diff --git a/CHANGELOG.md b/CHANGELOG.md
index cfaae45..c3884f1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
+# 2.8.1
+
+- Feature: sitekey ("apiKey") syntax validation
+
 # 2.8.0
 
-- Feature: passive site key ([#152](https://github.com/hCaptcha/HCaptcha-ios-sdk/issues/152))
+- Feature: passive sitekey ([#152](https://github.com/hCaptcha/HCaptcha-ios-sdk/issues/152))
 - Feature: upgrade Xcode to 15. NOTE: this also increases the minimum supported iOS version to 12. ([#134](https://github.com/hCaptcha/HCaptcha-ios-sdk/issues/134))
 
 
diff --git a/Example/HCaptcha_Tests/Core/HCaptchaWebViewManager__Tests.swift b/Example/HCaptcha_Tests/Core/HCaptchaWebViewManager__Tests.swift
index 7be6707..a1689e8 100644
--- a/Example/HCaptcha_Tests/Core/HCaptchaWebViewManager__Tests.swift
+++ b/Example/HCaptcha_Tests/Core/HCaptchaWebViewManager__Tests.swift
@@ -21,7 +21,7 @@ class HCaptchaWebViewManager__Tests: XCTestCase {
         super.setUp()
 
         presenterView = UIApplication.shared.keyWindow?.rootViewController?.view
-        apiKey = String(arc4random())
+        apiKey = UUID().uuidString
     }
 
     override func tearDown() {
diff --git a/Example/HCaptcha_Tests/Core/HCaptcha__Config__Tests.swift b/Example/HCaptcha_Tests/Core/HCaptcha__Config__Tests.swift
index 7e3ed0b..44993ec 100644
--- a/Example/HCaptcha_Tests/Core/HCaptcha__Config__Tests.swift
+++ b/Example/HCaptcha_Tests/Core/HCaptcha__Config__Tests.swift
@@ -10,15 +10,17 @@
 import XCTest
 
 class HCaptcha__Config__Tests: XCTestCase {
+    private static let sApiKey = UUID().uuidString
     private let expected = "https://hcaptcha.com/1/api.js?onload=onloadCallback&render=explicit&recaptchacompat=off"
-        + "&host=some-api-key.ios-sdk.hcaptcha.com&sentry=false&endpoint=https%3A%2F%2Fapi.hcaptcha.com"
+        + "&host=\(sApiKey).ios-sdk.hcaptcha.com&sentry=false&endpoint=https%3A%2F%2Fapi.hcaptcha.com"
         + "&assethost=https%3A%2F%2Fnewassets.hcaptcha.com&imghost=https%3A%2F%2Fimgs.hcaptcha.com"
         + "&reportapi=https%3A%2F%2Faccounts.hcaptcha.com"
+    private let apiKey = sApiKey
 
     func test__Base_URL() {
         // Ensures baseURL failure when nil
         do {
-            _ = try HCaptchaConfig(apiKey: "", infoPlistKey: nil, baseURL: nil, infoPlistURL: nil)
+            _ = try HCaptchaConfig(apiKey: apiKey, infoPlistKey: nil, baseURL: nil, infoPlistURL: nil)
             XCTFail("Should have failed")
         } catch let e as HCaptchaError {
             print(e)
@@ -29,24 +31,24 @@ class HCaptcha__Config__Tests: XCTestCase {
 
         // Ensures plist url if nil key
         let plistURL = URL(string: "https://bar")!
-        let config1 = try? HCaptchaConfig(apiKey: "", infoPlistKey: nil, baseURL: nil, infoPlistURL: plistURL)
+        let config1 = try? HCaptchaConfig(apiKey: apiKey, infoPlistKey: nil, baseURL: nil, infoPlistURL: plistURL)
         XCTAssertEqual(config1?.baseURL, plistURL)
 
         // Ensures preference of given url over plist entry
         let url = URL(string: "ftp://foo")!
-        let config2 = try? HCaptchaConfig(apiKey: "", infoPlistKey: nil, baseURL: url, infoPlistURL: plistURL)
+        let config2 = try? HCaptchaConfig(apiKey: apiKey, infoPlistKey: nil, baseURL: url, infoPlistURL: plistURL)
         XCTAssertEqual(config2?.baseURL, url)
     }
 
     func test__Base_URL_Without_Scheme() {
         // Ignores URL with scheme
         let goodURL = URL(string: "https://foo.bar")!
-        let config0 = try? HCaptchaConfig(apiKey: "", infoPlistKey: nil, baseURL: goodURL, infoPlistURL: nil)
+        let config0 = try? HCaptchaConfig(apiKey: apiKey, infoPlistKey: nil, baseURL: goodURL, infoPlistURL: nil)
         XCTAssertEqual(config0?.baseURL, goodURL)
 
