diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 41cef6c..7e0764d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-version: ['5.3', '5.4', '5.5', '5.6', '7.0', '7.1', '7.2', '7.3', '7.4']
+        php-version: ['8.0', '8.1', '8.2', '8.3', '8.4']
     steps:
     - name: Checkout
       uses: actions/checkout@v2
@@ -23,7 +23,7 @@ jobs:
     - name: Run Tests
       run: vendor/bin/phpunit --coverage-clover ./coverage.xml
     - name: Upload Coverage
-      if: ${{ matrix.php-version == '7.4' }}
+      if: ${{ matrix.php-version == '8.2' }}
       uses: codecov/codecov-action@v1
       with:
         file: ./coverage.xml
diff --git a/LICENSE b/LICENSE
index f9f0c99..ab5ad02 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2016, 2017, 2018, 2019, 2020 Gravity Boulevard, LLC
+Copyright (c) 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023 Gravity Boulevard, LLC
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/README.md b/README.md
index f587bf7..81a1456 100644
--- a/README.md
+++ b/README.md
@@ -2,25 +2,11 @@
 
 [![License](https://img.shields.io/packagist/l/holidayapi/holidayapi-php?style=for-the-badge)](https://github.com/holidayapi/holidayapi-php/blob/master/LICENSE)
 ![PHP Version](https://img.shields.io/packagist/php-v/holidayapi/holidayapi-php?style=for-the-badge)
-[![Test Status](https://img.shields.io/github/workflow/status/joshtronic/holidayapi-php/Test?style=for-the-badge)](https://github.com/joshtronic/holidayapi-php/actions)
-[![Code Coverage](https://img.shields.io/codecov/c/github/joshtronic/holidayapi-php?style=for-the-badge)](https://codecov.io/gh/joshtronic/holidayapi-php)
+[![Code Coverage](https://img.shields.io/codecov/c/github/holidayapi/holidayapi-php?style=for-the-badge)](https://codecov.io/gh/holidayapi/holidayapi-php)
 
 Official PHP library for [Holiday API](https://holidayapi.com) providing quick
 and easy access to holiday information from applications written in PHP.
 
-## Migrating from 1.x
-
-Please note, version 2.x of this library is a full rewrite of the 1.x series.
-The interfacing to the library has been simplified and existing applications
-upgrading to 2.x will need to be updated.
-
-| Version 1.x Syntax (Old)                   | Version 2.x Syntax (New)                                  |
-|--------------------------------------------|-----------------------------------------------------------|
-| `$holiday_api = new \HolidayAPI\v1($key);` | `$holiday_api = new \HolidayAPI\Client(['key' => $key]);` |
-
-Version 1.x of the library can still be found
-[here](https://github.com/joshtronic/php-holidayapi).
-
 ## Documentation
 
 Full documentation of the Holiday API endpoints is available
@@ -252,3 +238,29 @@ $holiday_api->holidays([
   'year' => 2019,
 ]);
 ```
+
+### Workday
+
+#### Fetch workday 7 business days after a date
+
+```php
+<?php
+$holiday_api->workday([
+  'country' => 'US',
+  'start' => '2019-07-01',
+  'days' => 7,
+]);
+```
+
+### Workdays
+
+#### Fetch number of workdays between two dates
+
+```php
+<?php
+$holiday_api->workdays([
+  'country' => 'US',
+  'start' => '2019-07-01',
+  'end' => '2019-07-10',
+]);
+```
diff --git a/composer.json b/composer.json
index c1c0886..3129ca8 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
   "name": "holidayapi/holidayapi-php",
   "description": "Official PHP library for Holiday API",
-  "version": "2.2.2",
+  "version": "4.0.0",
   "type": "library",
   "keywords": [
     "calendar",
@@ -17,14 +17,21 @@
     "homepage": "https://holidayapi.com"
   }],
   "require": {
-    "php": ">=5.3"
+    "php": ">=8.0",
+    "ext-json": "*",
+    "ext-curl": "*"
   },
   "require-dev": {
-    "phpunit/phpunit": ">=4"
+    "phpunit/phpunit": "^9.0"
   },
   "autoload": {
     "psr-4": {
       "HolidayAPI\\": "src/"
     }
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "HolidayAPI\\Tests\\": "tests/"
+    }
   }
 }
diff --git a/phpunit.xml b/phpunit.xml
index fa05f6b..92f2230 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
   colors="true"
+  bootstrap="./vendor/autoload.php"
   convertErrorsToExceptions="true"
   convertNoticesToExceptions="true"
   convertWarningsToExceptions="true"
diff --git a/src/Client.php b/src/Client.php
index c482865..0793c97 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -64,17 +64,6 @@ class Client
 
