API Gateway Comparison: Ocelot vs YARP vs Kong - Complete Analysis 2025

Choosing the right API gateway is crucial for building scalable, maintainable microservices architectures. With multiple options available for .NET developers, understanding the differences between Ocelot, YARP, and Kong is essential for making informed decisions. In this comprehensive comparison, we'll analyze features, performance, use cases, and provide implementation examples to help you choose the best API gateway for your needs.

Understanding API Gateways

What is an API Gateway?

An API gateway is a service that sits between clients and backend services, providing:

• Request routing - Direct requests to appropriate services
• Load balancing - Distribute traffic across multiple instances
• Authentication & authorization - Centralized security management
• Rate limiting - Control request frequency and volume
• Monitoring & logging - Centralized observability
• Transformation - Request/response modification
• Caching - Improve performance with response caching

Why Use an API Gateway?

Benefits:

• Simplified client communication - Single entry point for all services
• Centralized cross-cutting concerns - Security, logging, monitoring
• Service decoupling - Clients don't need to know service locations
• Traffic management - Load balancing, circuit breaking, retry logic
• API versioning - Manage multiple API versions seamlessly

Ocelot: .NET Native API Gateway

Overview

Ocelot is a .NET-based API gateway designed specifically for .NET applications. It's lightweight, easy to configure, and integrates seamlessly with the .NET ecosystem.

Key Features

• .NET native - Built specifically for .NET applications
• JSON configuration - Simple configuration management
• Middleware pipeline - Extensible middleware architecture
• Service discovery - Integration with Consul, Eureka, and other registries
• Load balancing - Round-robin, least connections, and custom algorithms
• Rate limiting - Built-in rate limiting capabilities
• Authentication - JWT, OAuth2, and custom authentication
• Caching - Response caching with configurable policies

Implementation Example

// Program.cs
var builder = WebApplication.CreateBuilder(args);

// Add Ocelot
builder.Services.AddOcelot()
    .AddConsul()
    .AddCacheManager(x => x.WithDictionaryHandle());

var app = builder.Build();

// Use Ocelot
app.UseOcelot().Wait();

app.Run();

// ocelot.json
{
  "Routes": [
    {
      "DownstreamPathTemplate": "/api/users/{id}",
      "DownstreamScheme": "https",
      "DownstreamHostAndPorts": [
        {
          "Host": "user-service",
          "Port": 80
        }
      ],
      "UpstreamPathTemplate": "/users/{id}",
      "UpstreamHttpMethod": ["GET"],
      "AuthenticationOptions": {
        "AuthenticationProviderKey": "Bearer",
        "AllowedScopes": ["user.read"]
      },
      "RateLimitOptions": {
        "ClientWhitelist": [],
        "EnableRateLimiting": true,
        "Period": "1m",
        "PeriodTimespan": 60,
        "Limit": 100
      }
    }
  ],
  "GlobalConfiguration": {
    "BaseUrl": "https://api.example.com",
    "ServiceDiscoveryProvider": {
      "Type": "Consul",
      "Host": "consul",
      "Port": 8500
    }
  }
}

Pros and Cons

Pros:

• Native .NET integration
• Simple configuration
• Good performance for .NET workloads
• Extensive middleware support
• Active community

Cons:

• Limited to .NET ecosystem
• Fewer advanced features compared to enterprise solutions
• Configuration can become complex for large systems
• Limited monitoring and observability features

YARP: Yet Another Reverse Proxy

Overview

YARP (Yet Another Reverse Proxy) is Microsoft's modern reverse proxy solution built on .NET 6+. It's designed to be fast, lightweight, and highly configurable.

Key Features

• High performance - Built for speed and efficiency
• Configuration flexibility - Code-based and file-based configuration
• Load balancing - Multiple load balancing algorithms
• Health checks - Built-in health checking capabilities
• Transforms - Request/response transformation
• Authentication - Integration with ASP.NET Core authentication
• Metrics - Built-in metrics and monitoring

Implementation Example

// Program.cs
var builder = WebApplication.CreateBuilder(args);

// Add YARP
builder.Services.AddReverseProxy()
    .LoadFromConfig(builder.Configuration.GetSection("ReverseProxy"));

var app = builder.Build();

// Use YARP
app.MapReverseProxy();

app.Run();

// appsettings.json
{
  "ReverseProxy": {
    "Routes": {
      "user-route": {
        "ClusterId": "user-cluster",
        "Match": {
          "Path": "/users/{**catch-all}"
        }
      }
    },
    "Clusters": {
      "user-cluster": {
        "Destinations": {
          "user-service": {
            "Address": "https://user-service:80/"
          }
        },
        "LoadBalancingPolicy": "RoundRobin"
      }
    }
  }
}

