⚠️ This repository is under active development. The service will be live soon. Stay tuned! ⚠️

👋 Welcome to Finnhub MCP Server

🎯 Project Overview

A robust Model Context Protocol (MCP) Server that integrates with Finnhub's institutional-grade financial data APIs. Provides both Server-Sent Events (SSE) and Standard Input/Output (STDIO) transport protocols for streaming live financial data with modern .NET practices and Finnhub API best practices.

🚀 Key Features

• ✅ Symbol Search Tool with validated and sanitized user input
• ✅ Finnhub API Rate Limiting
  • Respects free tier limits (60 requests/minute)
  • Implements exponential backoff for 429 responses
  • Configurable rate limiting for different subscription tiers
• ✅ Robust Input Validation
  • Query & exchange inputs sanitized using regex patterns
  • Length and pattern constraints enforced at runtime and via JSON Schema
  • Symbol validation against Finnhub's supported formats
• ✅ Secure by Default
  • Actively defends against common injection vectors (<script>, SQL-style, etc.)
  • Allowed character sets enforced through schema and code
  • API key stored securely via environment variables
• ✅ Resilient HTTP Communication
  • Typed HttpClient with retry & circuit breaker policies (via Polly)
  • Connection pooling with SocketsHttpHandler
  • Automatic retry with jitter for failed requests
• ✅ WebSocket Support (Coming Soon)
  • Real-time streaming via Finnhub WebSocket API
  • Automatic reconnection handling
  • Subscription management for multiple symbols

📊 Finnhub API Integration & Best Practices

This server implements Finnhub's recommended best practices:

Rate Limiting

• Free Tier: 60 requests/minute with automatic throttling
• Premium Tiers: Configurable limits based on your subscription
• Implements exponential backoff for rate limit responses (HTTP 429)
• Request queuing to prevent API limit violations

Error Handling

• Comprehensive error handling for all Finnhub API responses
• Graceful degradation when API is unavailable
• Retry logic with exponential backoff for transient failures
• Proper handling of 401 (Unauthorized) and 429 (Rate Limit) responses

Data Validation

• Input sanitization for all symbol and parameter inputs
• Validates symbols against Finnhub's supported formats
• Exchange code validation for international markets
• Query parameter encoding to prevent injection attacks

Performance Optimization

• HTTP connection pooling and reuse
• Efficient JSON deserialization with System.Text.Json
• Async/await patterns throughout for non-blocking operations
• Memory-efficient streaming for large datasets

🚧 Available & Upcoming MCP Tools

✅ Currently Available

• Symbol Search Tool — search for stock symbols with fuzzy matching

🔄 In Development

• Real-Time Quote Tool — live prices for stock, forex & crypto
• Company Profile Tool — detailed company information and metrics
• Basic Financial Tool — key financial metrics and ratios

📋 Planned Features

• Advanced Fundamentals Tool — comprehensive financial statements
• Earnings Calendar Tool — track earnings release dates and estimates
• News & Sentiment Tool — company news with sentiment analysis
• Insider Trading Tool — insider transaction data
• Market Status Tool — trading hours and market holidays
• Technical Indicators — RSI, MACD, moving averages
• Economic Data Tool — GDP, inflation, employment data
• Crypto Data Tool — cryptocurrency prices and market data

🚀 Getting Started

📋 Prerequisites

• .NET 8 SDK or later
• A valid Finnhub API Key (free tier available)

🔑 Getting Your Finnhub API Key

1. Visit Finnhub.io and create a free account
2. Navigate to your Dashboard
3. Copy your API key from the dashboard
4. Note: Free tier provides 60 requests/minute and access to basic market data

📦 Installation

git clone https://github.com/SalZaki/finnhub-mcp.git
cd finnhub-mcp
dotnet restore

🔐 API Key Configuration

Security Note: Never commit your API key to version control. Always use environment variables or secure configuration management.

Option 1: Environment Variable (Recommended)

macOS/Linux:

export FINNHUB_API_KEY="your_api_key_here"

Windows PowerShell:

$env:FINNHUB_API_KEY="your_api_key_here"

Windows Command Prompt:

set FINNHUB_API_KEY=your_api_key_here

Option 2: .env File (Development Only)

Create a .env file in the root directory:

echo "FINNHUB_API_KEY=your_api_key_here" > .env

Important: The .env file is automatically loaded during development but should never be committed to version control.

🚀 Running the Server

HTTP Transport (Default)

dotnet run --project src/FinnHub.MCP.Server --urls http://localhost:5101

STDIO Transport

dotnet run --project src/FinnHub.MCP.Server -- --stdio

Docker Support

docker build -t finnhub-mcp .
docker run -e FINNHUB_API_KEY="your_api_key_here" -p 5101:5101 finnhub-mcp

📖 API Usage Examples

Symbol Search

# Search for Apple stock
curl -X POST "http://localhost:5101/mcp/tools/symbol_search" \
  -H "Content-Type: application/json" \
  -d '{"query": "AAPL"}'

Real-Time Quote (Coming Soon)

# Get real-time quote for Apple
curl -X POST "http://localhost:5101/mcp/tools/quote" \
  -H "Content-Type: application/json" \
  -d '{"symbol": "AAPL"}'

⚙️ Configuration

Rate Limiting Configuration

{
  "Finnhub": {
    "RateLimit": {
      "RequestsPerMinute": 60,
      "BurstLimit": 10,
      "RetryAfterSeconds": 60
    }
  }
}

Logging Configuration

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "FinnHub.MCP.Server": "Debug",
      "Microsoft.AspNetCore": "Warning"
    }
  }
}

🧪 Testing

Unit Tests

dotnet test src/FinnHub.MCP.Server.Tests

Integration Tests

# Set test API key
export FINNHUB_TEST_API_KEY="your_test_api_key"
dotnet test src/FinnHub.MCP.Server.IntegrationTests

Load Testing

# Test rate limiting behavior
dotnet run --project tests/FinnHub.MCP.LoadTests

🔧 Development

Building from Source

dotnet build

Running with Hot Reload

dotnet watch run --project src/FinnHub.MCP.Server

Code Quality

# Run code analysis
dotnet format
dotnet run --project tools/CodeAnalysis

📊 Monitoring & Observability

• Health Checks: /health endpoint for monitoring
• Metrics: Prometheus metrics via /metrics
• Tracing: OpenTelemetry integration
• Logging: Structured logging with Serilog

🛠️ Tech Stack

• Framework: .NET 8 with ASP.NET Core
• Resilience: Polly for retry policies and circuit breakers
• Validation: JsonSchema.Net for input validation
• Testing: xUnit with Moq for mocking
• Configuration: DotNetEnv for environment management
• Logging: Serilog for structured logging
• Monitoring: OpenTelemetry for observability
• CI/CD: GitHub Actions with automated testing and deployment

Development Setup

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Add tests for new functionality
5. Ensure all tests pass (dotnet test)
6. Submit a pull request

📄 License

This project is licensed under the MIT License, see LICENSE file for details.

🙏 Acknowledgments

• FinnHub.io for providing excellent financial data APIs
• Model Context Protocol for the MCP specification
• The .NET community for excellent libraries and tools

📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Documentation: Wiki
• Finnhub Support: Finnhub Documentation