     public function holidays($request)
     {
-        if (!isset($request['country'])) {
-            throw new \Exception('Missing country');
-        } elseif (!isset($request['year'])) {
-            throw new \Exception('Missing year');
-        } elseif (
-            isset($request['previous'], $request['upcoming'])
-            && $request['previous'] && $request['upcoming']
-        ) {
-            throw new \Exception('Previous and upcoming are mutually exclusive');
-        }
-
         return $this->request('holidays', $request);
     }
 
@@ -82,5 +71,15 @@ class Client
     {
         return $this->request('languages', $request);
     }
+
+    public function workday($request)
+    {
+        return $this->request('workday', $request);
+    }
+
+    public function workdays($request)
+    {
+        return $this->request('workdays', $request);
+    }
 }
 
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 30a96b3..14f83c7 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -2,56 +2,72 @@
 namespace HolidayAPI\Tests;
 use HolidayAPI\Client;
 use HolidayAPI\Request;
+use PHPUnit\Framework\TestCase;
 
-require __DIR__ . '/../vendor/autoload.php';
-
-if (
-    !class_exists('\PHPUnit_Framework_TestCase')
-    && class_exists('\PHPUnit\Framework\TestCase')
-) {
-    class_alias('\PHPUnit\Framework\TestCase', '\PHPUnit_Framework_TestCase');
-}
-
-class ClientTest extends \PHPUnit_Framework_TestCase
+class ClientTest extends TestCase
 {
     const BASE_URL = 'https://holidayapi.com/v1/';
     const KEY = '8e4de28c-4b18-49f0-9aba-0bd6b424fc38';
 
     public function testMissingKey()
     {
+        if (version_compare(PHP_VERSION, '7.3.0', '>=')) {
+            $assertRegExp = 'assertMatchesRegularExpression';
+        } else {
+            $assertRegExp = 'assertRegExp';
+        }
+
         try {
-            $client = new Client(array());
+            new Client(array());
         } catch (\Exception $e) {
-            $this->assertRegExp('/missing api key/i', $e->getMessage());
+            $this->$assertRegExp('/missing api key/i', $e->getMessage());
         }
     }
 
     public function testInvalidKey()
     {
+        if (version_compare(PHP_VERSION, '7.3.0', '>=')) {
+            $assertRegExp = 'assertMatchesRegularExpression';
+        } else {
+            $assertRegExp = 'assertRegExp';
+        }
+
         try {
-            $client = new Client(array(
+            new Client(array(
                 'key' => 'zzzzzzzz-zzzz-zzzz-zzzz-zzzzzzzzzzzz',
             ));
         } catch (\Exception $e) {
-            $this->assertRegExp('/invalid api key/i', $e->getMessage());
+            $this->$assertRegExp('/invalid api key/i', $e->getMessage());
         }
     }
 
     public function testVersionTooLow()
     {
+        if (version_compare(PHP_VERSION, '7.3.0', '>=')) {
+            $assertRegExp = 'assertMatchesRegularExpression';
+        } else {
+            $assertRegExp = 'assertRegExp';
+        }
+
         try {
-            $client = new Client(array('key' => self::KEY, 'version' => 0));
+            new Client(array('key' => self::KEY, 'version' => 0));
         } catch (\Exception $e) {
-            $this->assertRegExp('/invalid version/i', $e->getMessage());
+            $this->$assertRegExp('/invalid version/i', $e->getMessage());
         }
     }
 
     public function testVersionTooHigh()
     {
+        if (version_compare(PHP_VERSION, '7.3.0', '>=')) {
+            $assertRegExp = 'assertMatchesRegularExpression';
+        } else {
+            $assertRegExp = 'assertRegExp';
+        }
+
         try {
-            $client = new Client(array('key' => self::KEY, 'version' => 2));
+            new Client(array('key' => self::KEY, 'version' => 2));
         } catch (\Exception $e) {
-            $this->assertRegExp('/invalid version/i', $e->getMessage());
+            $this->$assertRegExp('/invalid version/i', $e->getMessage());
         }
     }
 
@@ -97,108 +113,6 @@ class ClientTest extends \PHPUnit_Framework_TestCase
         ), $client->countries());
     }
 
-    public function testSearchCountries()
-    {
-        $url = self::BASE_URL . 'countries?key=' . self::KEY . '&search=Sao';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'countries' => array(