Advanced YARP Configuration

// Advanced YARP configuration
public class CustomProxyConfigProvider : IProxyConfigProvider
{
    public IProxyConfig GetConfig()
    {
        var routes = new[]
        {
            new RouteConfig
            {
                RouteId = "user-route",
                ClusterId = "user-cluster",
                Match = new RouteMatch
                {
                    Path = "/users/{**catch-all}"
                },
                Transforms = new[]
                {
                    new Dictionary<string, string>
                    {
                        ["PathPattern"] = "/api/users/{**catch-all}"
                    }
                }
            }
        };

        var clusters = new[]
        {
            new ClusterConfig
            {
                ClusterId = "user-cluster",
                LoadBalancingPolicy = "RoundRobin",
                Destinations = new Dictionary<string, DestinationConfig>
                {
                    ["user-service-1"] = new DestinationConfig
                    {
                        Address = "https://user-service-1:80/"
                    },
                    ["user-service-2"] = new DestinationConfig
                    {
                        Address = "https://user-service-2:80/"
                    }
                },
                HealthCheck = new HealthCheckConfig
                {
                    Active = new ActiveHealthCheckConfig
                    {
                        Enabled = true,
                        Interval = TimeSpan.FromSeconds(30),
                        Path = "/health"
                    }
                }
            }
        };

        return new ProxyConfig(routes, clusters);
    }
}

Pros and Cons

Pros:

• High performance
• Modern .NET architecture
• Flexible configuration
• Built-in health checks
• Microsoft support
• Lightweight

Cons:

• Newer solution with smaller ecosystem
• Limited enterprise features
• Requires more custom development
• Less mature than established solutions

Kong: Enterprise API Gateway

Overview

Kong is a mature, feature-rich API gateway that supports multiple deployment models and provides extensive enterprise features.

Key Features

• Multi-platform - Supports multiple deployment models
• Plugin ecosystem - Extensive plugin library
• Enterprise features - Advanced security, monitoring, and management
• Multi-protocol - HTTP, HTTPS, gRPC, WebSocket support
• Database support - PostgreSQL, Cassandra, and more
• Cloud native - Kubernetes, Docker, and cloud platform support
• API management - Developer portal, API documentation

Implementation Example

# kong.yml
_format_version: "3.0"

services:
  - name: user-service
    url: https://user-service:80/
    routes:
      - name: user-route
        paths:
          - /users
        methods:
          - GET
          - POST
        plugins:
          - name: rate-limiting
            config:
              minute: 100
              hour: 1000
          - name: jwt
            config:
              secret_is_base64: false
              key_claim_name: iss
              claims_to_verify:
                - exp
                - iss

plugins:
  - name: cors
    config:
      origins:
        - "*"
      methods:
        - GET
        - POST
        - PUT
        - DELETE
      headers:
        - Accept
        - Accept-Version
        - Content-Length
        - Content-MD5
        - Content-Type
        - Date
        - X-Auth-Token
      exposed_headers:
        - X-Auth-Token
      credentials: true
      max_age: 3600

Kong with .NET Integration

// Kong client for .NET
public class KongApiClient
{
    private readonly HttpClient _httpClient;
    private readonly string _kongAdminUrl;
    
    public KongApiClient(HttpClient httpClient, IConfiguration configuration)
    {
        _httpClient = httpClient;
        _kongAdminUrl = configuration["Kong:AdminUrl"];
    }
    
    public async Task<Service> CreateServiceAsync(CreateServiceRequest request)
    {
        var response = await _httpClient.PostAsJsonAsync(
            $"{_kongAdminUrl}/services", request);
        response.EnsureSuccessStatusCode();
        
        return await response.Content.ReadFromJsonAsync<Service>();
    }
    
    public async Task<Route> CreateRouteAsync(string serviceId, CreateRouteRequest request)
    {
        var response = await _httpClient.PostAsJsonAsync(
            $"{_kongAdminUrl}/services/{serviceId}/routes", request);
        response.EnsureSuccessStatusCode();
        
        return await response.Content.ReadFromJsonAsync<Route>();
    }
    
    public async Task<Plugin> AddPluginAsync(string serviceId, AddPluginRequest request)
    {
        var response = await _httpClient.PostAsJsonAsync(
            $"{_kongAdminUrl}/services/{serviceId}/plugins", request);
        response.EnsureSuccessStatusCode();
        
        return await response.Content.ReadFromJsonAsync<Plugin>();
    }
}

Pros and Cons

Pros:

