diff --git a/src/FlareSolverrSharp/ClearanceHandler.cs b/src/FlareSolverrSharp/ClearanceHandler.cs
index e166383..a1e37f8 100644
--- a/src/FlareSolverrSharp/ClearanceHandler.cs
+++ b/src/FlareSolverrSharp/ClearanceHandler.cs
@@ -20,6 +20,7 @@ public class ClearanceHandler : DelegatingHandler
     {
         private readonly HttpClient _client;
         private readonly string _flareSolverrApiUrl;
+        private readonly IFlaresolverrResponseStorage _responseStorage;
         private FlareSolverr _flareSolverr;
         private string _userAgent;
 
@@ -42,6 +43,17 @@ public class ClearanceHandler : DelegatingHandler
         /// <param name="flareSolverrApiUrl">FlareSolverr API URL. If null or empty it will detect the challenges, but
         /// they will not be solved. Example: "http://localhost:8191/"</param>
         public ClearanceHandler(string flareSolverrApiUrl)
+            : this(flareSolverrApiUrl, new DefaultFlaresolverrResponseStorage())
+        {
+        }
+
+        /// <summary>
+        /// Creates a new instance of the <see cref="ClearanceHandler"/>.
+        /// </summary>
+        /// <param name="flareSolverrApiUrl">FlareSolverr API URL. If null or empty it will detect the challenges, but
+        /// they will not be solved. Example: "http://localhost:8191/"</param>
+        /// <param name="responseStorage">Storage to persist challenge responses.</param>
+        public ClearanceHandler(string flareSolverrApiUrl, IFlaresolverrResponseStorage responseStorage)
             : base(new HttpClientHandler())
         {
             // Validate URI
@@ -50,6 +62,7 @@ public ClearanceHandler(string flareSolverrApiUrl)
                 throw new FlareSolverrException("FlareSolverr URL is malformed: " + flareSolverrApiUrl);
 
             _flareSolverrApiUrl = flareSolverrApiUrl;
+            _responseStorage = responseStorage;
 
             _client = new HttpClient(new HttpClientHandler
             {
@@ -84,36 +97,64 @@ protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage
             var response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
             // Detect if there is a challenge in the response
-            if (ChallengeDetector.IsClearanceRequired(response))
+            if (!ChallengeDetector.IsClearanceRequired(response))
             {
-                if (_flareSolverr == null)
-                    throw new FlareSolverrException("Challenge detected but FlareSolverr is not configured");
+                return response;
+            }
 
-                // Resolve the challenge using FlareSolverr API
-                var flareSolverrResponse = await _flareSolverr.Solve(request);
+            if (_flareSolverr == null)
+                throw new FlareSolverrException("Challenge detected but FlareSolverr is not configured");
+            
+            // Check if saved response exists.
+            var flareSolverrResponse = await _responseStorage.LoadAsync();
 
-                // Save the FlareSolverr User-Agent for the following requests
-                var flareSolverUserAgent = flareSolverrResponse.Solution.UserAgent;
-                if (flareSolverUserAgent != null && !flareSolverUserAgent.Equals(request.Headers.UserAgent.ToString()))
+            if (flareSolverrResponse != null)
+            {
+                // Set user agent
+                if (flareSolverrResponse.Solution.UserAgent != null &&
+                    !flareSolverrResponse.Solution.UserAgent.Equals(request.Headers.UserAgent.ToString()))
                 {
-                    _userAgent = flareSolverUserAgent;
-
-                    // Set the User-Agent if required
+                    _userAgent = flareSolverrResponse.Solution.UserAgent;
                     SetUserAgentHeader(request);
                 }
 
-                // Change the cookies in the original request with the cookies provided by FlareSolverr
+                // Retry request with saved response
                 InjectCookies(request, flareSolverrResponse);
                 response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
-                // Detect if there is a challenge in the response
-                if (ChallengeDetector.IsClearanceRequired(response))
-                    throw new FlareSolverrException("The cookies provided by FlareSolverr are not valid");
+                if (!ChallengeDetector.IsClearanceRequired(response))
+                {
+                    // Success with saved response.
+                    InjectSetCookieHeader(response, flareSolverrResponse);
+                    return response;
+                }
+            }
+
+            // Resolve the challenge using FlareSolverr API
+            flareSolverrResponse = await _flareSolverr.Solve(request);
+
+            // Save the FlareSolverr User-Agent for the following requests
+            var flareSolverUserAgent = flareSolverrResponse.Solution.UserAgent;
+            if (flareSolverUserAgent != null && !flareSolverUserAgent.Equals(request.Headers.UserAgent.ToString()))
+            {
+                _userAgent = flareSolverUserAgent;
 