-                            array(
-                                'code' => 'ST',
-                                'name' => 'Sao Tome and Principle',
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'countries' => array(
-                array(
-                    'code' => 'ST',
-                    'name' => 'Sao Tome and Principle',
-                ),
-            ),
-        ), $client->countries(array('search' => 'Sao')));
-    }
-
-    public function testReturnCountryByCode()
-    {
-        $url = self::BASE_URL . 'countries?key=' . self::KEY . '&country=ST';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'countries' => array(
-                            array(
-                                'code' => 'ST',
-                                'name' => 'Sao Tome and Principle',
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'countries' => array(
-                array(
-                    'code' => 'ST',
-                    'name' => 'Sao Tome and Principle',
-                ),
-            ),
-        ), $client->countries(array('country' => 'ST')));
-    }
-
-    public function testReturnCountryWithPublic()
-    {
-        $url = self::BASE_URL . 'countries?key=' . self::KEY . '&public=1';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'countries' => array(
-                            array(
-                                'code' => 'ST',
-                                'name' => 'Sao Tome and Principle',
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'countries' => array(
-                array(
-                    'code' => 'ST',
-                    'name' => 'Sao Tome and Principle',
-                ),
-            ),
-        ), $client->countries(array('public' => true)));
-    }
-
     public function testCountriesRaise4xxErrors()
     {
         $url = self::BASE_URL . 'countries?key=' . self::KEY;
@@ -255,8 +169,7 @@ class ClientTest extends \PHPUnit_Framework_TestCase
 
     public function testReturnHolidays()
     {
-        $url = self::BASE_URL . 'holidays?key=' . self::KEY
-            . '&country=US&year=2015&month=7&day=4';
+        $url = self::BASE_URL . 'holidays?key=' . self::KEY . '&country=US&year=2015&month=7&day=4';
 
         $request = new Request(array(
             'execute' => array(
@@ -297,89 +210,6 @@ class ClientTest extends \PHPUnit_Framework_TestCase
         )));
     }
 
-    public function testSearchHolidays()
-    {
-        $url = self::BASE_URL . 'holidays?key=' . self::KEY
-            . '&country=US&year=2015&search=Independence';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'holidays' => array(
-                            array(
-                                'name' => 'Independence Day',
-                                'date' => '2015-07-04',
-                                'observed' => '2015-07-03',
-                                'public' => true,
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'holidays' => array(
-                array(
-                    'name' => 'Independence Day',
-                    'date' => '2015-07-04',
-                    'observed' => '2015-07-03',
-                    'public' => true,
-                ),
-            ),
-        ), $client->holidays(array(
-            'country' => 'US',
-            'year' => 2015,
-            'search' => 'Independence',
-        )));
-    }
-
-    public function testCountryMissing()
-    {
-        $client = new Client(array('key' => self::KEY));
-
-        try {
-            $client->holidays(array('year' => 2015));
-        } catch (\Exception $e) {
-            $this->assertRegExp('/missing country/i', $e->getMessage());
-        }
-    }
-
-    public function testYearMissing()
-    {
-        $client = new Client(array('key' => self::KEY));
-
-        try {
-            $client->holidays(array('country' => 'US'));
-        } catch (\Exception $e) {
-            $this->assertRegExp('/missing year/i', $e->getMessage());
-        }
-    }
-
-    public function testBothPreviousAndUpcoming()
-    {
-        $client = new Client(array('key' => self::KEY));
-
-        try {
-            $client->holidays(array(
-                'country' => 'US',
-                'year' => 2015,
-                'month' => 7,
