diff --git a/Software/E_Libra/DataAccessLayer/DataAccessLayer.csproj b/Software/E_Libra/DataAccessLayer/DataAccessLayer.csproj
index d60bcef..9e097e4 100644
--- a/Software/E_Libra/DataAccessLayer/DataAccessLayer.csproj
+++ b/Software/E_Libra/DataAccessLayer/DataAccessLayer.csproj
@@ -37,6 +37,9 @@
     <Reference Include="EntityFramework.SqlServer, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089, processorArchitecture=MSIL">
       <HintPath>..\packages\EntityFramework.6.2.0\lib\net45\EntityFramework.SqlServer.dll</HintPath>
     </Reference>
+    <Reference Include="Newtonsoft.Json, Version=13.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
+      <HintPath>..\packages\Newtonsoft.Json.13.0.3\lib\net45\Newtonsoft.Json.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.ComponentModel.DataAnnotations" />
     <Reference Include="System.Core" />
diff --git a/Software/E_Libra/DataAccessLayer/F16/GPTRequestSender.cs b/Software/E_Libra/DataAccessLayer/F16/GPTRequestSender.cs
index 7123f9a..a00788e 100644
--- a/Software/E_Libra/DataAccessLayer/F16/GPTRequestSender.cs
+++ b/Software/E_Libra/DataAccessLayer/F16/GPTRequestSender.cs
@@ -1,7 +1,10 @@
 using EntitiesLayer.F16;
+using Newtonsoft.Json;
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net.Http;
+using System.Net.Http.Headers;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -9,11 +12,64 @@ namespace DataAccessLayer.F16
 {
     public class GPTRequestSender : IGPTRequestSender
     {
+        private const string uri = "https://api.openai.com/v1/chat/completions";
+        private string apiKey { get; set; }
+
+        public GPTRequestSender(string apiKey)
+        {
+            this.apiKey = apiKey;
+        }
+
         public async Task<string> SendRequest(GPTRequest request)
         {
-            await Task.Delay(100);
+            var requestPayload = CreatePayloadFromRequest(request);
+
+            using (var client = new HttpClient())
+            {
+                var endpoint = new Uri(uri);
+                client.DefaultRequestHeaders.Add("Authorization", $"Bearer {apiKey}");
+                client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+
+                var response = await client.PostAsync(endpoint, requestPayload);
+                if (!response.IsSuccessStatusCode)
+                {
+                    return "Dogodila se greška kod dohvata odgovora.";
+                }
+
+                //var responseContent = await response.Content.ReadAsStringAsync();
+                return await GetAnswerFromResponseContent(response.Content);
+            }
+        }
+
+        private StringContent CreatePayloadFromRequest(GPTRequest request)
+        {
+            var requestJson = JsonConvert.SerializeObject(request);
+            return new StringContent(requestJson, Encoding.UTF8, "application/json");
+        }
+
+        private async Task<string> GetAnswerFromResponseContent(HttpContent content)
+        {
+            var contentString = await content.ReadAsStringAsync();
+            GPTResponse responseObject = JsonConvert.DeserializeObject<GPTResponse>(contentString);
+            if (responseObject.choices == null)
+            {
+                return "Dogodila se greška kod čitanja odgovora.";
+            }
+
+            var choices = responseObject.choices;
+            if (choices.Count == 0)
+            {
+                return "Nisu dobiveni nikakvi odgovori.";
+            }
+
+            var firstChoice = choices[0];
+            var choiceMessage = firstChoice.message;
+            if (choiceMessage == null)
+            {
+                return "Dogodila se greška.";
+            }
 
-            return new GPTResponse().ToString();
+            return choiceMessage.content;
         }
     }
 }
diff --git a/Software/E_Libra/DataAccessLayer/packages.config b/Software/E_Libra/DataAccessLayer/packages.config
index f1df1d6..878ff30 100644
--- a/Software/E_Libra/DataAccessLayer/packages.config
+++ b/Software/E_Libra/DataAccessLayer/packages.config
@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
   <package id="EntityFramework" version="6.2.0" targetFramework="net48" />
+  <package id="Newtonsoft.Json" version="13.0.3" targetFramework="net48" />
 </packages>
