diff --git a/.env.example b/.env.example
index cb09d8b..af23d78 100644
--- a/.env.example
+++ b/.env.example
@@ -1,3 +1,3 @@
 BF_IPFS_PROJECT_ID=
 BF_MAINNET_PROJECT_ID=
-BF_TESTNET_PROJECT_ID=
\ No newline at end of file
+BF_TESTNET_PROJECT_ID=
diff --git a/lib/blockfrostruby/endpoints/cardano/health_endpoints.rb b/lib/blockfrostruby/endpoints/cardano/health_endpoints.rb
index fb28dc5..2160fa5 100644
--- a/lib/blockfrostruby/endpoints/cardano/health_endpoints.rb
+++ b/lib/blockfrostruby/endpoints/cardano/health_endpoints.rb
@@ -16,7 +16,7 @@ def get_root
   #
   # @return [Hash] formatted result with status and body keys.
   def get_health
-    Request.get_response("#{@url}/health", @project_id)
+    Request.get_response("#{@url}/health")
   end
 
   # Calls get request on (@url)/health/clock.
diff --git a/lib/blockfrostruby/request.rb b/lib/blockfrostruby/request.rb
index 3e21f42..740b0fe 100644
--- a/lib/blockfrostruby/request.rb
+++ b/lib/blockfrostruby/request.rb
@@ -17,7 +17,7 @@ class << self
     # @param project_id [String] the project_id to pass to url in headers.
     # @param params [Hash] params to add to request, allowed :order, :page, :count, :from, :to.
     # @return [Hash] formatted result with status and body keys.
-    def get_response(url, project_id, params = {})
+    def get_response(url, project_id = nil, params = {})
       params[:from_page] ? get_pages_multi(url, project_id, params) : get_response_from_url(url, project_id, params)
     end
 
diff --git a/spec/endpoints/assets_endpoints_spec.rb b/spec/endpoints/assets_endpoints_spec.rb
index 7889f71..54b693d 100644
--- a/spec/endpoints/assets_endpoints_spec.rb
+++ b/spec/endpoints/assets_endpoints_spec.rb
@@ -45,9 +45,9 @@
         end
 
         context 'with invalid asset' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_specific_asset(invalid_asset)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -72,16 +72,16 @@
 
         context 'with invalid asset' do
           context 'without params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_history(invalid_asset)
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
           context 'with params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_history(invalid_asset, { count: 7, page: 3 })
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
@@ -107,16 +107,16 @@
 
         context 'with invalid asset' do
           context 'without params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_transactions(invalid_asset)
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
           context 'with params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_transactions(invalid_asset, { count: 7, page: 3 })
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
@@ -142,16 +142,16 @@
 
         context 'with invalid asset' do
           context 'without params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_addresses(invalid_asset)
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
           context 'with params' do
-            it 'returns status 404, response body includes error' do
+            it 'returns status 400, response body includes error' do
               response = blockfrost_mainnet.get_asset_addresses(invalid_asset, { count: 7, page: 3 })
-              expect(response[:status]).to eq(404)
+              expect(response[:status]).to eq(400)
               expect(response[:body]).to include(:error)
             end
           end
@@ -177,16 +177,16 @@
 
       context 'with invalid policy_id' do
         context 'without params' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_assets_of_policy(invalid_policy_id)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
         context 'with params' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_assets_of_policy(invalid_policy_id, { count: 7, page: 3 })
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
diff --git a/spec/endpoints/blocks_endpoints_spec.rb b/spec/endpoints/blocks_endpoints_spec.rb
index 790f40b..45c7fe6 100644
--- a/spec/endpoints/blocks_endpoints_spec.rb
+++ b/spec/endpoints/blocks_endpoints_spec.rb
@@ -49,9 +49,9 @@
           end
         end
         context 'with invalid hash_or_number' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_block(invalid_hash_or_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -65,10 +65,9 @@
           end
         end
         context 'with invalid slot number' do
-          it 'returns status 404, response body includes error' do
-            skip 'Returns 500 instead of 404'
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_block_in_slot(invalid_slot_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -82,10 +81,9 @@
           end
         end
         context 'with invalid slot and epoch number' do
-          it 'returns status 404, response body includes error' do
-            skip 'Returns 500 instead of 404'
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_block_in_slot_in_epoch(invalid_slot_number, invalid_epoch_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -109,9 +107,9 @@
           end
         end
         context 'with invalid hash_or_number' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_list_of_next_blocks(invalid_hash_or_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -135,9 +133,9 @@
           end
         end
         context 'with invalid hash_or_number' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_list_of_previous_blocks(invalid_hash_or_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
@@ -161,9 +159,9 @@
           end
         end
         context 'with invalid hash_or_number' do
-          it 'returns status 404, response body includes error' do
+          it 'returns status 400, response body includes error' do
             response = blockfrost_mainnet.get_block_transactions(invalid_hash_or_number)
-            expect(response[:status]).to eq(404)
+            expect(response[:status]).to eq(400)
             expect(response[:body]).to include(:error)
           end
         end
diff --git a/spec/endpoints/health_endpoints_spec.rb b/spec/endpoints/health_endpoints_spec.rb
index a985b35..dc72570 100644
--- a/spec/endpoints/health_endpoints_spec.rb
+++ b/spec/endpoints/health_endpoints_spec.rb
@@ -7,8 +7,8 @@
 RSpec.describe HealthEndpoints do
   let(:blockfrost_mainnet) { Blockfrostruby::CardanoMainNet.new(ENV['BF_MAINNET_PROJECT_ID']) }
   let(:blockfrost_mainnet_invalid) { Blockfrostruby::CardanoMainNet.new('invalid project_id') }
-  let(:blockfrost_testnet) { Blockfrostruby::CardanoTestNet.new(ENV['BF_TESTNET_PROJECT_ID']) }
-  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoTestNet.new('invalid project_id') }
+  let(:blockfrost_testnet) { Blockfrostruby::CardanoPreview.new(ENV['BF_TESTNET_PROJECT_ID']) }
+  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoPreview.new('invalid project_id') }
 