-                // Add the "Set-Cookie" header in the response with the cookies provided by FlareSolverr
-                InjectSetCookieHeader(response, flareSolverrResponse);
+                // Set the User-Agent if required
+                SetUserAgentHeader(request);
             }
 
+            // Change the cookies in the original request with the cookies provided by FlareSolverr
+            InjectCookies(request, flareSolverrResponse);
+            response = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
+
+            // Detect if there is a challenge in the response
+            if (ChallengeDetector.IsClearanceRequired(response))
+                throw new FlareSolverrException("The cookies provided by FlareSolverr are not valid");
+
+            // Add the "Set-Cookie" header in the response with the cookies provided by FlareSolverr
+            InjectSetCookieHeader(response, flareSolverrResponse);
+            await _responseStorage.SaveAsync(flareSolverrResponse);
+
             return response;
         }
 
diff --git a/src/FlareSolverrSharp/FlareSolverrSharp.csproj b/src/FlareSolverrSharp/FlareSolverrSharp.csproj
index c51af3f..8f98d59 100644
--- a/src/FlareSolverrSharp/FlareSolverrSharp.csproj
+++ b/src/FlareSolverrSharp/FlareSolverrSharp.csproj
@@ -1,7 +1,9 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>netstandard1.3</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <LangVersion>latest</LangVersion>
+    <Nullable>enable</Nullable>
     <PackageId>FlareSolverrSharp</PackageId>
     <RootNamespace>FlareSolverrSharp</RootNamespace>
     <Version>3.0.5</Version>
@@ -16,7 +18,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Newtonsoft.Json" Version="13.0.2" />
+    <PackageReference Include="System.Text.Json" Version="7.0.3" />
   </ItemGroup>
 
 </Project>
diff --git a/src/FlareSolverrSharp/FlaresolverrResponseStorage.cs b/src/FlareSolverrSharp/FlaresolverrResponseStorage.cs
new file mode 100644
index 0000000..1850222
--- /dev/null
+++ b/src/FlareSolverrSharp/FlaresolverrResponseStorage.cs
@@ -0,0 +1,24 @@
+using System.Threading.Tasks;
+using FlareSolverrSharp.Types;
+
+namespace FlareSolverrSharp
+{
+    public interface IFlaresolverrResponseStorage
+    {
+        Task SaveAsync(FlareSolverrResponse result);
+        Task<FlareSolverrResponse?> LoadAsync();
+    }
+
+    public class DefaultFlaresolverrResponseStorage : IFlaresolverrResponseStorage
+    {
+        public Task<FlareSolverrResponse?> LoadAsync()
+        {
+            return Task.FromResult<FlareSolverrResponse?>(null);
+        }
+
+        public Task SaveAsync(FlareSolverrResponse result)
+        {
+            return Task.CompletedTask;
+        }
+    }
+}
diff --git a/src/FlareSolverrSharp/Solvers/FlareSolverr.cs b/src/FlareSolverrSharp/Solvers/FlareSolverr.cs
index f4e6628..3716ecb 100644
--- a/src/FlareSolverrSharp/Solvers/FlareSolverr.cs
+++ b/src/FlareSolverrSharp/Solvers/FlareSolverr.cs
@@ -2,11 +2,11 @@
 using System.Net;
 using System.Net.Http;
 using System.Text;
+using System.Text.Json;
 using System.Threading.Tasks;
 using FlareSolverrSharp.Exceptions;
 using FlareSolverrSharp.Types;
 using FlareSolverrSharp.Utilities;
-using Newtonsoft.Json;
 
 namespace FlareSolverrSharp.Solvers
 {
@@ -102,7 +102,9 @@ await Locker.LockAsync(async () =>
                 var resContent = await response.Content.ReadAsStringAsync();
                 try
                 {
-                    result = JsonConvert.DeserializeObject<FlareSolverrResponse>(resContent);
+                    result = JsonSerializer.Deserialize(
+                        resContent,
+                        FlareSolverrContext.Default.FlareSolverrResponse);
                 }
                 catch (Exception)
                 {
@@ -160,10 +162,9 @@ private FlareSolverrRequestProxy GetProxy()
 
