diff --git a/Dockerfile b/Dockerfile
index eef9157..4965151 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -125,6 +125,7 @@ stdout_logfile=/dev/stdout
 stdout_logfile_maxbytes=0
 stderr_logfile=/dev/stderr
 stderr_logfile_maxbytes=0
+environment=API_ROOT_PATH="/api"
 EOF
 
 # Set permissions
diff --git a/backend/main.py b/backend/main.py
index fa0901f..f080e90 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -33,6 +33,12 @@ async def lifespan(app: FastAPI):
     print("👋 KV-Pix FastAPI Backend shutting down...")
 
 
+import os
+
+# Detect if running behind nginx proxy (via env var)
+# When behind nginx at /api, set root_path so Swagger knows correct URL prefix
+ROOT_PATH = os.getenv("API_ROOT_PATH", "")
+
 app = FastAPI(
     title="KV-Pix API",
     description="""
@@ -50,10 +56,11 @@ A powerful API for AI image generation using multiple providers.
 All generation endpoints require provider-specific cookies passed in the request body.
 See the Settings page in the web app for cookie configuration instructions.
     """,
-    version="1.0.0",
+    version="3.2.0",
     lifespan=lifespan,
     docs_url="/docs",
-    redoc_url="/redoc"
+    redoc_url="/redoc",
+    root_path=ROOT_PATH,
 )
 
 # CORS middleware - allow Next.js frontend