diff --git a/RateLimiter.Tests/RateLimiter.Tests.csproj b/RateLimiter.Tests/RateLimiter.Tests.csproj
index 5cbfc4e8..ef10b84d 100644
--- a/RateLimiter.Tests/RateLimiter.Tests.csproj
+++ b/RateLimiter.Tests/RateLimiter.Tests.csproj
@@ -9,6 +9,7 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
+    <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="NUnit" Version="3.13.3" />
     <PackageReference Include="NUnit3TestAdapter" Version="4.4.2" />
   </ItemGroup>
diff --git a/RateLimiter.Tests/RateLimiterTest.cs b/RateLimiter.Tests/RateLimiterTest.cs
index 172d44a7..5c2a26fd 100644
--- a/RateLimiter.Tests/RateLimiterTest.cs
+++ b/RateLimiter.Tests/RateLimiterTest.cs
@@ -1,13 +1,222 @@
-using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Moq;
+using NUnit.Framework;
+using Microsoft.Extensions.Logging;
+using RateLimiter.Rules;
 
-namespace RateLimiter.Tests;
-
-[TestFixture]
-public class RateLimiterTest
+namespace RateLimiter.Tests
 {
-	[Test]
-	public void Example()
-	{
-		Assert.That(true, Is.True);
-	}
+    [TestFixture]
+    public class FixedWindowRuleTests
+    {
+        [Test]
+        public void IsAllowed_WithinLimit_ReturnsTrue()
+        {
+            var rule = new FixedWindowRule(2, TimeSpan.FromMinutes(1));
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+
+        [Test]
+        public void IsAllowed_ExceedsLimit_ReturnsFalse()
+        {
+            var rule = new FixedWindowRule(2, TimeSpan.FromMinutes(1));
+            rule.IsAllowed("client1", "res1");
+            rule.IsAllowed("client1", "res1");
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.False);
+        }
+
+        [Test]
+        public void IsAllowed_AfterWindowReset_AllowsAgain()
+        {
+            var rule = new FixedWindowRule(1, TimeSpan.FromMilliseconds(50));
+            rule.IsAllowed("client1", "res1");
+            Thread.Sleep(100);
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+
+        [Test]
+        public void Cleanup_RemovesExpiredEntries()
+        {
+            var rule = new FixedWindowRule(1, TimeSpan.FromMilliseconds(50));
+            rule.IsAllowed("client1", "res1");
+            Thread.Sleep(100);
+            rule.Cleanup();
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+    }
+
+    [TestFixture]
+    public class SlidingWindowRuleTests
+    {
+        [Test]
+        public void IsAllowed_WithinLimit_ReturnsTrue()
+        {
+            var rule = new SlidingWindowRule(3, TimeSpan.FromMinutes(1));
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+
+        [Test]
+        public void IsAllowed_ExceedsLimit_ReturnsFalse()
+        {
+            var rule = new SlidingWindowRule(2, TimeSpan.FromMinutes(1));
+            rule.IsAllowed("client1", "res1");
+            rule.IsAllowed("client1", "res1");
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.False);
+        }
+
+        [Test]
+        public void IsAllowed_AfterSlidingWindow_AllowsAgain()
+        {
+            var rule = new SlidingWindowRule(2, TimeSpan.FromMilliseconds(100));
+            rule.IsAllowed("client1", "res1");
+            Thread.Sleep(50);
+            rule.IsAllowed("client1", "res1");
+            Thread.Sleep(60);
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+
+        [Test]
+        public void Cleanup_RemovesOldRequests()
+        {
+            var rule = new SlidingWindowRule(2, TimeSpan.FromMilliseconds(50));
+            rule.IsAllowed("client1", "res1");
+            Thread.Sleep(100);
+            rule.Cleanup();
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.True);
+        }
+    }
+
+    [TestFixture]
+    public class RegionalRuleTests
+    {
+        [Test]
+        public void IsAllowed_UsesCorrectRegionRule()
+        {
+            var usRule = new Mock<IRateLimitRule>();