         // Fixes URL without scheme
         let badURL = URL(string: "foo")!
-        let config = try? HCaptchaConfig(apiKey: "", infoPlistKey: nil, baseURL: badURL, infoPlistURL: nil)
+        let config = try? HCaptchaConfig(apiKey: apiKey, infoPlistKey: nil, baseURL: badURL, infoPlistURL: nil)
         XCTAssertEqual(config?.baseURL.absoluteString, "http://" + badURL.absoluteString)
     }
 
@@ -63,7 +65,7 @@ class HCaptcha__Config__Tests: XCTestCase {
         }
 
         // Ensures plist key if nil key
-        let plistKey = "bar"
+        let plistKey = UUID().uuidString
         let config1 = try? HCaptchaConfig(
             apiKey: nil,
             infoPlistKey: plistKey,
@@ -73,35 +75,34 @@ class HCaptcha__Config__Tests: XCTestCase {
         XCTAssertEqual(config1?.apiKey, plistKey)
 
         // Ensures preference of given key over plist entry
-        let key = "foo"
         let config2 = try? HCaptchaConfig(
-            apiKey: key,
+            apiKey: apiKey,
             infoPlistKey: plistKey,
             baseURL: URL(string: "foo"),
             infoPlistURL: nil
         )
-        XCTAssertEqual(config2?.apiKey, key)
+        XCTAssertEqual(config2?.apiKey, apiKey)
     }
 
     func test__Locale__Nil() {
-        let config = try? HCaptchaConfig()
+        let config = try? HCaptchaConfig(apiKey: apiKey)
         let actual = config?.actualEndpoint.absoluteString
         XCTAssertEqual(actual, expected)
     }
 
     func test__Locale__Valid() {
         let locale = Locale(identifier: "pt-BR")
-        let config = try? HCaptchaConfig(locale: locale)
+        let config = try? HCaptchaConfig(apiKey: apiKey, locale: locale)
         let actual = config?.actualEndpoint.absoluteString
         XCTAssertEqual(actual, "\(expected)&hl=\(locale.identifier)")
     }
 
     func test__Custom__Host() {
         let host = "custom-host"
-        let config = try? HCaptchaConfig(host: host)
+        let config = try? HCaptchaConfig(apiKey: apiKey, host: host)
         let actual = config?.actualEndpoint.absoluteString
         XCTAssertEqual(actual, expected.replacingOccurrences(
-            of: "some-api-key.ios-sdk.hcaptcha.com",
+            of: "\(apiKey).ios-sdk.hcaptcha.com",
             with: host))
     }
 
@@ -117,7 +118,7 @@ class HCaptcha__Config__Tests: XCTestCase {
             }
           }
         """
-        let config = try? HCaptchaConfig(customTheme: customTheme)
+        let config = try? HCaptchaConfig(apiKey: apiKey, customTheme: customTheme)
         let actual = config?.actualEndpoint.absoluteString
         XCTAssertEqual(actual, expected + "&custom=true")
     }
diff --git a/Example/HCaptcha_Tests/Helpers/HCaptchaConfig+Helpers.swift b/Example/HCaptcha_Tests/Helpers/HCaptchaConfig+Helpers.swift
index f0a43f9..074e646 100644
--- a/Example/HCaptcha_Tests/Helpers/HCaptchaConfig+Helpers.swift
+++ b/Example/HCaptcha_Tests/Helpers/HCaptchaConfig+Helpers.swift
@@ -11,7 +11,7 @@ import Foundation
 
 extension HCaptchaConfig {
     init(html: String = HCaptchaHtml.template,
-         apiKey: String? = String(arc4random()),
+         apiKey: String? = UUID().uuidString,
          passiveApiKey: Bool = false,
          infoPlistKey: String? = "api-key",
          baseURL: URL? = URL(string: "http://localhost")!,
@@ -46,7 +46,7 @@ extension HCaptchaConfig {
                       locale: locale)
     }
 