   context 'CardanoMainNet object' do
     context 'with valid project_id' do
@@ -39,16 +39,16 @@
 
     context 'with invalid project_id' do
       context 'when calls get_health method' do
-        it 'returns 403 status and body includes error' do
+        it 'return status 200 and is_healthy => true' do
           response = blockfrost_mainnet_invalid.get_health
-          expect(response[:status]).to eq(403)
-          expect(response[:body]).to include(:error)
+          expect(response[:status]).to eq(200)
+          expect(response[:body]).to eq({ is_healthy: true })
         end
       end
     end
   end
 
-  context 'CardanoTestNet object' do
+  context 'CardanoPreview object' do
     context 'with valid project_id' do
       context 'when calls get_health method' do
         it 'return status 200 and is_healthy => true' do
@@ -77,10 +77,10 @@
 
     context 'with invalid project_id' do
       context 'when calls get_health method' do
-        it 'returns 403 status and body includes error' do
+        it 'return status 200 and is_healthy => true' do
           response = blockfrost_testnet_invalid.get_health
-          expect(response[:status]).to eq(403)
-          expect(response[:body]).to include(:error)
+          expect(response[:status]).to eq(200)
+          expect(response[:body]).to eq({ is_healthy: true })
         end
       end
     end
diff --git a/spec/endpoints/ledger_endpoints_spec.rb b/spec/endpoints/ledger_endpoints_spec.rb
index a4de8cb..03cfe68 100644
--- a/spec/endpoints/ledger_endpoints_spec.rb
+++ b/spec/endpoints/ledger_endpoints_spec.rb
@@ -7,8 +7,8 @@
 RSpec.describe LedgerEndpoints do
   let(:blockfrost_mainnet) { Blockfrostruby::CardanoMainNet.new(ENV['BF_MAINNET_PROJECT_ID']) }
   let(:blockfrost_mainnet_invalid) { Blockfrostruby::CardanoMainNet.new('invalid project_id') }
-  let(:blockfrost_testnet) { Blockfrostruby::CardanoTestNet.new(ENV['BF_TESTNET_PROJECT_ID']) }
-  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoTestNet.new('invalid project_id') }
+  let(:blockfrost_testnet) { Blockfrostruby::CardanoPreview.new(ENV['BF_TESTNET_PROJECT_ID']) }
+  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoPreview.new('invalid project_id') }
 
   context 'CardanoMainNet object' do
     context 'with valid project_id' do
@@ -32,7 +32,7 @@
     end
   end
 
-  context 'CardanoTestNet object' do
+  context 'CardanoPreview object' do
     context 'with valid project_id' do
       context 'when calls get_genesis method' do
         it 'return status 200 and response body includes active_slots_coefficient' do
diff --git a/spec/endpoints/metrics_endpoints_spec.rb b/spec/endpoints/metrics_endpoints_spec.rb
index 08f99e9..b48205c 100644
--- a/spec/endpoints/metrics_endpoints_spec.rb
+++ b/spec/endpoints/metrics_endpoints_spec.rb
@@ -7,8 +7,8 @@
 RSpec.describe MetricsEndpoints do
   let(:blockfrost_mainnet) { Blockfrostruby::CardanoMainNet.new(ENV['BF_MAINNET_PROJECT_ID']) }
   let(:blockfrost_mainnet_invalid) { Blockfrostruby::CardanoMainNet.new('invalid project_id') }
-  let(:blockfrost_testnet) { Blockfrostruby::CardanoTestNet.new(ENV['BF_TESTNET_PROJECT_ID']) }
-  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoTestNet.new('invalid project_id') }
+  let(:blockfrost_testnet) { Blockfrostruby::CardanoPreview.new(ENV['BF_TESTNET_PROJECT_ID']) }
+  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoPreview.new('invalid project_id') }
 
   context 'CardanoMainNet object' do
     context 'with valid project_id' do
@@ -38,7 +38,7 @@
     end
   end
 
