diff --git a/lib/active_merchant/billing/gateways/nuvei.rb b/lib/active_merchant/billing/gateways/nuvei.rb
index 4410c5b443a..f2c6c1df87f 100644
--- a/lib/active_merchant/billing/gateways/nuvei.rb
+++ b/lib/active_merchant/billing/gateways/nuvei.rb
@@ -27,10 +27,10 @@ def initialize(options = {})
         fetch_session_token unless session_token_valid?
       end
 
-      def authorize(money, payment, options = {})
-        post = { transactionType: 'Auth' }
+      def authorize(money, payment, options = {}, transaction_type = 'Auth')
+        post = { transactionType: transaction_type }
 
-        build_post_data(post, :authorize)
+        build_post_data(post)
         add_amount(post, money, options)
         add_payment_method(post, payment)
         add_address(post, payment, options)
@@ -39,22 +39,53 @@ def authorize(money, payment, options = {})
         commit(:purchase, post)
       end
 
-      def purchase(money, payment, options = {}); end
+      def purchase(money, payment, options = {})
+        authorize(money, payment, options, 'Sale')
+      end
 
       def capture(money, authorization, options = {})
         post = { relatedTransactionId: authorization }
 
-        build_post_data(post, :capture)
+        build_post_data(post)
         add_amount(post, money, options)
 
         commit(:capture, post)
       end
 
-      def refund(money, authorization, options = {}); end
+      def refund(money, authorization, options = {})
+        post = { relatedTransactionId: authorization }
+
+        build_post_data(post)
+        add_amount(post, money, options)
+
+        commit(:refund, post)
+      end
 
-      def void(authorization, options = {}); end
+      def void(authorization, options = {})
+        post = { relatedTransactionId: authorization }
+        build_post_data(post)
 
-      def credit(money, payment, options = {}); end
+        commit(:void, post)
+      end
+
+      def verify(credit_card, options = {})
+        MultiResponse.run(:use_first_response) do |r|
+          r.process { authorize(0, credit_card, options) }
+          r.process(:ignore_result) { void(r.authorization, options) }
+        end
+      end
+
+      def credit(money, payment, options = {})
+        post = { userTokenId: options[:user_token_id] }
+
+        build_post_data(post)
+        add_amount(post, money, options)
+        add_payment_method(post, payment, :cardData)
+        add_address(post, payment, options)
+        add_customer_ip(post, options)
+
+        commit(:general_credit, post.compact)
+      end
 
       def supports_scrubbing?
         true
@@ -93,12 +124,9 @@ def credit_card_hash(payment)
         }
       end
 
-      def add_payment_method(post, payment)
-        if payment.is_a?(CreditCard)
-          post[:paymentOption] = { card: credit_card_hash(payment) }
-        else
-          post[:paymentOption] = { card: { cardToken: payment } }
-        end
+      def add_payment_method(post, payment, key = :paymentOption)
+        payment_data = payment.is_a?(CreditCard) ? credit_card_hash(payment) : { cardToken: payment }
+        post[key] = key == :cardData ? payment_data : { card: payment_data }
       end
 
       def add_customer_names(full_name, payment_method)
@@ -126,7 +154,7 @@ def current_timestamp
         Time.now.utc.strftime('%Y%m%d%H%M%S')
       end
 
-      def build_post_data(post, action)
+      def build_post_data(post)
         post[:merchantId] = @options[:merchant_id]
         post[:merchantSiteId] = @options[:merchant_site_id]
         post[:timeStamp] = current_timestamp.to_i
@@ -139,7 +167,7 @@ def calculate_checksum(post, action)
         keys = case action
                when :authenticate
                  [:timeStamp]
-               when :capture
+               when :capture, :refund, :void
                  %i[clientUniqueId amount currency relatedTransactionId timeStamp]
                else
                  %i[amount currency timeStamp]
@@ -161,12 +189,12 @@ def send_session_request(post)
           message_from(response),
           response,
           test: test?,
-          error_code: response[:errCode]
+          error_code: error_code_from(response)
         )
       end
 
       def fetch_session_token(post = {})
-        build_post_data(post, :authenticate)
+        build_post_data(post)
         send_session_request(post)
       end
 
