diff --git a/Package.resolved b/Package.resolved
index bc7ce25..5d87b5e 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -1,4 +1,5 @@
 {
+  "originHash" : "eded34b26489ba15446e8f9724a747ccb282c199510abfd2c0945b326d7932a4",
   "pins" : [
     {
       "identity" : "alamofire",
@@ -10,5 +11,5 @@
       }
     }
   ],
-  "version" : 2
+  "version" : 3
 }
diff --git a/Sources/ipinfoKit/API/API.swift b/Sources/ipinfoKit/API/API.swift
index 07058fa..9fa135e 100644
--- a/Sources/ipinfoKit/API/API.swift
+++ b/Sources/ipinfoKit/API/API.swift
@@ -37,7 +37,7 @@ extension Service.Router {
 // MARK: - Service
 
 @MainActor
-class Service {
+public class Service {
     
     // MARK: Lifecycle
     
@@ -45,7 +45,7 @@ class Service {
     
     // MARK: Internal
     
-    static let shared = Service()
+    public static let shared = Service()
     
     var ipInfoURL = "https://ipinfo.io"
     let headers: HTTPHeaders = [
@@ -53,6 +53,9 @@ class Service {
         "User-Agent": "IPinfoClient/Swift/\(Constants.SDK_VERSION)",
     ]
     
+    /// Custom session for testing. When nil, uses default AF session.
+    public var session: Session?
+    
     @MainActor
     func requestAPI(
         URL: Service.Router,
@@ -60,7 +63,8 @@ class Service {
         params: Parameters? = nil,
         completion: @escaping (_ status: Response,_ data: Data,_ msg: String) -> Void) {
             
-            AF.request(URL.endPoint , method: method, parameters: params , encoding: JSONEncoding.default, headers: headers)
+            let requestSession = session ?? AF
+            requestSession.request(URL.endPoint , method: method, parameters: params , encoding: JSONEncoding.default, headers: headers)
                 .response { response in
                     DispatchQueue.main.async {
                         switch response.result {
diff --git a/Tests/ipinfoKitTests/ResproxyTests.swift b/Tests/ipinfoKitTests/ResproxyTests.swift
index b4c9ba6..6b53422 100644
--- a/Tests/ipinfoKitTests/ResproxyTests.swift
+++ b/Tests/ipinfoKitTests/ResproxyTests.swift
@@ -1,10 +1,53 @@
+import Alamofire
 import Foundation
 import Testing
 import ipinfoKit
 
+/// Custom URLProtocol that only mocks specific URLs for resproxy tests
+private class ResproxyMockURLProtocol: URLProtocol {
+    nonisolated(unsafe) static var mockResponses: [String: Data] = [:]
+
+    override class func canInit(with request: URLRequest) -> Bool {
+        guard let url = request.url?.absoluteString else { return false }
+        return mockResponses.keys.contains(url)
+    }
+
+    override class func canonicalRequest(for request: URLRequest) -> URLRequest {
+        return request
+    }
+
+    override func startLoading() {
+        guard let url = request.url?.absoluteString,
+              let data = ResproxyMockURLProtocol.mockResponses[url] else {
+            client?.urlProtocol(self, didFailWithError: NSError(domain: "ResproxyMockURLProtocol", code: 404))
+            return
+        }
+
+        let response = HTTPURLResponse(url: request.url!, statusCode: 200, httpVersion: "HTTP/1.1", headerFields: ["Content-Type": "application/json"])!
+        client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
+        client?.urlProtocol(self, didLoad: data)
+        client?.urlProtocolDidFinishLoading(self)
+    }
+
+    override func stopLoading() {}
+}
+
 @MainActor
 struct ResproxyTests {
+
     @Test func resproxyTest() async throws {
+        // Set up mock response
+        let mockData = """
+            {"ip":"175.107.211.204","last_seen":"2025-01-20","percent_days_seen":0.85,"service":"example_service"}
+            """.data(using: .utf8)!
+        ResproxyMockURLProtocol.mockResponses["https://ipinfo.io/resproxy/175.107.211.204"] = mockData
+
+        // Configure mock session for this test
+        let configuration = URLSessionConfiguration.ephemeral
+        configuration.protocolClasses = [ResproxyMockURLProtocol.self]
+        let mockSession = Session(configuration: configuration)
+        Service.shared.session = mockSession
+
         let response = try await withCheckedThrowingContinuation { continuation in
             IPINFO.shared.getResproxy(ip: "175.107.211.204") { status, response, msg in
                 switch status {
@@ -26,13 +69,26 @@ struct ResproxyTests {
             }
         }
 
+        Service.shared.session = nil
+        ResproxyMockURLProtocol.mockResponses.removeAll()
+
         #expect(response.ip == "175.107.211.204")
-        #expect(response.lastSeen != nil)
-        #expect(response.percentDaysSeen != nil)
-        #expect(response.service != nil)
+        #expect(response.lastSeen == "2025-01-20")
+        #expect(response.percentDaysSeen == 0.85)
+        #expect(response.service == "example_service")
     }
 
     @Test func resproxyEmptyTest() async throws {
+        // Set up mock response for empty result
+        let mockData = "{}".data(using: .utf8)!
+        ResproxyMockURLProtocol.mockResponses["https://ipinfo.io/resproxy/8.8.8.8"] = mockData
+
+        // Configure mock session for this test
+        let configuration = URLSessionConfiguration.ephemeral
+        configuration.protocolClasses = [ResproxyMockURLProtocol.self]
+        let mockSession = Session(configuration: configuration)
+        Service.shared.session = mockSession
+
         let response = try await withCheckedThrowingContinuation { continuation in
             IPINFO.shared.getResproxy(ip: "8.8.8.8") { status, response, msg in
                 switch status {
@@ -54,6 +110,9 @@ struct ResproxyTests {
             }
         }
 
+        Service.shared.session = nil
+        ResproxyMockURLProtocol.mockResponses.removeAll()
+
         #expect(response.ip == nil)
         #expect(response.lastSeen == nil)
         #expect(response.percentDaysSeen == nil)