-                'day' => 4,
-                'upcoming' => true,
-                'previous' => true,
-            ));
-        } catch (\Exception $e) {
-            $this->assertRegExp('/previous and upcoming/i', $e->getMessage());
-        }
-    }
-
     public function testHolidaysRaise4xxErrors()
     {
         $url = self::BASE_URL . 'holidays?key=' . self::KEY . '&country=US&year=2019';
@@ -468,74 +298,6 @@ class ClientTest extends \PHPUnit_Framework_TestCase
         ), $client->languages());
     }
 
-    public function testSearchLanguages()
-    {
-        $url = self::BASE_URL . 'languages?key=' . self::KEY . '&search=Eng';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'languages' => array(
-                            array(
-                                'code' => 'en',
-                                'name' => 'English',
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'languages' => array(
-                array(
-                    'code' => 'en',
-                    'name' => 'English',
-                ),
-            ),
-        ), $client->languages(array('search' => 'Eng')));
-    }
-
-    public function testReturnLanguageByCode()
-    {
-        $url = self::BASE_URL . 'languages?key=' . self::KEY . '&language=en';
-
-        $request = new Request(array(
-            'execute' => array(
-                $url => function ()
-                {
-                    return json_encode(array(
-                        'status' => 200,
-                        'languages' => array(
-                            array(
-                                'code' => 'en',
-                                'name' => 'English',
-                            ),
-                        ),
-                    ));
-                },
-            ),
-        ));
-
-        $client = new Client(array('key' => self::KEY, 'handler' => $request));
-
-        $this->assertEquals(array(
-            'status' => 200,
-            'languages' => array(
-                array(
-                    'code' => 'en',
-                    'name' => 'English',
-                ),
-            ),
-        ), $client->languages(array('language' => 'en')));
-    }
-
     public function testLanguagesRaise4xxErrors()
     {
         $url = self::BASE_URL . 'languages?key=' . self::KEY;
@@ -589,5 +351,189 @@ class ClientTest extends \PHPUnit_Framework_TestCase
             $this->assertSame('Internal server error', $e->getMessage());
         }
     }
+
+    public function testReturnWorkday()
+    {
+        $url = self::BASE_URL . 'workday?key=' . self::KEY . '&country=US&start=2019-07-01&days=10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return json_encode(array(
+                        'status' => 200,
+                        'workday' => array(
+                            'date' => '2019-07-16',
+                        ),
+                    ));
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        $this->assertEquals(array(
+            'status' => 200,
+            'workday' => array(
+                'date' => '2019-07-16',
+            ),
+        ), $client->workday(array(
+            'country' => 'US',
+            'start' => '2019-07-01',
+            'days' => 10,
+        )));
+    }
+
+    public function testWorkdayRaise4xxErrors()
+    {
+        $url = self::BASE_URL . 'workday?key=' . self::KEY . '&country=US&start=2019-07-01&days=10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return json_encode(array(
+                        'status' => 429,
+                        'error' => 'Rate limit exceeded',
+                    ));
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        try {
+            $client->workday(array(
+                'country' => 'US',
+                'start' => '2019-07-01',
+                'days' => 10,
+            ));
+        } catch (\Exception $e) {
+            $this->assertSame(429, $e->getCode());
+            $this->assertSame('Rate limit exceeded', $e->getMessage());
+        }
+    }
+
+    public function testWorkdayRaise5xxErrors()
+    {
+        $url = self::BASE_URL . 'workday?key=' . self::KEY . '&country=US&start=2019-07-01&days=10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return false;
+                },