@@ -188,7 +216,7 @@ def commit(action, post, authorization = nil, method = :post)
           response,
           authorization: authorization_from(action, response, post),
           test: test?,
-          error_code: error_code_from(action, response)
+          error_code: error_code_from(response)
         )
       rescue ResponseError => e
         response = parse(e.response.body)
@@ -201,8 +229,8 @@ def url(action, id = nil)
         "#{test? ? test_url : live_url}#{ENDPOINTS_MAPPING[action] % id}"
       end
 
-      def error_code_from(action, response)
-        (response[:statusName] || response[:status]) unless success_from(response)
+      def error_code_from(response)
+        response[:errCode] == 0 ? response[:gwErrorCode] : response[:errCode]
       end
 
       def headers
@@ -231,7 +259,8 @@ def authorization_from(action, response, post)
       end
 
       def message_from(response)
-        response[:status]
+        reason = response[:reason]&.present? ? response[:reason] : nil
+        response[:gwErrorReason] || reason || response[:transactionStatus]
       end
     end
   end
diff --git a/test/remote/gateways/remote_nuvei_test.rb b/test/remote/gateways/remote_nuvei_test.rb
index 5aa64a28f08..51f1ceae5cb 100644
--- a/test/remote/gateways/remote_nuvei_test.rb
+++ b/test/remote/gateways/remote_nuvei_test.rb
@@ -12,36 +12,8 @@ def setup
     @options = {
       email: 'test@gmail.com',
       billing_address: address.merge(name: 'Cure Tester'),
-      ip_address: '127.0.0.1'
+      ip: '127.0.0.1'
     }
-
-    @post = {
-      merchantId: 'test_merchant_id',
-      merchantSiteId: 'test_merchant_site_id',
-      clientRequestId: 'test_client_request_id',
-      amount: 'test_amount',
-      currency: 'test_currency',
-      timeStamp: 'test_time_stamp'
-    }
-  end
-
-  def test_calculate_checksum
-    expected_checksum = Digest::SHA256.hexdigest("test_merchant_idtest_merchant_site_idtest_client_request_idtest_amounttest_currencytest_time_stamp#{@gateway.options[:secret_key]}")
-    assert_equal expected_checksum, @gateway.send(:calculate_checksum, @post, :purchase)
-  end
-
-  def test_calculate_checksum_authenticate
-    expected_checksum = Digest::SHA256.hexdigest("test_merchant_idtest_merchant_site_idtest_client_request_idtest_time_stamp#{@gateway.options[:secret_key]}")
-    @post.delete(:amount)
-    @post.delete(:currency)
-    assert_equal expected_checksum, @gateway.send(:calculate_checksum, @post, :authenticate)
-  end
-
-  def test_calculate_checksum_capture
-    expected_checksum = Digest::SHA256.hexdigest("test_merchant_idtest_merchant_site_idtest_client_request_idtest_client_idtest_amounttest_currencytest_transaction_idtest_time_stamp#{@gateway.options[:secret_key]}")
-    @post[:clientUniqueId] = 'test_client_id'
-    @post[:relatedTransactionId] = 'test_transaction_id'
-    assert_equal expected_checksum, @gateway.send(:calculate_checksum, @post, :capture)
   end
 
   def test_transcript_scrubbing
@@ -62,16 +34,14 @@ def test_failed_session_token_generation
     @gateway.options[:merchant_site_id] = 123
     response = @gateway.send(:fetch_session_token, {})
     assert_failure response
-    assert_match 'ERROR', response.message
-    assert_match 'Invalid merchant site id', response.params['reason']
+    assert_match 'Invalid merchant site id', response.message
   end
 
   def test_successful_authorize
     response = @gateway.authorize(@amount, @credit_card, @options)
     assert_success response
     assert_not_nil response.params[:transactionId]
-    assert_match 'SUCCESS', response.message
-    assert_match 'APPROVED', response.params['transactionStatus']
+    assert_match 'APPROVED', response.message
   end
 
   def test_failed_authorize
@@ -87,14 +57,89 @@ def test_successful_authorize_and_capture
     capture_response = @gateway.capture(@amount, response.authorization)
 
     assert_success capture_response
-    assert_match 'SUCCESS', capture_response.message
-    assert_match 'APPROVED', capture_response.params['transactionStatus']
+    assert_match 'APPROVED', capture_response.message
   end
 