• Mature and battle-tested
• Extensive plugin ecosystem
• Enterprise features
• Multi-platform support
• Strong community
• Excellent documentation

Cons:

• Higher resource requirements
• More complex setup
• Learning curve for .NET developers
• Potential overkill for simple use cases

Performance Comparison

Benchmark Results

Performance Analysis

Ocelot:

• Good performance for .NET workloads
• Higher memory usage due to .NET runtime
• Suitable for medium-scale applications

YARP:

• Best performance among .NET solutions
• Lowest resource usage
• Ideal for high-performance scenarios

Kong:

• Good performance with extensive features
• Higher resource requirements
• Best for enterprise-scale applications

Feature Comparison Matrix

Use Case Recommendations

Choose Ocelot When:

• Building .NET microservices
• Need simple configuration
• Want .NET-native solution
• Have medium-scale requirements
• Need quick setup and deployment

Example Implementation:

// Ocelot for .NET microservices
public class MicroservicesGateway
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddOcelot()
            .AddConsul()
            .AddCacheManager(x => x.WithDictionaryHandle());
    }
}

Choose YARP When:

• Need maximum performance
• Building modern .NET applications
• Want Microsoft-supported solution
• Have high-throughput requirements
• Prefer code-based configuration

Example Implementation:

// YARP for high-performance scenarios
public class HighPerformanceGateway
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddReverseProxy()
            .LoadFromConfig(Configuration.GetSection("ReverseProxy"));
    }
}

Choose Kong When:

• Need enterprise features
• Building multi-platform solutions
• Require extensive plugin ecosystem
• Have complex routing requirements
• Need advanced monitoring and management

Example Implementation:

# Kong for enterprise scenarios
services:
  - name: api-gateway
    url: https://backend-service:80/
    routes:
      - name: api-route
        paths:
          - /api
        plugins:
          - name: rate-limiting
          - name: jwt
          - name: cors

Implementation Best Practices

1. Configuration Management

// Centralized configuration
public class GatewayConfiguration
{
    public string BaseUrl { get; set; }
    public List<RouteConfiguration> Routes { get; set; }
    public AuthenticationConfiguration Authentication { get; set; }
    public RateLimitingConfiguration RateLimiting { get; set; }
}

public class RouteConfiguration
{
    public string Name { get; set; }
    public string UpstreamPath { get; set; }
    public string DownstreamPath { get; set; }
    public string DownstreamHost { get; set; }
    public int DownstreamPort { get; set; }
    public List<string> UpstreamMethods { get; set; }
}

2. Health Monitoring

// Health monitoring for API gateway
public class GatewayHealthService
{
    private readonly ILogger<GatewayHealthService> _logger;
    private readonly List<IServiceHealthChecker> _healthCheckers;
    
    public async Task<HealthStatus> CheckHealthAsync()
    {
        var healthTasks = _healthCheckers.Select(checker => 
            checker.CheckHealthAsync());
        
        var results = await Task.WhenAll(healthTasks);
        
        var overallHealth = results.All(r => r.IsHealthy) 
            ? HealthStatus.Healthy 
            : HealthStatus.Unhealthy;
            
        return new HealthStatus
        {
            OverallHealth = overallHealth,
            ServiceHealth = results.ToList(),
            Timestamp = DateTime.UtcNow
        };
    }
}

3. Error Handling

// Centralized error handling
public class GatewayErrorHandler
{
    private readonly ILogger<GatewayErrorHandler> _logger;
    
    public async Task<ErrorResponse> HandleErrorAsync(Exception exception, HttpContext context)
    {
        _logger.LogError(exception, "Gateway error occurred");
        
        return exception switch
        {
            ServiceUnavailableException => new ErrorResponse
            {
                StatusCode = 503,
                Message = "Service temporarily unavailable",
                ErrorCode = "SERVICE_UNAVAILABLE"
            },
            RateLimitExceededException => new ErrorResponse
            {
                StatusCode = 429,
                Message = "Rate limit exceeded",
                ErrorCode = "RATE_LIMIT_EXCEEDED"
            },
            UnauthorizedException => new ErrorResponse
            {
                StatusCode = 401,
                Message = "Unauthorized",
                ErrorCode = "UNAUTHORIZED"
            },
            _ => new ErrorResponse
            {
                StatusCode = 500,
                Message = "Internal server error",
                ErrorCode = "INTERNAL_ERROR"
            }
        };
    }
}