         private HttpContent GetSolverRequestContent(FlareSolverrRequest request)
         {
-            var payload = JsonConvert.SerializeObject(request, new JsonSerializerSettings
-            {
-                NullValueHandling = NullValueHandling.Ignore
-            });
+            var payload = JsonSerializer.Serialize(
+                request,
+                FlareSolverrContext.Default.FlareSolverrRequest);
             HttpContent content = new StringContent(payload, Encoding.UTF8, "application/json");
             return content;
         }
diff --git a/src/FlareSolverrSharp/Solvers/FlareSolverrContext.cs b/src/FlareSolverrSharp/Solvers/FlareSolverrContext.cs
new file mode 100644
index 0000000..d798168
--- /dev/null
+++ b/src/FlareSolverrSharp/Solvers/FlareSolverrContext.cs
@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+using FlareSolverrSharp.Types;
+
+namespace FlareSolverrSharp.Solvers
+{
+    [JsonSerializable(typeof(FlareSolverrRequest))]
+    [JsonSerializable(typeof(FlareSolverrResponse))]
+    [JsonSourceGenerationOptions(DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull)]
+    public partial class FlareSolverrContext : JsonSerializerContext
+    {
+    }
+}
\ No newline at end of file
diff --git a/src/FlareSolverrSharp/Types/FlareSolverrRequest.cs b/src/FlareSolverrSharp/Types/FlareSolverrRequest.cs
index 49bd18b..a292382 100644
--- a/src/FlareSolverrSharp/Types/FlareSolverrRequest.cs
+++ b/src/FlareSolverrSharp/Types/FlareSolverrRequest.cs
@@ -1,19 +1,21 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 namespace FlareSolverrSharp.Types
 {
+    [JsonDerivedType(typeof(FlareSolverrRequestGet))]
+    [JsonDerivedType(typeof(FlareSolverrRequestPost))]
     public class FlareSolverrRequest
     {
-        [JsonProperty("cmd")]
-        public string Cmd;
+        [JsonPropertyName("cmd")]
+        public string Cmd { get; set; }
 
-        [JsonProperty("url")]
-        public string Url;
+        [JsonPropertyName("url")]
+        public string Url { get; set; }
 
-        [JsonProperty("session")]
-        public string Session;
+        [JsonPropertyName("session")]
+        public string Session { get; set; }
 
-        [JsonProperty("proxy")]
-        public FlareSolverrRequestProxy Proxy;
+        [JsonPropertyName("proxy")]
+        public FlareSolverrRequestProxy Proxy { get; set; }
     }
 }
diff --git a/src/FlareSolverrSharp/Types/FlareSolverrRequestGet.cs b/src/FlareSolverrSharp/Types/FlareSolverrRequestGet.cs
index 41b520b..b73d33c 100644
--- a/src/FlareSolverrSharp/Types/FlareSolverrRequestGet.cs
+++ b/src/FlareSolverrSharp/Types/FlareSolverrRequestGet.cs
@@ -1,10 +1,10 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 namespace FlareSolverrSharp.Types
 {
     public class FlareSolverrRequestGet : FlareSolverrRequest
     {
-        [JsonProperty("maxTimeout")]
-        public int MaxTimeout;
+        [JsonPropertyName("maxTimeout")]
+        public int MaxTimeout  { get; set; }
     }
 }
\ No newline at end of file
diff --git a/src/FlareSolverrSharp/Types/FlareSolverrRequestPost.cs b/src/FlareSolverrSharp/Types/FlareSolverrRequestPost.cs
index 932c5f1..b64cd20 100644
--- a/src/FlareSolverrSharp/Types/FlareSolverrRequestPost.cs
+++ b/src/FlareSolverrSharp/Types/FlareSolverrRequestPost.cs
@@ -1,13 +1,13 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 namespace FlareSolverrSharp.Types
 {
     public class FlareSolverrRequestPost : FlareSolverrRequest
     {
-        [JsonProperty("postData")]
-        public string PostData;
+        [JsonPropertyName("postData")]
+        public string PostData { get; set; }
 