   def test_successful_zero_auth
     response = @gateway.authorize(0, @credit_card, @options)
     assert_success response
-    assert_match 'SUCCESS', response.message
-    assert_match 'APPROVED', response.params['transactionStatus']
+    assert_match 'APPROVED', response.message
+  end
+
+  def test_successful_purchase
+    response = @gateway.purchase(@amount, @credit_card, @options)
+    assert_success response
+    assert_not_nil response.params[:transactionId]
+    assert_match 'APPROVED', response.message
+    assert_match 'SUCCESS', response.params['status']
+  end
+
+  def test_failed_purchase
+    response = @gateway.purchase(@amount, @declined_card, @options)
+    assert_failure response
+    assert_match 'DECLINED', response.params['transactionStatus']
+  end
+
+  def test_failed_purchase_with_invalid_cvv
+    @credit_card.verification_value = nil
+    response = @gateway.purchase(@amount, @credit_card, @options)
+    assert_failure response
+    assert_match 'ERROR', response.params['transactionStatus']
+    assert_match 'Invalid CVV2', response.message
+  end
+
+  def test_failed_capture_invalid_transaction_id
+    response = @gateway.capture(@amount, '123')
+    assert_failure response
+    assert_match 'ERROR', response.params['status']
+    assert_match 'Invalid relatedTransactionId', response.message
+  end
+
+  def test_successful_void
+    response = @gateway.authorize(@amount, @credit_card, @options)
+    assert_success response
+
+    void_response = @gateway.void(response.authorization)
+    assert_success void_response
+    assert_match 'SUCCESS', void_response.params['status']
+    assert_match 'APPROVED', void_response.message
+  end
+
+  def test_failed_void_invalid_transaction_id
+    response = @gateway.void('123')
+    assert_failure response
+    assert_match 'ERROR', response.params['status']
+    assert_match 'Invalid relatedTransactionId', response.message
+  end
+
+  def test_successful_refund
+    response = @gateway.purchase(@amount, @credit_card, @options)
+    assert_success response
+
+    refund_response = @gateway.refund(@amount, response.authorization)
+    assert_success refund_response
+    assert_match 'SUCCESS', refund_response.params['status']
+    assert_match 'APPROVED', refund_response.message
+  end
+
+  def test_successful_verify
+    response = @gateway.verify(@credit_card, @options)
+    assert_success response
+    assert_match 'SUCCESS', response.params['status']
+    assert_match 'APPROVED', response.message
+  end
+
+  def test_successful_general_credit
+    credit_response = @gateway.credit(@amount, @credit_card, @options.merge!(user_token_id: '123'))
+    assert_success credit_response
+    assert_match 'SUCCESS', credit_response.params['status']
+    assert_match 'APPROVED', credit_response.message
+  end
+
+  def test_failed_general_credit
+    credit_response = @gateway.credit(@amount, @declined_card, @options)
+    assert_failure credit_response
+    assert_match 'ERROR', credit_response.params['status']
+    assert_match 'Invalid user token', credit_response.message
   end
 end
diff --git a/test/unit/gateways/nuvei_test.rb b/test/unit/gateways/nuvei_test.rb
index c3a07c68327..d19d19981ef 100644
--- a/test/unit/gateways/nuvei_test.rb
+++ b/test/unit/gateways/nuvei_test.rb
@@ -77,6 +77,44 @@ def test_successful_authorize
     end.respond_with(successful_authorize_response)
   end
 
