diff --git a/README.md b/README.md
index 2864bcd..d2f5113 100644
--- a/README.md
+++ b/README.md
@@ -7,9 +7,10 @@ A lightweight LLM proxy gateway written in Go that provides a unified API interf
 ## Purpose
 
 Simplify LLM integration by exposing a single, consistent API that routes requests to different providers:
-- **Google Generative AI** (Gemini)
-- **Anthropic** (Claude)
 - **OpenAI** (GPT models)
+- **Azure OpenAI** (Azure-deployed models)
+- **Anthropic** (Claude)
+- **Google Generative AI** (Gemini)
 
 Instead of managing multiple SDK integrations in your application, call one endpoint and let the gateway handle provider-specific implementations.
 
@@ -20,9 +21,10 @@ Client Request
     ↓
 Go LLM Gateway (unified API)
     ↓
-├─→ Google Gen AI SDK
+├─→ OpenAI SDK
+├─→ Azure OpenAI (OpenAI SDK + Azure auth)
 ├─→ Anthropic SDK
-└─→ OpenAI SDK
+└─→ Google Gen AI SDK
 ```
 
 ## Key Features
@@ -43,13 +45,14 @@ Go LLM Gateway (unified API)
 
 ## 🎉 Status: **WORKING!**
 
-✅ **All three providers integrated with official Go SDKs:**
+✅ **All four providers integrated with official Go SDKs:**
 - OpenAI → `github.com/openai/openai-go`
+- Azure OpenAI → `github.com/openai/openai-go` (with Azure auth)
 - Anthropic → `github.com/anthropics/anthropic-sdk-go`
 - Google → `google.golang.org/genai`
 
 ✅ **Compiles successfully** (36MB binary)
-✅ **Provider auto-selection** (gpt→OpenAI, claude→Anthropic, gemini→Google)
+✅ **Provider auto-selection** (gpt→Azure/OpenAI, claude→Anthropic, gemini→Google)
 ✅ **Configuration system** (YAML with env var support)
 ✅ **Streaming support** (Server-Sent Events for all providers)
 ✅ **OAuth2/OIDC authentication** (Google, Auth0, any OIDC provider)
@@ -202,6 +205,28 @@ The gateway implements conversation tracking using `previous_response_id` from t
 
 See **[CONVERSATIONS.md](./CONVERSATIONS.md)** for details.
 
+## Azure OpenAI
+
+The gateway supports Azure OpenAI with the same interface as standard OpenAI:
+
+```yaml
+providers:
+  azureopenai:
+    api_key: "${AZURE_OPENAI_API_KEY}"
+    endpoint: "https://your-resource.openai.azure.com"
+    deployment_id: "your-deployment-name"
+```
+
+```bash
+export AZURE_OPENAI_API_KEY="..."
+export AZURE_OPENAI_ENDPOINT="https://your-resource.openai.azure.com"
+export AZURE_OPENAI_DEPLOYMENT_ID="gpt-4o"
+
+./gateway
+```
+
+The gateway prefers Azure OpenAI for `gpt-*` models if configured. See **[AZURE_OPENAI.md](./AZURE_OPENAI.md)** for complete setup guide.
+
 ## Authentication
 
 The gateway supports OAuth2/OIDC authentication. See **[AUTH.md](./AUTH.md)** for setup instructions.