-    init(apiKey: String = "some-api-key",
+    init(apiKey: String = UUID().uuidString,
          host: String? = nil,
          customTheme: String? = nil,
          locale: Locale? = nil) throws {
diff --git a/Example/HCaptcha_Tests/Helpers/HCaptchaWebViewManager+Helpers.swift b/Example/HCaptcha_Tests/Helpers/HCaptchaWebViewManager+Helpers.swift
index 1990cf4..2c7d730 100644
--- a/Example/HCaptcha_Tests/Helpers/HCaptchaWebViewManager+Helpers.swift
+++ b/Example/HCaptcha_Tests/Helpers/HCaptchaWebViewManager+Helpers.swift
@@ -37,7 +37,7 @@ extension HCaptchaWebViewManager {
 
         self.init(
             html: html,
-            apiKey: apiKey ?? "api-key",
+            apiKey: apiKey ?? UUID().uuidString,
             passiveApiKey: passiveApiKey,
             endpoint: endpoint ?? URL(string: "https://api.hcaptcha.com")!,
             size: size,
diff --git a/Example/HCaptcha_Tests/RxSwift/HCaptcha+Rx__Tests.swift b/Example/HCaptcha_Tests/RxSwift/HCaptcha+Rx__Tests.swift
index 48bd237..e6c8bce 100644
--- a/Example/HCaptcha_Tests/RxSwift/HCaptcha+Rx__Tests.swift
+++ b/Example/HCaptcha_Tests/RxSwift/HCaptcha+Rx__Tests.swift
@@ -23,7 +23,7 @@ class HCaptcha_Rx__Tests: XCTestCase {
         super.setUp()
 
         presenterView = UIApplication.shared.keyWindow!
-        apiKey = String(arc4random())
+        apiKey = UUID().uuidString
     }
 
     override func tearDown() {
diff --git a/Example/Podfile.lock b/Example/Podfile.lock
index 8c7bbf7..d34ae1e 100644
--- a/Example/Podfile.lock
+++ b/Example/Podfile.lock
@@ -1,7 +1,7 @@
 PODS:
   - AppSwizzle (1.3.1)
-  - HCaptcha/Core (2.8.0)
-  - HCaptcha/RxSwift (2.8.0):
+  - HCaptcha/Core (2.8.1)
+  - HCaptcha/RxSwift (2.8.1):
     - HCaptcha/Core
     - RxSwift (~> 6.2.0)
   - RxBlocking (6.2.0):
@@ -37,7 +37,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   AppSwizzle: db36e436f56110d93e5ae0147683435df593cabc
-  HCaptcha: 062308169f5cbd964f2ae25954fb773d19e469ed
+  HCaptcha: 210d88f8b553a0b33e71f0d3cc2fb2a52b520575
   RxBlocking: 0b29f7d2079109a8de49c411381bed7c33ef1eeb
   RxCocoa: 4baf94bb35f2c0ab31bc0cb9f1900155f646ba42
   RxRelay: e72dbfd157807478401ef1982e1c61c945c94b2f
diff --git a/HCaptcha.podspec b/HCaptcha.podspec
index cc32c3c..e62158e 100644
--- a/HCaptcha.podspec
+++ b/HCaptcha.podspec
@@ -1,6 +1,6 @@
 Pod::Spec.new do |s|
   s.name             = 'HCaptcha'
-  s.version          = '2.8.0'
+  s.version          = '2.8.1'
   s.summary          = 'HCaptcha for iOS'
   s.swift_version    = '5.0'
   
diff --git a/HCaptcha/Classes/HCaptchaConfig.swift b/HCaptcha/Classes/HCaptchaConfig.swift
index f7f945e..3302abb 100644
--- a/HCaptcha/Classes/HCaptchaConfig.swift
+++ b/HCaptcha/Classes/HCaptchaConfig.swift
@@ -214,6 +214,10 @@ struct HCaptchaConfig: CustomDebugStringConvertible {
             throw HCaptchaError.baseURLNotFound
         }
 
+        guard UUID(uuidString: apiKey) != nil else {
+            throw HCaptchaError.apiKeyInvalid
+        }
+
         if let customTheme = customTheme {
             let validationJS: String = "(function() { return \(customTheme) })()"
             let context = JSContext()!
diff --git a/HCaptcha/Classes/HCaptchaError.swift b/HCaptcha/Classes/HCaptchaError.swift
index 3bcb6e6..d8ad2a9 100644
--- a/HCaptcha/Classes/HCaptchaError.swift
+++ b/HCaptcha/Classes/HCaptchaError.swift
@@ -44,6 +44,9 @@ public enum HCaptchaError: Error, CustomStringConvertible {
     /// Invalid custom theme passed
     case invalidCustomTheme
 
+    /// HCaptchaKey is invalid
+    case apiKeyInvalid
+
     public static func == (lhs: HCaptchaError, rhs: HCaptchaError) -> Bool {
         return lhs.description == rhs.description
     }
@@ -63,6 +66,9 @@ public enum HCaptchaError: Error, CustomStringConvertible {
         case .apiKeyNotFound:
             return "HCaptchaKey not provided"
 
+        case .apiKeyInvalid:
+            return "HCaptchaKey invalid"
+
         case .baseURLNotFound:
             return "HCaptchaDomain not provided"