+            usRule.Setup(r => r.IsAllowed("US-123", "res1")).Returns(true);
+
+            var euRule = new Mock<IRateLimitRule>();
+            euRule.Setup(r => r.IsAllowed("EU-456", "res1")).Returns(true);
+
+            var rule = new RegionalRule(new Dictionary<string, IRateLimitRule>
+            {
+                ["US"] = usRule.Object,
+                ["EU"] = euRule.Object
+            });
+
+            rule.IsAllowed("US-123", "res1");
+            usRule.Verify(r => r.IsAllowed("US-123", "res1"), Times.Once);
+
+            rule.IsAllowed("EU-456", "res1");
+            euRule.Verify(r => r.IsAllowed("EU-456", "res1"), Times.Once);
+        }
+
+        [Test]
+        public void IsAllowed_UnknownRegion_ReturnsFalse()
+        {
+            var rule = new RegionalRule(new Dictionary<string, IRateLimitRule>());
+            Assert.That(rule.IsAllowed("ASIA-789", "res1"), Is.False);
+        }
+    }
+
+    [TestFixture]
+    public class RateLimiterTests
+    {
+        private RateLimiter _rateLimiter;
+        private Mock<ILogger<RateLimiter>> _loggerMock;
+
+        [SetUp]
+        public void Setup()
+        {
+            _loggerMock = new Mock<ILogger<RateLimiter>>();
+            _rateLimiter = new RateLimiter(_loggerMock.Object);
+        }
+
+        [Test]
+        public void ResourceWithSingleFixedWindowRule_ShouldAllowWithinLimit()
+        {
+            var rule = new FixedWindowRule(3, TimeSpan.FromSeconds(10));
+            _rateLimiter.AddRule("resourceA", rule);
+
+            for (int i = 0; i < 3; i++)
+            {
+                Assert.IsTrue(_rateLimiter.IsRequestAllowed("client1", "resourceA"));
+            }
+            Assert.IsFalse(_rateLimiter.IsRequestAllowed("client1", "resourceA"));
+        }
+
+        [Test]
+        public void ResourceWithSingleSlidingWindowRule_ShouldAllowWithinLimit()
+        {
+            var rule = new SlidingWindowRule(2, TimeSpan.FromSeconds(5));
+            _rateLimiter.AddRule("resourceB", rule);
+
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("client2", "resourceB"));
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("client2", "resourceB"));
+            Assert.IsFalse(_rateLimiter.IsRequestAllowed("client2", "resourceB"));
+        }
+
+        [Test]
+        public void ResourceWithMultipleRules_ShouldDenyIfAnyRuleFails()
+        {
+            var fixedRule = new FixedWindowRule(2, TimeSpan.FromSeconds(10));
+            var slidingRule = new SlidingWindowRule(3, TimeSpan.FromSeconds(5));
+
+            _rateLimiter.AddRule("resourceC", fixedRule);
+            _rateLimiter.AddRule("resourceC", slidingRule);
+
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("client3", "resourceC"));
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("client3", "resourceC"));
+
+            Assert.IsFalse(_rateLimiter.IsRequestAllowed("client3", "resourceC"));
+
+            Thread.Sleep(10000);
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("client3", "resourceC"));
+        }
+
+        [Test]
+        public void RegionalRule_ShouldApplyCorrectRegionalLimits()
+        {
+            var regionalRule = new RegionalRule(new Dictionary<string, IRateLimitRule>
+            {
+                { "US", new FixedWindowRule(1, TimeSpan.FromSeconds(10)) },
+                { "ASIA", new SlidingWindowRule(2, TimeSpan.FromSeconds(5)) }
+            });
+
+            _rateLimiter.AddRule("resourceD", regionalRule);
+
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("US-client", "resourceD"));
+            Assert.IsFalse(_rateLimiter.IsRequestAllowed("US-client", "resourceD"));
+
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("ASIA-client", "resourceD"));
+            Assert.IsTrue(_rateLimiter.IsRequestAllowed("ASIA-client", "resourceD"));