-  context 'CardanoTestNet object' do
+  context 'CardanoPreview object' do
     context 'with valid project_id' do
       context 'when calls get_metrics method' do
         it 'return status 200' do
diff --git a/spec/endpoints/network_endpoints_spec.rb b/spec/endpoints/network_endpoints_spec.rb
index 98b36b3..29f04a3 100644
--- a/spec/endpoints/network_endpoints_spec.rb
+++ b/spec/endpoints/network_endpoints_spec.rb
@@ -7,8 +7,8 @@
 RSpec.describe NetworkEndpoints do
   let(:blockfrost_mainnet) { Blockfrostruby::CardanoMainNet.new(ENV['BF_MAINNET_PROJECT_ID']) }
   let(:blockfrost_mainnet_invalid) { Blockfrostruby::CardanoMainNet.new('invalid project_id') }
-  let(:blockfrost_testnet) { Blockfrostruby::CardanoTestNet.new(ENV['BF_TESTNET_PROJECT_ID']) }
-  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoTestNet.new('invalid project_id') }
+  let(:blockfrost_testnet) { Blockfrostruby::CardanoPreview.new(ENV['BF_TESTNET_PROJECT_ID']) }
+  let(:blockfrost_testnet_invalid) { Blockfrostruby::CardanoPreview.new('invalid project_id') }
 
   context 'CardanoMainNet object' do
     context 'with valid project_id' do
diff --git a/spec/endpoints/nutlink_endpoints_spec.rb b/spec/endpoints/nutlink_endpoints_spec.rb
index 8d48fdb..b409f45 100644
--- a/spec/endpoints/nutlink_endpoints_spec.rb
+++ b/spec/endpoints/nutlink_endpoints_spec.rb
@@ -6,19 +6,17 @@
 
 RSpec.describe NutlinkEndpoints do
   let(:blockfrost_mainnet) { Blockfrostruby::CardanoMainNet.new(ENV['BF_MAINNET_PROJECT_ID']) }
-  let(:blockfrost_mainnet_invalid) { Blockfrostruby::CardanoMainNet.new('invalid project_id') }
 
-  let(:valid_address) { 'addr1qxqs59lphg8g6qndelq8xwqn60ag3aeyfcp33c2kdp46a09re5df3pzwwmyq946axfcejy5n4x0y99wqpgtp2gd0k09qsgy6pz' }
-  let(:invalid_address) { 'invalid_number' }
-  let(:valid_ticker) { 'valid_ticker' }
-  let(:invalid_ticker) { 'invalid_number' }
+  let(:valid_address) { 'addr1q85yx2w7ragn5sx6umgmtjpc3865s9sg59sz4rrh6f90kgwfwlzu3w8ttacqg89mkdgwshwnplj5c5n9f8dhp0h55q2q7qm63t' }
+  let(:invalid_address) { 'invalid' }
+  let(:valid_ticker) { 'ADABTC' }
+  let(:invalid_ticker) { 'invalid' }
 
   context 'CardanoMainNet object' do
     context 'with valid project_id' do
       context 'when calls get_address_metadata_list method' do
         context 'with valid address' do
           it 'returns status 200' do
-            skip 'Return 404 now'
             response = blockfrost_mainnet.get_address_metadata_list(valid_address)
             expect(response[:status]).to eq(200)
           end
@@ -36,14 +34,12 @@
         context 'with valid address' do
           context 'without params' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_address_metadata_tickers_list(valid_address)
               expect(response[:status]).to eq(200)
             end
           end
           context 'with params { count: 5 }' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_address_metadata_tickers_list(valid_address, { count: 5 })
               expect(response[:status]).to eq(200)
             end
@@ -62,14 +58,12 @@
         context 'with valid address and ticker' do
           context 'without params' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_ticker_records_by_address(valid_address, valid_ticker)
               expect(response[:status]).to eq(200)
             end
           end
           context 'with params { count: 5 }' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_ticker_records_by_address(valid_address, valid_ticker, { count: 5 })
               expect(response[:status]).to eq(200)
             end
@@ -88,14 +82,12 @@
         context 'with valid address and ticker' do
           context 'without params' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_ticker_records(valid_ticker)
               expect(response[:status]).to eq(200)
             end
           end
           context 'with params { count: 5 }' do
             it 'returns status 200' do
-              skip 'Return 404 now'
               response = blockfrost_mainnet.get_ticker_records(valid_ticker, { count: 5 })
               expect(response[:status]).to eq(200)
             end