\ No newline at end of file
diff --git a/Software/E_Libra/EntitiesLayer/EntitiesLayer.csproj b/Software/E_Libra/EntitiesLayer/EntitiesLayer.csproj
index 6818e00..80ace87 100644
--- a/Software/E_Libra/EntitiesLayer/EntitiesLayer.csproj
+++ b/Software/E_Libra/EntitiesLayer/EntitiesLayer.csproj
@@ -68,6 +68,7 @@
     <Compile Include="Entities\Member.cs" />
     <Compile Include="Entities\MostPopularBooks.cs" />
     <Compile Include="Entities\MostPopularGenres.cs" />
+    <Compile Include="F16\GPTChoices.cs" />
     <Compile Include="F16\GPTMessage.cs" />
     <Compile Include="F16\GPTRequest.cs" />
     <Compile Include="F16\GPTResponse.cs" />
diff --git a/Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/Class1.cs b/Software/E_Libra/EntitiesLayer/F16/GPTChoices.cs
similarity index 56%
rename from Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/Class1.cs
rename to Software/E_Libra/EntitiesLayer/F16/GPTChoices.cs
index adbcc73..24c0189 100644
--- a/Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/Class1.cs	
+++ b/Software/E_Libra/EntitiesLayer/F16/GPTChoices.cs
@@ -4,9 +4,10 @@
 using System.Text;
 using System.Threading.Tasks;
 
-namespace IntegrationTesting.Nove_funkcionalnosti.F16
+namespace EntitiesLayer.F16
 {
-    internal class Class1
+    public class GPTChoices
     {
+        public GPTMessage message { get; set; }
     }
 }
diff --git a/Software/E_Libra/EntitiesLayer/F16/GPTResponse.cs b/Software/E_Libra/EntitiesLayer/F16/GPTResponse.cs
index e5dedd4..73bd45c 100644
--- a/Software/E_Libra/EntitiesLayer/F16/GPTResponse.cs
+++ b/Software/E_Libra/EntitiesLayer/F16/GPTResponse.cs
@@ -8,5 +8,6 @@ namespace EntitiesLayer.F16
 {
     public class GPTResponse
     {
+        public List<GPTChoices> choices { get; set; }
     }
 }
diff --git a/Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/GPTService_integrationTest.cs b/Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/GPTService_integrationTest.cs
new file mode 100644
index 0000000..78bd5b2
--- /dev/null
+++ b/Software/E_Libra/IntegrationTesting/Nove funkcionalnosti/F16/GPTService_integrationTest.cs	
@@ -0,0 +1,77 @@
+using BussinessLogicLayer.F16;
+using DataAccessLayer.F16;
+using EntitiesLayer.F16;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace IntegrationTesting.Nove_funkcionalnosti.F16
+{
+    //David Matijanić
+    public class GPTService_integrationTest
+    {
+        private GPTService gptService { get; set; }
+
+        public GPTService_integrationTest()
+        {
+            gptService = new GPTService(new GPTRequestSender("API-key"));
+        }
+
+        [Fact]
+        public async Task SendSystemMessage_MessageSent_ShouldReturnString()
+        {
+            //Arrange
+            string message = "Korisnik te pitao za pomoć oko knjige.";
+
+            //Act
+            var result = await gptService.SendSystemMessage(message);
+
+            //Assert
+            Assert.IsType<string>(result);
+        }
+
+        [Fact]
+        public async Task SendSystemMessage_SystemMessageSetAndMessageSent_ShouldReturnString()
+        {
+            //Arrange
+            string message = "Korisnik te pitao za pomoć oko knjige.";
+            gptService.SetSystemMessage("Ti si pomoćnik u knjižnici.");
+
+            //Act
+            var result = await gptService.SendSystemMessage(message);
+
+            //Assert
+            Assert.IsType<string>(result);
+        }
+
+        [Fact]
+        public async Task SendUserMessage_MessageSent_ShouldReturnString()
+        {
+            //Arrange
+            string message = "Korisnik te pitao za pomoć oko knjige.";
+
+            //Act
+            var result = await gptService.SendUserMessage(message);
+
+            //Assert
+            Assert.IsType<string>(result);
+        }
+
+        [Fact]
+        public async Task SendUserMessage_SystemMessageSetAndMessageSent_ShouldReturnString()
+        {
+            //Arrange
+            string message = "Korisnik te pitao za pomoć oko knjige.";
+            gptService.SetSystemMessage("Ti si pomoćnik u knjižnici.");
+
+            //Act
+            var result = await gptService.SendUserMessage(message);
+
+            //Assert
+            Assert.IsType<string>(result);
+        }
+    }
+}