+            Assert.IsFalse(_rateLimiter.IsRequestAllowed("ASIA-client", "resourceD"));
+        }
+    }
+
+    [TestFixture]
+    public class ConcurrencyTests
+    {
+        [Test]
+        public async Task FixedWindowRule_WithConcurrentRequests_EnforcesLimit()
+        {
+            var rule = new FixedWindowRule(10, TimeSpan.FromSeconds(1));
+            var tasks = new List<Task>();
+
+            for (int i = 0; i < 15; i++)
+            {
+                tasks.Add(Task.Run(() => rule.IsAllowed("client1", "res1")));
+            }
+
+            await Task.WhenAll(tasks);
+
+            Assert.That(rule.IsAllowed("client1", "res1"), Is.False);
+        }
+    }
 }
\ No newline at end of file
diff --git a/RateLimiter/RateLimiter.cs b/RateLimiter/RateLimiter.cs
new file mode 100644
index 00000000..575cc3fd
--- /dev/null
+++ b/RateLimiter/RateLimiter.cs
@@ -0,0 +1,50 @@
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using Microsoft.Extensions.Logging;
+using RateLimiter.Rules;
+
+namespace RateLimiter
+{
+    public class RateLimiter
+    {
+        private readonly ConcurrentDictionary<string, List<IRateLimitRule>> _resourceRules = new();
+        private readonly ILogger<RateLimiter> _logger;
+
+        public RateLimiter(ILogger<RateLimiter> logger)
+        {
+            _logger = logger;
+        }
+
+        public void AddRule(string resource, IRateLimitRule rule)
+        {
+            _resourceRules.AddOrUpdate(resource, _ => new List<IRateLimitRule> { rule }, (_, rules) => { rules.Add(rule); return rules; });
+        }
+
+        public bool IsRequestAllowed(string clientId, string resource)
+        {
+            if (!_resourceRules.TryGetValue(resource, out var rules))
+                return true;
+
+            foreach (var rule in rules)
+            {
+                if (!rule.IsAllowed(clientId, resource))
+                {
+                    _logger.LogWarning($"Request blocked: Client {clientId}, Resource {resource}");
+                    return false;
+                }
+            }
+            return true;
+        }
+
+        public void Cleanup()
+        {
+            foreach (var rules in _resourceRules.Values)
+            {
+                foreach (var rule in rules)
+                {
+                    rule.Cleanup();
+                }
+            }
+        }
+    }
+}
diff --git a/RateLimiter/RateLimiter.csproj b/RateLimiter/RateLimiter.csproj
index 19962f52..dac28970 100644
--- a/RateLimiter/RateLimiter.csproj
+++ b/RateLimiter/RateLimiter.csproj
@@ -4,4 +4,7 @@
     <LangVersion>latest</LangVersion>
     <Nullable>enable</Nullable>
   </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Logging" Version="9.0.1" />
+  </ItemGroup>
 </Project>  
\ No newline at end of file
diff --git a/RateLimiter/Rules/FixedWindowRule.cs b/RateLimiter/Rules/FixedWindowRule.cs
new file mode 100644
index 00000000..01e4eb83
--- /dev/null
+++ b/RateLimiter/Rules/FixedWindowRule.cs
@@ -0,0 +1,45 @@
+using System;
+using System.Collections.Concurrent;
+
+namespace RateLimiter.Rules
+{
+    public class FixedWindowRule : IRateLimitRule
+    {
+        private readonly int _limit;
+        private readonly TimeSpan _window;
+        private readonly ConcurrentDictionary<string, (int count, DateTime resetTime)> _requests = new();
+
+        public FixedWindowRule(int limit, TimeSpan window)
+        {
+            _limit = limit;
+            _window = window;
+        }
+
+        public bool IsAllowed(string clientId, string resource)
+        {
+            var key = $"{clientId}:{resource}";
+            var now = DateTime.UtcNow;
+
+            _requests.AddOrUpdate(key, _ => (1, now + _window), (_, entry) =>
+            {
+                if (entry.resetTime <= now)