Migration Strategies

From Ocelot to YARP

// Migration from Ocelot to YARP
public class OcelotToYarpMigration
{
    public void MigrateConfiguration(OcelotConfiguration ocelotConfig)
    {
        var yarpConfig = new YarpConfiguration();
        
        foreach (var route in ocelotConfig.Routes)
        {
            var yarpRoute = new RouteConfig
            {
                RouteId = route.Key,
                ClusterId = $"{route.Key}-cluster",
                Match = new RouteMatch
                {
                    Path = route.Value.UpstreamPathTemplate
                }
            };
            
            yarpConfig.Routes.Add(yarpRoute);
            
            var cluster = new ClusterConfig
            {
                ClusterId = $"{route.Key}-cluster",
                Destinations = new Dictionary<string, DestinationConfig>
                {
                    ["destination1"] = new DestinationConfig
                    {
                        Address = $"{route.Value.DownstreamScheme}://{route.Value.DownstreamHostAndPorts[0].Host}:{route.Value.DownstreamHostAndPorts[0].Port}"
                    }
                }
            };
            
            yarpConfig.Clusters.Add(cluster);
        }
    }
}

From YARP to Kong

# Migration from YARP to Kong
services:
  - name: migrated-service
    url: https://backend-service:80/
    routes:
      - name: migrated-route
        paths:
          - /api/users
        methods:
          - GET
          - POST
        plugins:
          - name: rate-limiting
            config:
              minute: 100
          - name: jwt
            config:
              secret_is_base64: false

Monitoring and Observability

1. Metrics Collection

// Metrics collection for API gateway
public class GatewayMetricsService
{
    private readonly IMetricsCollector _metricsCollector;
    
    public void RecordRequest(string route, string method, int statusCode, long duration)
    {
        _metricsCollector.RecordCounter("gateway.requests.total", 1, 
            new Dictionary<string, string>
            {
                ["route"] = route,
                ["method"] = method,
                ["status_code"] = statusCode.ToString()
            });
            
        _metricsCollector.RecordHistogram("gateway.request.duration", duration,
            new Dictionary<string, string>
            {
                ["route"] = route,
                ["method"] = method
            });
    }
}

2. Logging Strategy

// Structured logging for API gateway
public class GatewayLoggingService
{
    private readonly ILogger<GatewayLoggingService> _logger;
    
    public void LogRequest(string requestId, string route, string method, 
        string clientIp, long duration)
    {
        _logger.LogInformation("Request processed: {RequestId} {Route} {Method} {ClientIp} {Duration}ms",
            requestId, route, method, clientIp, duration);
    }
    
    public void LogError(string requestId, string route, Exception exception)
    {
        _logger.LogError(exception, "Request failed: {RequestId} {Route}",
            requestId, route);
    }
}

Security Considerations

1. Authentication and Authorization

// Authentication middleware for API gateway
public class AuthenticationMiddleware
{
    private readonly RequestDelegate _next;
    private readonly IAuthenticationService _authService;
    
    public async Task InvokeAsync(HttpContext context)
    {
        var token = ExtractToken(context);
        
        if (string.IsNullOrEmpty(token))
        {
            context.Response.StatusCode = 401;
            return;
        }
        
        var user = await _authService.ValidateTokenAsync(token);
        if (user == null)
        {
            context.Response.StatusCode = 401;
            return;
        }
        
        context.User = user;
        await _next(context);
    }
}

2. Rate Limiting

// Rate limiting implementation
public class RateLimitingMiddleware
{
    private readonly RequestDelegate _next;
    private readonly IRateLimitingService _rateLimitingService;
    
    public async Task InvokeAsync(HttpContext context)
    {
        var clientId = GetClientId(context);
        var route = GetRoute(context);
        
        if (!await _rateLimitingService.IsAllowedAsync(clientId, route))
        {
            context.Response.StatusCode = 429;
            context.Response.Headers.Add("Retry-After", "60");
            return;
        }
        
        await _next(context);
    }
}

Conclusion

Choosing the right API gateway depends on your specific requirements, scale, and ecosystem. Ocelot is ideal for .NET-focused teams, YARP offers the best performance for modern .NET applications, and Kong provides the most comprehensive enterprise features.

Key takeaways:

• Ocelot - Best for .NET teams with simple to medium requirements
• YARP - Ideal for high-performance .NET applications
• Kong - Perfect for enterprise scenarios with complex requirements
• Consider your team's expertise, performance needs, and feature requirements
• Plan for monitoring, security, and scalability from the start

Ready to implement an API gateway for your .NET application? Our team at Elysiate can help you choose the right solution and implement it effectively. Contact us to learn more about our API gateway services.

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