $roundedLength) * 64);
+            return $this->outputFormat($param, $name);
+        }
+        $length = $this->staticPartLength($name);
+        $param = mb_substr($value, $offset * 2, $length * 2);
+
+        return $this->outputFormat($param, $name);
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Address.php b/src/Contracts/Types/Address.php
index f93e882..011679a 100644
--- a/src/Contracts/Types/Address.php
+++ b/src/Contracts/Types/Address.php
@@ -73,4 +73,16 @@ class Address extends SolidityType implements IType
 
         return $value;
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        return '0x' . mb_substr($value, 24, 40);
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Boolean.php b/src/Contracts/Types/Boolean.php
index 6ec38c7..3850761 100644
--- a/src/Contracts/Types/Boolean.php
+++ b/src/Contracts/Types/Boolean.php
@@ -64,4 +64,18 @@ class Boolean extends SolidityType implements IType
 
         return '000000000000000000000000000000000000000000000000000000000000000' . $value;
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $value = (int) mb_substr($value, 63, 1);
+
+        return (bool) $value;
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Bytes.php b/src/Contracts/Types/Bytes.php
index eba8a9c..55b13fc 100644
--- a/src/Contracts/Types/Bytes.php
+++ b/src/Contracts/Types/Bytes.php
@@ -75,4 +75,21 @@ class Bytes extends SolidityType implements IType
 
         return $value . implode('', array_fill(0, $padding, '0'));
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $checkZero = str_replace('0', '', $value);
+
+        if (empty($checkZero)) {
+            return '0';
+        }
+        return '0x' . $value;
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/DynamicBytes.php b/src/Contracts/Types/DynamicBytes.php
index d95d50f..a0c8842 100644
--- a/src/Contracts/Types/DynamicBytes.php
+++ b/src/Contracts/Types/DynamicBytes.php
@@ -74,4 +74,21 @@ class DynamicBytes extends SolidityType implements IType
 
         return implode('', array_fill(0, 64-mb_strlen($bnHex), $padded)) . $bnHex . $value . implode('', array_fill(0, $padding, '0'));
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $checkZero = str_replace('0', '', $value);
+
+        if (empty($checkZero)) {
+            return '0';
+        }
+        return '0x' . $value;
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Integer.php b/src/Contracts/Types/Integer.php
index ca0e557..d2078a3 100644
--- a/src/Contracts/Types/Integer.php
+++ b/src/Contracts/Types/Integer.php
@@ -15,6 +15,7 @@ use Web3\Utils;
 use Web3\Contracts\SolidityType;
 use Web3\Contracts\Types\IType;
 use Web3\Formatters\Integer as IntegerFormatter;
+use Web3\Formatters\BigNumberFormatter;
 
 class Integer extends SolidityType implements IType
 {
@@ -60,4 +61,22 @@ class Integer extends SolidityType implements IType
     {
         return IntegerFormatter::format($value);
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $match = [];
+
+        if (preg_match('/^[0]+([a-f0-9]+)$/', $value, $match) === 1) {
+            // due to value without 0x prefix, we will parse as decimal
+            $value = '0x' . $match[1];
+        }
+        return BigNumberFormatter::format($value);
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Str.php b/src/Contracts/Types/Str.php
index 5691c6d..7a8a227 100644
--- a/src/Contracts/Types/Str.php
+++ b/src/Contracts/Types/Str.php
@@ -15,6 +15,7 @@ use Web3\Utils;
 use Web3\Contracts\SolidityType;
 use Web3\Contracts\Types\IType;
 use Web3\Formatters\Integer as IntegerFormatter;
+use Web3\Formatters\BigNumberFormatter;
 
 class Str extends SolidityType implements IType
 {
@@ -65,4 +66,25 @@ class Str extends SolidityType implements IType
 
         return $prefix . $value . implode('', array_fill(0, $padding, '0'));
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $strLen = mb_substr($value, 0, 64);
+        $strValue = mb_substr($value, 64, 64);
+        $match = [];
+
+        if (preg_match('/^[0]+([a-f0-9]+)$/', $strLen, $match) === 1) {
+            $strLen = BigNumberFormatter::format('0x' . $match[1])->toString();
+        }
+        $strValue = mb_substr($strValue, 0, (int) $strLen * 2);
+
+        return Utils::hexToBin($strValue);
+    }
 }
\ No newline at end of file
diff --git a/src/Contracts/Types/Uinteger.php b/src/Contracts/Types/Uinteger.php
index b294666..d5dd4b2 100644
--- a/src/Contracts/Types/Uinteger.php
+++ b/src/Contracts/Types/Uinteger.php
@@ -15,6 +15,7 @@ use Web3\Utils;
 use Web3\Contracts\SolidityType;
 use Web3\Contracts\Types\IType;
 use Web3\Formatters\Integer as IntegerFormatter;
+use Web3\Formatters\BigNumberFormatter;
 
 class Uinteger extends SolidityType implements IType
 {
@@ -60,4 +61,22 @@ class Uinteger extends SolidityType implements IType
     {
         return IntegerFormatter::format($value);
     }
+
+    /**
+     * outputFormat
+     * 
+     * @param mixed $value
+     * @param string $name
+     * @return string
+     */
+    public function outputFormat($value, $name)
+    {
+        $match = [];
+
+        if (preg_match('/^[0]+([a-f0-9]+)$/', $value, $match) === 1) {
+            // due to value without 0x prefix, we will parse as decimal
+            $value = '0x' . $match[1];
+        }
+        return BigNumberFormatter::format($value);
+    }
 }
\ No newline at end of file
diff --git a/test/unit/EthabiTest.php b/test/unit/EthabiTest.php
index d056f6b..2d900ce 100644
--- a/test/unit/EthabiTest.php
+++ b/test/unit/EthabiTest.php
@@ -56,13 +56,14 @@ class EthabiTest extends TestCase
     }';
 