-        [JsonProperty("maxTimeout")]
-        public int MaxTimeout;
+        [JsonPropertyName("maxTimeout")]
+        public int MaxTimeout { get; set; }
     }
 }
\ No newline at end of file
diff --git a/src/FlareSolverrSharp/Types/FlareSolverrRequestProxy.cs b/src/FlareSolverrSharp/Types/FlareSolverrRequestProxy.cs
index d8e3135..8dde077 100644
--- a/src/FlareSolverrSharp/Types/FlareSolverrRequestProxy.cs
+++ b/src/FlareSolverrSharp/Types/FlareSolverrRequestProxy.cs
@@ -1,10 +1,10 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 namespace FlareSolverrSharp.Types
 {
     public class FlareSolverrRequestProxy
     {
-        [JsonProperty("url")]
-        public string Url;
+        [JsonPropertyName("url")]
+        public string Url  { get; set; }
     }
 }
diff --git a/src/FlareSolverrSharp/Types/FlareSolverrResponse.cs b/src/FlareSolverrSharp/Types/FlareSolverrResponse.cs
index e852ef7..8a2a3ce 100644
--- a/src/FlareSolverrSharp/Types/FlareSolverrResponse.cs
+++ b/src/FlareSolverrSharp/Types/FlareSolverrResponse.cs
@@ -1,4 +1,4 @@
-using Newtonsoft.Json;
+using System.Text.Json.Serialization;
 
 // ReSharper disable UnusedMember.Global
 // ReSharper disable UnassignedField.Global
@@ -7,38 +7,77 @@ namespace FlareSolverrSharp.Types
 {
     public class FlareSolverrResponse
     {
-        public string Status;
-        public string Message;
-        public long StartTimestamp;
-        public long EndTimestamp;
-        public string Version;
-        public Solution Solution;
-        public string Session;
-        public string[] Sessions;
+        [JsonPropertyName("status")]
+        public string Status { get; set; }
+
+        [JsonPropertyName("message")]
+        public string Message { get; set; }
+        
+        [JsonPropertyName("startTimestamp")]
+        public long StartTimestamp { get; set; }
+
+        [JsonPropertyName("endTimestamp")]
+        public long EndTimestamp { get; set; }
+
+        [JsonPropertyName("version")]
+        public string Version { get; set; }
+
+        [JsonPropertyName("solution")]
+        public Solution Solution { get; set; }
     }
 
     public class Solution
     {
-        public string Url;
-        public string Status;
-        public Headers Headers;
-        public string Response;
-        public Cookie[] Cookies;
-        public string UserAgent;
+        [JsonPropertyName("url")]
+        public string Url { get; set; }
+
+        [JsonPropertyName("status")]
+        public int Status { get; set; }
+
+        [JsonPropertyName("headers")]
+        public Headers Headers { get; set; }
+
+        [JsonPropertyName("response")]
+        public string Response { get; set; }
+
+        [JsonPropertyName("cookies")]
+        public Cookie[] Cookies { get; set; }
+
+        [JsonPropertyName("userAgent")]
+        public string UserAgent { get; set; }
     }
 
     public class Cookie
     {
-        public string Name;
-        public string Value;
-        public string Domain;
-        public string Path;
-        public double Expires;
-        public int Size;
-        public bool HttpOnly;
-        public bool Secure;
-        public bool Session;
-        public string SameSite;
+        [JsonPropertyName("name")]
+        public string Name { get; set; }
+
+        [JsonPropertyName("value")]
+        public string Value { get; set; }
+
+        [JsonPropertyName("domain")]
+        public string Domain { get; set; }
+        
+        [JsonPropertyName("path")]
+        public string Path { get; set; }
+
+        [JsonPropertyName("expiry")]
+        public double Expires { get; set; }
+
+        [JsonPropertyName("size")]
+        public int Size { get; set; }
+        
+        [JsonPropertyName("httpOnly")]
+        public bool HttpOnly { get; set; }
+
+        [JsonPropertyName("secure")]
+        public bool Secure { get; set; }
+
+        [JsonPropertyName("session")]
+        public bool Session { get; set; }
+
+        [JsonPropertyName("sameSite")]
+        public string SameSite { get; set; }
 
         public string ToHeaderValue() => $"{Name}={Value}";
         public System.Net.Cookie ToCookieObj() => new System.Net.Cookie(Name, Value);
@@ -47,9 +86,13 @@ public class Cookie
 
     public class Headers
     {
-        public string Status;
-        public string Date;
-        [JsonProperty(PropertyName = "content-type")]
-        public string ContentType;
+        [JsonPropertyName("status")]
+        public string Status { get; set; }
+        
+        [JsonPropertyName("date")]
+        public string Date { get; set; }
+
+        [JsonPropertyName("content-type")]
+        public string ContentType { get; set; }
     }
 }
\ No newline at end of file