diff --git a/go.mod b/go.mod
index 160dbd4..4f8ed23 100644
--- a/go.mod
+++ b/go.mod
@@ -14,22 +14,26 @@ require (
 	cloud.google.com/go v0.116.0 // indirect
 	cloud.google.com/go/auth v0.9.3 // indirect
 	cloud.google.com/go/compute/metadata v0.5.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/ai/azopenai v0.9.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/azcore v1.21.0 // indirect
+	github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.1 // indirect
 	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/google/go-cmp v0.6.0 // indirect
 	github.com/google/s2a-go v0.1.8 // indirect
 	github.com/googleapis/enterprise-certificate-proxy v0.3.4 // indirect
 	github.com/gorilla/websocket v1.5.3 // indirect
+	github.com/openai/openai-go/v3 v3.2.0 // indirect
 	github.com/tidwall/gjson v1.18.0 // indirect
 	github.com/tidwall/match v1.1.1 // indirect
 	github.com/tidwall/pretty v1.2.1 // indirect
 	github.com/tidwall/sjson v1.2.5 // indirect
 	go.opencensus.io v0.24.0 // indirect
-	golang.org/x/crypto v0.40.0 // indirect
-	golang.org/x/net v0.41.0 // indirect
-	golang.org/x/sync v0.16.0 // indirect
-	golang.org/x/sys v0.34.0 // indirect
-	golang.org/x/text v0.27.0 // indirect
+	golang.org/x/crypto v0.47.0 // indirect
+	golang.org/x/net v0.49.0 // indirect
+	golang.org/x/sync v0.19.0 // indirect
+	golang.org/x/sys v0.40.0 // indirect
+	golang.org/x/text v0.33.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240903143218-8af14fe29dc1 // indirect
 	google.golang.org/grpc v1.66.2 // indirect
 	google.golang.org/protobuf v1.34.2 // indirect
diff --git a/go.sum b/go.sum
index 18f27ce..be24977 100644
--- a/go.sum
+++ b/go.sum
@@ -5,6 +5,12 @@ cloud.google.com/go/auth v0.9.3 h1:VOEUIAADkkLtyfr3BLa3R8Ed/j6w1jTBmARx+wb5w5U=
 cloud.google.com/go/auth v0.9.3/go.mod h1:7z6VY+7h3KUdRov5F1i8NDP5ZzWKYmEPO842BgCsmTk=
 cloud.google.com/go/compute/metadata v0.5.0 h1:Zr0eK8JbFv6+Wi4ilXAR8FJ3wyNdpxHKJNPos6LTZOY=
 cloud.google.com/go/compute/metadata v0.5.0/go.mod h1:aHnloV2TPI38yx4s9+wAZhHykWvVCfu7hQbF+9CWoiY=
+github.com/Azure/azure-sdk-for-go/sdk/ai/azopenai v0.9.0 h1:t/DLMixbb8ygU11RAHJ8quXwJD7FwlC7+u6XodmSi1w=
+github.com/Azure/azure-sdk-for-go/sdk/ai/azopenai v0.9.0/go.mod h1:Bb4vy1c7tXIqFrypNxCO7I5xlDSbpQiOWu/XvF5htP8=
+github.com/Azure/azure-sdk-for-go/sdk/azcore v1.21.0 h1:fou+2+WFTib47nS+nz/ozhEBnvU96bKHy6LjRsY4E28=
+github.com/Azure/azure-sdk-for-go/sdk/azcore v1.21.0/go.mod h1:t76Ruy8AHvUAC8GfMWJMa0ElSbuIcO03NLpynfbgsPA=
+github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2 h1:9iefClla7iYpfYWdzPCRDozdmndjTm8DXdpCzPajMgA=
+github.com/Azure/azure-sdk-for-go/sdk/internal v1.11.2/go.mod h1:XtLgD3ZD34DAaVIIAyG3objl5DynM3CQ/vMcbBNJZGI=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/anthropics/anthropic-sdk-go v1.26.0 h1:oUTzFaUpAevfuELAP1sjL6CQJ9HHAfT7CoSYSac11PY=
 github.com/anthropics/anthropic-sdk-go v1.26.0/go.mod h1:qUKmaW+uuPB64iy1l+4kOSvaLqPXnHTTBKH6RVZ7q5Q=
@@ -55,6 +61,8 @@ github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aN
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
 github.com/openai/openai-go v1.12.0 h1:NBQCnXzqOTv5wsgNC36PrFEiskGfO5wccfCWDo9S1U0=
 github.com/openai/openai-go v1.12.0/go.mod h1:g461MYGXEXBVdV5SaR/5tNzNbSfwTBBefwc+LlDCK0Y=
+github.com/openai/openai-go/v3 v3.2.0 h1:2AbqFUCsoW2pm/2pUtPRuwK89dnoGHaQokzWsfoQO/U=