     /**
-     * tests
-     * from web3 eth.abi.encodeParameters test
+     * encodingTests
+     * from web3 abi.encodeParameter.js test
+     * and web3 eth.abi.encodeParameters test
      * and web3 eth.abi.encodeParameter test
      * 
      * @param array
      */
-    protected $tests = [
+    protected $encodingTests = [
         [
             'params' => [['uint256','string'], ['2345675643', 'Hello!%']],
             'result' => '0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000'
@@ -108,6 +109,54 @@ class EthabiTest extends TestCase
         ]
     ];
 
+    /**
+     * decodingTests
+     * from web3 abi.decodeParameter.js test
+     * and web3 eth.abi.decodeParameters test
+     * and web3 eth.abi.decodeParameter test
+     * 
+     * @param array
+     */
+    protected $decodingTests = [
+        [
+            'params' => [['uint256'], '0x0000000000000000000000000000000000000000000000000000000000000010'],
+            'result' => ['16']
+        ], [
+            'params' => [['string'], '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000'],
+            'result' => ['Hello!%!']
+        ], [
+            'params' => [['uint256','string'], '0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000'],
+            'result' => ['2345675643', 'Hello!%']
+        ], [
+            'params' => [['string'], '0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['']
+        ], [
+            'params' => [['int256'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0']
+        ], [
+            'params' => [['uint256'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0']
+        ], [
+            'params' => [['address'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0x0000000000000000000000000000000000000000']
+        ], [
+            'params' => [['bool'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => [false]
+        ], [
+            'params' => [['bytes'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0']
+        ], [
+            'params' => [['bytes32'], '0x0000000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0']
+        ], [
+            'params' => [['bytes32'], '0xdf32340000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0xdf32340000000000000000000000000000000000000000000000000000000000']
+        ], [
+            'params' => [['bytes32[]'], '0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002df32340000000000000000000000000000000000000000000000000000000000fdfd000000000000000000000000000000000000000000000000000000000000'],
+            'result' => ['0xdf32340000000000000000000000000000000000000000000000000000000000', '0xfdfd000000000000000000000000000000000000000000000000000000000000']
+        ]
+    ];
+
     /**
      * setUp
      * 
@@ -182,6 +231,18 @@ class EthabiTest extends TestCase
         $this->assertEquals($str, '0x095ea7b334ae44009aa867bfb386f5c3b4b443ac6f0ee573fa91c4608fbadfba');
     }
 
+    /**
+     * testEncodeParameter
+     * 
+     * @return void
+     */
+    public function testEncodeParameter()
+    {
+        $abi = $this->abi;
+
+        $this->assertEquals('0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff', $abi->encodeParameter('int256', '-1'));
+    }
+
     /**
      * testEncodeParameters
      * 
@@ -191,8 +252,45 @@ class EthabiTest extends TestCase
     {
         $abi = $this->abi;
 
-        foreach ($this->tests as $test) {
+        foreach ($this->encodingTests as $test) {
             $this->assertEquals($test['result'], $abi->encodeParameters($test['params'][0], $test['params'][1]));
         }
     }
+
+    /**
+     * testDecodeParameter
+     * 
+     * @return void
+     */
+    public function testDecodeParameter()
+    {
+        $abi = $this->abi;
+
+        $this->assertEquals('16', $abi->decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010')->toString());
+        $this->assertEquals('16', $abi->decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010')->toString());
+    }
+
+    /**
+     * testDecodeParameters
+     * 
+     * @return void
+     */
+    public function testDecodeParameters()
+    {
+        $abi = $this->abi;
+
+        foreach ($this->decodingTests as $test) {
+            $decoded = $abi->decodeParameters($test['params'][0], $test['params'][1]);
+
+            foreach ($decoded as $key => $decoding) {
+                if (!is_array($decoding)) {
+                    $this->assertEquals($test['result'][$key], $decoding);
+                } else {
+                    foreach ($test['result'] as $rKey => $expected) {
+                        $this->assertEquals($expected, $decoding[$rKey]);
+                    }
+                }
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/test/unit/SolidityTypeTest.php b/test/unit/SolidityTypeTest.php
index 2cc5aab..941deb2 100644
--- a/test/unit/SolidityTypeTest.php
+++ b/test/unit/SolidityTypeTest.php
@@ -123,9 +123,20 @@ class SolidityTypeTest extends TestCase
      * 
      * @return void
      */
-    public function testEncode()
-    {
-        $type = $this->type;
-        $this->assertTrue(true);
-    }
+    // public function testEncode()
+    // {
+    //     $type = $this->type;
+    //     $this->assertTrue(true);
+    // }
+
+    /**
+     * testDecode
+     * 
+     * @return void
+     */
+    // public function testDecode()
+    // {
+    //     $type = $this->type;
+    //     $this->assertTrue(true);
+    // }
 }
\ No newline at end of file