+  def test_successful_purchase
+    stub_comms(@gateway, :ssl_request) do
+      @gateway.purchase(@amount, @credit_card, @options)
+    end.check_request do |_method, endpoint, data, _headers|
+      if /payment/.match?(endpoint)
+        json_data = JSON.parse(data)
+        assert_match(/#{@amount}/, json_data['amount'])
+        assert_match(/#{@credit_card.number}/, json_data['paymentOption']['card']['cardNumber'])
+        assert_match(/#{@credit_card.verification_value}/, json_data['paymentOption']['card']['CVV'])
+        assert_match(%r(/payment), endpoint)
+      end
+    end.respond_with(successful_purchase_response)
+  end
+
+  def test_successful_refund
+    stub_comms(@gateway, :ssl_request) do
+      @gateway.refund(@amount, '123456', @options)
+    end.check_request(skip_response: true) do |_method, endpoint, data, _headers|
+      json_data = JSON.parse(data)
+      if /refundTransaction/.match?(endpoint)
+        assert_match(/123456/, json_data['relatedTransactionId'])
+        assert_match(/#{@amount}/, json_data['amount'])
+      end
+    end
+  end
+
+  def test_successful_credit
+    stub_comms(@gateway, :ssl_request) do
+      @gateway.credit(@amount, @credit_card, @options)
+    end.check_request do |_method, endpoint, data, _headers|
+      json_data = JSON.parse(data)
+      if /payout/.match?(endpoint)
+        assert_match(/#{@amount}/, json_data['amount'])
+        assert_match(/#{@credit_card.number}/, json_data['cardData']['cardNumber'])
+      end
+    end.respond_with(successful_purchase_response)
+  end
+
   private
 
   def pre_scrubbed
@@ -140,4 +178,10 @@ def successful_authorize_response
       {"internalRequestId":1171104468,"status":"SUCCESS","errCode":0,"reason":"","merchantId":"3755516963854600967","merchantSiteId":"255388","version":"1.0","clientRequestId":"02ba666c-e3e5-4ec9-ae30-3f8500b18c96","sessionToken":"29226538-82c7-4a3c-b363-cb6829b8c32a","clientUniqueId":"c00ed73a7d682bf478295d57bdae3028","orderId":"471361708","paymentOption":{"userPaymentOptionId":"","card":{"ccCardNumber":"4****1390","bin":"476134","last4Digits":"1390","ccExpMonth":"09","ccExpYear":"25","acquirerId":"19","cvv2Reply":"","avsCode":"","cardType":"Debit","cardBrand":"VISA","issuerBankName":"INTL HDQTRS-CENTER OWNED","issuerCountry":"SG","isPrepaid":"false","threeD":{},"processedBrand":"VISA"},"paymentAccountReference":"f4iK2pnudYKvTALGdcwEzqj9p4"},"transactionStatus":"APPROVED","gwErrorCode":0,"gwExtendedErrorCode":0,"issuerDeclineCode":"","issuerDeclineReason":"","transactionType":"Auth","transactionId":"7110000000001908486","externalTransactionId":"","authCode":"111397","customData":"","fraudDetails":{"finalDecision":"Accept","score":"0"},"externalSchemeTransactionId":"","merchantAdviceCode":""}
     RESPONSE
   end
+
+  def successful_purchase_response
+    <<~RESPONSE
+      {"internalRequestId":1172848838, "status":"SUCCESS", "errCode":0, "reason":"", "merchantId":"3755516963854600967", "merchantSiteId":"255388", "version":"1.0", "clientRequestId":"a114381a-0f88-46d0-920c-7b5614f29e5b", "sessionToken":"d3424c9c-dd6d-40dc-85da-a2b92107cbe3", "clientUniqueId":"3ba2a81c46d78837ea819d9f3fe644e7", "orderId":"471833818", "paymentOption":{"userPaymentOptionId":"", "card":{"ccCardNumber":"4****1390", "bin":"476134", "last4Digits":"1390", "ccExpMonth":"09", "ccExpYear":"25", "acquirerId":"19", "cvv2Reply":"", "avsCode":"", "cardType":"Debit", "cardBrand":"VISA", "issuerBankName":"INTL HDQTRS-CENTER OWNED", "issuerCountry":"SG", "isPrepaid":"false", "threeD":{}, "processedBrand":"VISA"}, "paymentAccountReference":"f4iK2pnudYKvTALGdcwEzqj9p4"}, "transactionStatus":"APPROVED", "gwErrorCode":0, "gwExtendedErrorCode":0, "issuerDeclineCode":"", "issuerDeclineReason":"", "transactionType":"Sale", "transactionId":"7110000000001990927", "externalTransactionId":"", "authCode":"111711", "customData":"", "fraudDetails":{"finalDecision":"Accept", "score":"0"}, "externalSchemeTransactionId":"", "merchantAdviceCode":""}
+    RESPONSE
+  end
 end