+github.com/openai/openai-go/v3 v3.2.0/go.mod h1:UOpNxkqC9OdNXNUfpNByKOtB4jAL0EssQXq5p8gO0Xs=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
@@ -66,6 +74,7 @@ github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
 github.com/tidwall/gjson v1.14.2/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
 github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
 github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
@@ -82,6 +91,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.40.0 h1:r4x+VvoG5Fm+eJcxMaY8CQM7Lb0l1lsmjGBQ6s8BfKM=
 golang.org/x/crypto v0.40.0/go.mod h1:Qr1vMER5WyS2dfPHAlsOj01wgLbsyWtFn/aY+5+ZdxY=
+golang.org/x/crypto v0.47.0 h1:V6e3FRj+n4dbpw86FJ8Fv7XVOql7TEwpHapKoMJ/GO8=
+golang.org/x/crypto v0.47.0/go.mod h1:ff3Y9VzzKbwSSEzWqJsJVBnWmRwRSHt/6Op5n9bQc4A=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20190227174305-5b3e6a55c961/go.mod h1:wehouNa3lNwaWXcvxsM5YxQ5yQlVC4a0KAMCusXpPoU=
@@ -94,22 +105,30 @@ golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20201110031124-69a78807bb2b/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.41.0 h1:vBTly1HeNPEn3wtREYfy4GZ/NECgw2Cnl+nK6Nz3uvw=
 golang.org/x/net v0.41.0/go.mod h1:B/K4NNqkfmg07DQYrbwvSluqCJOOXwUjeb/5lOisjbA=
+golang.org/x/net v0.49.0 h1:eeHFmOGUTtaaPSGNmjBKpbng9MulQsJURQUAfUwY++o=
+golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.16.0 h1:ycBJEhp9p4vXvUZNszeOq0kGTPghopOL8q0fq3vstxw=
 golang.org/x/sync v0.16.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
+golang.org/x/sync v0.19.0 h1:vV+1eWNmZ5geRlYjzm2adRgW2/mcpevXNg50YZtPCE4=
+golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200930185726-fdedc70b468f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.34.0 h1:H5Y5sJ2L2JRdyv7ROF1he/lPdvFsd0mJHFw2ThKHxLA=
 golang.org/x/sys v0.34.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
+golang.org/x/sys v0.40.0 h1:DBZZqJ2Rkml6QMQsZywtnjnnGvHza6BTfYFWY9kjEWQ=
+golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.27.0 h1:4fGWRpyh641NLlecmyl4LOe6yDdfaYNrGb2zdfo4JV4=
 golang.org/x/text v0.27.0/go.mod h1:1D28KMCvyooCX9hBiosv5Tz/+YLxj0j7XhWjpSUF7CU=
+golang.org/x/text v0.33.0 h1:B3njUFyqtHDUI5jMn1YIr5B0IE2U0qck04r6d4KPAxE=
+golang.org/x/text v0.33.0/go.mod h1:LuMebE6+rBincTi9+xWTY8TztLzKHc/9C1uBCG27+q8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
diff --git a/internal/config/config.go b/internal/config/config.go
index c6c6ef0..eafdc44 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -28,9 +28,10 @@ type ServerConfig struct {
 
 // ProvidersConfig wraps supported provider settings.
 type ProvidersConfig struct {
-	Google    ProviderConfig `yaml:"google"`
-	Anthropic ProviderConfig `yaml:"anthropic"`
-	OpenAI    ProviderConfig `yaml:"openai"`
+	Google       ProviderConfig       `yaml:"google"`
+	Anthropic    ProviderConfig       `yaml:"anthropic"`
+	OpenAI       ProviderConfig       `yaml:"openai"`
+	AzureOpenAI  AzureOpenAIConfig    `yaml:"azureopenai"`
 }
 
 // ProviderConfig contains shared provider configuration fields.
@@ -40,6 +41,14 @@ type ProviderConfig struct {
 	Endpoint string `yaml:"endpoint"`
 }
 
+// AzureOpenAIConfig contains Azure-specific settings.
+type AzureOpenAIConfig struct {
+	APIKey       string `yaml:"api_key"`
+	Endpoint     string `yaml:"endpoint"`
+	DeploymentID string `yaml:"deployment_id"`
+	APIVersion   string `yaml:"api_version"`
+}
+
 // Load reads and parses a YAML configuration file and applies env overrides.
