Chi API Security

Chi (go-chi/chi) is a lightweight, idiomatic HTTP router for Go that provides a solid foundation for building APIs. The framework itself takes a minimalist approach, offering essential routing capabilities without imposing security defaults. This design philosophy means Chi is secure by omission rather than by default — it gives you the tools but doesn't enforce security patterns.

Chi's core strengths include context-based request handling, middleware support, and clean URL routing. However, these same features can become security liabilities when developers don't actively implement proper protections. The framework doesn't include built-in authentication, rate limiting, or input validation middleware, which means every Chi API requires deliberate security configuration.

Unlike frameworks that bundle security middleware, Chi's approach gives developers complete control but also complete responsibility. This makes it particularly important to understand where Chi's defaults leave gaps and how to properly secure your API endpoints.

Missing Authentication Middleware
Chi doesn't enforce authentication — developers must explicitly add middleware. A common mistake is forgetting to protect admin routes or leaving development endpoints exposed in production. Without authentication middleware, any endpoint is accessible to anyone who discovers it.

Improper Path Parameter Validation
Chi's flexible routing can lead to path traversal vulnerabilities when parameters aren't properly validated. Routes like /users/{id} without validation can be exploited for BOLA (Broken Object Level Authorization) attacks, allowing attackers to access other users' data by manipulating ID parameters.

Missing Rate Limiting
The framework provides no built-in rate limiting. APIs without rate limiting are vulnerable to brute force attacks, credential stuffing, and DoS attacks. Many developers forget to implement rate limiting until after a security incident.

Unsafe CORS Configuration
Chi's CORS middleware is often misconfigured with overly permissive settings. Using AllowedOrigins: ["*"] or allowing all methods/headers can expose your API to cross-origin attacks and data exfiltration.

Missing Security Headers
Chi doesn't set security headers by default. APIs missing headers like X-Content-Type-Options, X-Frame-Options, or Content-Security-Policy are vulnerable to MIME-type confusion, clickjacking, and other client-side attacks.

Authentication & Authorization
Always implement authentication middleware for protected routes. Use JWT middleware or similar for API authentication, and ensure admin endpoints are properly protected. Implement role-based access control to prevent privilege escalation.

router.Use(jwtMiddleware)
router.Group(func(r chi.Router) {
    r.Use(authMiddleware)
    r.Get("/admin", adminHandler)
})

Input Validation
Validate all path parameters, query parameters, and request bodies. Use regex patterns for IDs, enforce length limits, and validate against expected formats. Never trust client-provided data.

router.Get("/users/{id:[0-9]+}", func(w http.ResponseWriter, r *http.Request) {
    id := chi.URLParam(r, "id")
    // Validate id format before using
})

Rate Limiting
Implement rate limiting middleware to protect against abuse. Rate limit by IP address for public APIs and by user for authenticated endpoints. Set appropriate limits based on your API's expected usage patterns.

router.Use(middleware.RateLimiter(10, time.Minute))

CORS Configuration
Configure CORS with specific origins rather than wildcards. Only allow necessary HTTP methods and headers. For APIs that don't need CORS, disable it entirely.

router.Use(middleware.CORS(middleware.CORSOptions{
    AllowedOrigins:   []string{"https://yourdomain.com"},
    AllowedMethods:   []string{"GET", "POST", "PUT"},
    AllowedHeaders:   []string{"Authorization", "Content-Type"},
}))

Security Headers
Add security headers middleware to protect against common web vulnerabilities. Set appropriate headers for your API's needs and test that they're being sent correctly.

router.Use(middleware.SetHeader("X-Content-Type-Options", "nosniff"))
router.Use(middleware.SetHeader("X-Frame-Options", "DENY"))

Logging & Monitoring
Implement comprehensive logging for security events. Log authentication failures, rate limit hits, and suspicious patterns. Use structured logging to make security analysis easier.

API Scanning
Before deploying to production, scan your Chi API with middleBrick to identify security vulnerabilities. The scanner tests for authentication bypasses, authorization flaws, and other common security issues without requiring credentials or configuration.