+                    return (1, now + _window);
+                return (entry.count + 1, entry.resetTime);
+            });
+
+            return _requests[key].count <= _limit;
+        }
+
+        public void Cleanup()
+        {
+            var now = DateTime.UtcNow;
+            foreach (var key in _requests.Keys)
+            {
+                if (_requests.TryGetValue(key, out var entry) && entry.resetTime <= now)
+                {
+                    _requests.TryRemove(key, out _);
+                }
+            }
+        }
+    }
+}
diff --git a/RateLimiter/Rules/IRateLimitRule.cs b/RateLimiter/Rules/IRateLimitRule.cs
new file mode 100644
index 00000000..cea73c0c
--- /dev/null
+++ b/RateLimiter/Rules/IRateLimitRule.cs
@@ -0,0 +1,8 @@
+namespace RateLimiter.Rules
+{
+    public interface IRateLimitRule
+    {
+        bool IsAllowed(string clientId, string resource);
+        void Cleanup();
+    }
+}
diff --git a/RateLimiter/Rules/RegionalRule.cs b/RateLimiter/Rules/RegionalRule.cs
new file mode 100644
index 00000000..e6c4a0a3
--- /dev/null
+++ b/RateLimiter/Rules/RegionalRule.cs
@@ -0,0 +1,36 @@
+using System.Collections.Generic;
+
+namespace RateLimiter.Rules
+{
+    public class RegionalRule : IRateLimitRule
+    {
+        private readonly Dictionary<string, IRateLimitRule> _regionRules;
+
+        public RegionalRule(Dictionary<string, IRateLimitRule> regionRules)
+        {
+            _regionRules = regionRules;
+        }
+
+        public bool IsAllowed(string clientId, string resource)
+        {
+            var region = GetRegionFromClient(clientId);
+            return _regionRules.TryGetValue(region, out var rule) && rule.IsAllowed(clientId, resource);
+        }
+
+        private string GetRegionFromClient(string clientId)
+        {
+            if (clientId.StartsWith("US-")) return "US";
+            if (clientId.StartsWith("EU-")) return "EU";
+            if (clientId.StartsWith("ASIA-")) return "ASIA";
+            return "GLOBAL";
+        }
+
+        public void Cleanup()
+        {
+            foreach (var rule in _regionRules.Values)
+            {
+                rule.Cleanup();
+            }
+        }
+    }
+}
diff --git a/RateLimiter/Rules/SlidingWindowRule.cs b/RateLimiter/Rules/SlidingWindowRule.cs
new file mode 100644
index 00000000..35bb0670
--- /dev/null
+++ b/RateLimiter/Rules/SlidingWindowRule.cs
@@ -0,0 +1,48 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+
+namespace RateLimiter.Rules
+{
+    public class SlidingWindowRule : IRateLimitRule
+    {
+        private readonly int _limit;
+        private readonly TimeSpan _window;
+        private readonly ConcurrentDictionary<string, Queue<DateTime>> _requests = new();
+
+        public SlidingWindowRule(int limit, TimeSpan window)
+        {
+            _limit = limit;
+            _window = window;
+        }
+
+        public bool IsAllowed(string clientId, string resource)
+        {
+            var key = $"{clientId}:{resource}";
+            var now = DateTime.UtcNow;
+
+            _requests.AddOrUpdate(key, _ => new Queue<DateTime>(new[] { now }), (_, queue) =>
+            {
+                while (queue.Count > 0 && queue.Peek() <= now - _window)
+                    queue.Dequeue();
+                queue.Enqueue(now);
+                return queue;
+            });
+
+            return _requests[key].Count <= _limit;
+        }
+
+        public void Cleanup()
+        {
+            var now = DateTime.UtcNow;
+            foreach (var key in _requests.Keys)
+            {
+                if (_requests.TryGetValue(key, out var queue))
+                {
+                    while (queue.Count > 0 && queue.Peek() <= now - _window)
+                        queue.Dequeue();
+                }
+            }
+        }
+    }
+}