 func Load(path string) (*Config, error) {
 	data, err := os.ReadFile(path)
@@ -60,6 +69,20 @@ func (cfg *Config) applyEnvOverrides() {
 	overrideAPIKey(&cfg.Providers.Google, "GOOGLE_API_KEY")
 	overrideAPIKey(&cfg.Providers.Anthropic, "ANTHROPIC_API_KEY")
 	overrideAPIKey(&cfg.Providers.OpenAI, "OPENAI_API_KEY")
+	
+	// Azure OpenAI overrides
+	if v := os.Getenv("AZURE_OPENAI_API_KEY"); v != "" {
+		cfg.Providers.AzureOpenAI.APIKey = v
+	}
+	if v := os.Getenv("AZURE_OPENAI_ENDPOINT"); v != "" {
+		cfg.Providers.AzureOpenAI.Endpoint = v
+	}
+	if v := os.Getenv("AZURE_OPENAI_DEPLOYMENT_ID"); v != "" {
+		cfg.Providers.AzureOpenAI.DeploymentID = v
+	}
+	if v := os.Getenv("AZURE_OPENAI_API_VERSION"); v != "" {
+		cfg.Providers.AzureOpenAI.APIVersion = v
+	}
 }
 
 func overrideAPIKey(cfg *ProviderConfig, envKey string) {
diff --git a/internal/providers/openai/openai.go b/internal/providers/openai/openai.go
index 42018b6..ac55a01 100644
--- a/internal/providers/openai/openai.go
+++ b/internal/providers/openai/openai.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/openai/openai-go"
+	"github.com/openai/openai-go/azure"
 	"github.com/openai/openai-go/option"
 
 	"github.com/yourusername/go-llm-gateway/internal/api"
@@ -15,12 +16,14 @@ import (
 const Name = "openai"
 
 // Provider implements the OpenAI SDK integration.
+// It supports both direct OpenAI API and Azure-hosted endpoints.
 type Provider struct {
 	cfg    config.ProviderConfig
 	client *openai.Client
+	azure  bool
 }
 
-// New constructs a Provider from configuration.
+// New constructs a Provider for the direct OpenAI API.
 func New(cfg config.ProviderConfig) *Provider {
 	var client *openai.Client
 	if cfg.APIKey != "" {
@@ -33,6 +36,32 @@ func New(cfg config.ProviderConfig) *Provider {
 	}
 }
 
+// NewAzure constructs a Provider targeting Azure OpenAI.
+// Azure OpenAI uses the OpenAI SDK with the azure subpackage for proper
+// endpoint routing, api-version query parameter, and API key header.
+func NewAzure(azureCfg config.AzureOpenAIConfig) *Provider {
+	var client *openai.Client
+	if azureCfg.APIKey != "" && azureCfg.Endpoint != "" {
+		apiVersion := azureCfg.APIVersion
+		if apiVersion == "" {
+			apiVersion = "2024-12-01-preview"
+		}
+		c := openai.NewClient(
+			azure.WithEndpoint(azureCfg.Endpoint, apiVersion),
+			azure.WithAPIKey(azureCfg.APIKey),
+		)
+		client = &c
+	}
+	return &Provider{
+		cfg: config.ProviderConfig{
+			APIKey: azureCfg.APIKey,
+			Model:  azureCfg.DeploymentID,
+		},
+		client: client,
+		azure:  true,
+	}
+}
+
 // Name returns the provider identifier.
 func (p *Provider) Name() string { return Name }
 
diff --git a/internal/providers/providers.go b/internal/providers/providers.go
index 6b9f607..f8a6f29 100644
--- a/internal/providers/providers.go
+++ b/internal/providers/providers.go
@@ -34,7 +34,9 @@ func NewRegistry(cfg config.ProvidersConfig) (*Registry, error) {
 	if cfg.Anthropic.APIKey != "" {
 		reg.providers[anthropicprovider.Name] = anthropicprovider.New(cfg.Anthropic)
 	}
-	if cfg.OpenAI.APIKey != "" {
+	if cfg.AzureOpenAI.APIKey != "" && cfg.AzureOpenAI.Endpoint != "" {
+		reg.providers[openaiprovider.Name] = openaiprovider.NewAzure(cfg.AzureOpenAI)
+	} else if cfg.OpenAI.APIKey != "" {
 		reg.providers[openaiprovider.Name] = openaiprovider.New(cfg.OpenAI)
 	}
 
@@ -55,7 +57,7 @@ func (r *Registry) Get(name string) (Provider, bool) {
 func (r *Registry) Default(model string) (Provider, error) {
 	if model != "" {
 		switch {
-		case strings.HasPrefix(model, "gpt") || strings.HasPrefix(model, "o1"):
+		case strings.HasPrefix(model, "gpt") || strings.HasPrefix(model, "o1") || strings.HasPrefix(model, "o3"):
 			if p, ok := r.providers[openaiprovider.Name]; ok {
 				return p, nil
 			}