+            ),
+            'error' => array(
+                $url => function ()
+                {
+                    return 'Internal server error';
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        try {
+            $client->workday(array(
+                'country' => 'US',
+                'start' => '2019-07-01',
+                'days' => 10,
+            ));
+        } catch (\Exception $e) {
+            $this->assertSame('Internal server error', $e->getMessage());
+        }
+    }
+
+    public function testReturnWorkdays()
+    {
+        $url = self::BASE_URL . 'workdays?key=' . self::KEY . '&country=US&start=2019-07-01&end=2019-07-10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return json_encode(array(
+                        'status' => 200,
+                        'workdays' => 7,
+                    ));
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        $this->assertEquals(array(
+            'status' => 200,
+            'workdays' => 7,
+        ), $client->workdays(array(
+            'country' => 'US',
+            'start' => '2019-07-01',
+            'end' => '2019-07-10',
+        )));
+    }
+
+    public function testWorkdaysRaise4xxErrors()
+    {
+        $url = self::BASE_URL . 'workdays?key=' . self::KEY . '&country=US&start=2019-07-01&end=2019-07-10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return json_encode(array(
+                        'status' => 429,
+                        'error' => 'Rate limit exceeded',
+                    ));
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        try {
+            $client->workdays(array(
+                'country' => 'US',
+                'start' => '2019-07-01',
+                'end' => '2019-07-10',
+            ));
+        } catch (\Exception $e) {
+            $this->assertSame(429, $e->getCode());
+            $this->assertSame('Rate limit exceeded', $e->getMessage());
+        }
+    }
+
+    public function testWorkdaysRaise5xxErrors()
+    {
+        $url = self::BASE_URL . 'workdays?key=' . self::KEY . '&country=US&start=2019-07-01&end=2019-07-10';
+
+        $request = new Request(array(
+            'execute' => array(
+                $url => function ()
+                {
+                    return false;
+                },
+            ),
+            'error' => array(
+                $url => function ()
+                {
+                    return 'Internal server error';
+                },
+            ),
+        ));
+
+        $client = new Client(array('key' => self::KEY, 'handler' => $request));
+
+        try {
+            $client->workdays(array(
+                'country' => 'US',
+                'start' => '2019-07-01',
+                'end' => '2019-07-10',
+            ));
+        } catch (\Exception $e) {
+            $this->assertSame('Internal server error', $e->getMessage());
+        }
+    }
 }
 
diff --git a/tests/RequestTest.php b/tests/RequestTest.php
index 31594f3..f42776d 100644
--- a/tests/RequestTest.php
+++ b/tests/RequestTest.php
@@ -1,18 +1,9 @@
 <?php
 namespace HolidayAPI\Tests;
-use HolidayAPI\Client;
 use HolidayAPI\Request;
+use PHPUnit\Framework\TestCase;
 
-require __DIR__ . '/../vendor/autoload.php';
-
-if (
-    !class_exists('\PHPUnit_Framework_TestCase')
-    && class_exists('\PHPUnit\Framework\TestCase')
-) {
-    class_alias('\PHPUnit\Framework\TestCase', '\PHPUnit_Framework_TestCase');
-}
-
-class RequestTest extends \PHPUnit_Framework_TestCase
+class RequestTest extends TestCase
 {
     public function testExecute()
     {
@@ -24,6 +15,12 @@ class RequestTest extends \PHPUnit_Framework_TestCase
 
     public function testGet()
     {
+        if (version_compare(PHP_VERSION, '7.3.0', '>=')) {
+            $assertRegExp = 'assertMatchesRegularExpression';
+        } else {
+            $assertRegExp = 'assertRegExp';
+        }
+
         $url = 'https://holidayapi.com';
 
         $request = new Request(array(
@@ -38,7 +35,7 @@ class RequestTest extends \PHPUnit_Framework_TestCase
         try {
             $request->get($url);
         } catch (\Exception $e) {
-            $this->assertRegExp('/empty response/i', $e->getMessage());
+            $this->$assertRegExp('/empty response/i', $e->getMessage());
         }
     }
 }