diff --git a/.env.example b/.env.example
index bfadfd442..daea3cf89 100644
--- a/.env.example
+++ b/.env.example
@@ -11,6 +11,9 @@ MCP_REGISTRY_DATABASE_URL=postgres://username:password@localhost:5432/mcp-regist
 # For offline development, use: data/seed.json
 MCP_REGISTRY_SEED_FROM=https://registry.modelcontextprotocol.io/v0/servers
 
+# Custom MCP Registry URL for self-hosted instances (optional)
+MCP_REGISTRY_CUSTOM_MCP_REGISTRY_URL=https://your-registry-url.com
+
 # GitHub OAuth configuration
 # These creds are for local development with the 'MCP Registry Login (Local)' GitHub App
 # They don't provide any real privileged access, hence why it's okay that they're here
diff --git a/internal/api/handlers/v0/ui.go b/internal/api/handlers/v0/ui.go
index 32aadd4e2..769553fc6 100644
--- a/internal/api/handlers/v0/ui.go
+++ b/internal/api/handlers/v0/ui.go
@@ -2,12 +2,39 @@ package v0
 
 import (
 	_ "embed"
+	"encoding/json"
+	"strings"
 )
 
 //go:embed ui_index.html
 var embedUI string
 
-// GetUIHTML returns the embedded HTML for the UI
-func GetUIHTML() string {
-	return embedUI
+const (
+	defaultAPIBasePlaceholder    = "PLACEHOLDER"
+	defaultAPIBaseValueKey       = "__DEFAULT_API_BASE_VALUE__"
+	defaultAPIBasePlaceholderKey = "__DEFAULT_API_BASE_PLACEHOLDER__"
+)
+
+// GetUIHTML returns the embedded HTML for the UI with injected API base URL configuration.
+// The defaultBaseURL is injected into the JavaScript context to allow the frontend to
+// access a custom registry URL set via environment variable. If no custom URL is provided,
+// the frontend will fall back to the default production registry.
+func GetUIHTML(defaultBaseURL string) string {
+	// Marshal the URL to get a JSON-encoded string for safe JavaScript injection
+	jsonEncoded, err := json.Marshal(defaultBaseURL)
+	if err != nil {
+		// Fallback to empty string if marshaling fails (should be very rare for strings)
+		jsonEncoded = []byte(`""`)
+	}
+
+	// Trim the surrounding quotes from JSON encoding to get the raw URL value
+	value := strings.Trim(string(jsonEncoded), `"`)
+
+	// Inject the actual URL value into the UI
+	html := strings.ReplaceAll(embedUI, defaultAPIBaseValueKey, value)
+
+	// Inject the placeholder sentinel value for frontend comparison logic
+	html = strings.ReplaceAll(html, defaultAPIBasePlaceholderKey, defaultAPIBasePlaceholder)
+
+	return html
 }
diff --git a/internal/api/handlers/v0/ui_index.html b/internal/api/handlers/v0/ui_index.html
index 38bac7f7b..b3e77c68d 100644
--- a/internal/api/handlers/v0/ui_index.html
+++ b/internal/api/handlers/v0/ui_index.html
@@ -138,6 +138,9 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
     </div>
 
     <script>
+        window.__DEFAULT_API_BASE__ = "__DEFAULT_API_BASE_VALUE__";
+        window.__DEFAULT_API_BASE_PLACEHOLDER__ = "__DEFAULT_API_BASE_PLACEHOLDER__";
+
         let servers = [];
         let cursorHistory = [];
         let currentCursor = null;
@@ -145,9 +148,21 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
         let searchTimeout = null;
         let baseUrl = '';
 
+        function getInjectedDefaultBase() {
+            return (window.__DEFAULT_API_BASE__ && window.__DEFAULT_API_BASE__ !== window.__DEFAULT_API_BASE_PLACEHOLDER__)
+                ? window.__DEFAULT_API_BASE__
+                : '';
+        }
+
+        function normalizeBaseUrl(url) {
+            const trimmed = (url || '').trim();
+            return trimmed.endsWith('/') ? trimmed.slice(0, -1) : trimmed;
+        }
+
         // Get base URL based on selection
         function getBaseUrl() {
-            const selection = localStorage.getItem('baseUrl') || 'local';
+            const defaultApiBase = getInjectedDefaultBase();
+            const selection = (defaultApiBase && !localStorage.getItem('customUrl')) ? 'custom' : (localStorage.getItem('baseUrl') || 'prod');
             const customUrl = localStorage.getItem('customUrl') || '';
 
             switch (selection) {
@@ -158,7 +173,7 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
                 case 'local':
                     return '';
                 case 'custom':
-                    return customUrl;
+                    return customUrl || defaultApiBase;
                 default:
                     return '';
             }
@@ -166,7 +181,8 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
 
         // Get server display name
         function getServerName() {
-            const selection = localStorage.getItem('baseUrl') || 'local';
+            const defaultApiBase = getInjectedDefaultBase();
+            const selection = (defaultApiBase && !localStorage.getItem('customUrl')) ? 'custom' : (localStorage.getItem('baseUrl') || 'prod');
             const customUrl = localStorage.getItem('customUrl') || '';
 
             switch (selection) {
@@ -184,6 +200,15 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
         }
 
         // Initialize base URL and server name
+        if (!localStorage.getItem('baseUrl')) {
+            const defaultApiBase = getInjectedDefaultBase();
+            if (defaultApiBase) {
+                localStorage.setItem('baseUrl', 'custom');
+                localStorage.setItem('customUrl', normalizeBaseUrl(defaultApiBase));
+            } else {
+                localStorage.setItem('baseUrl', 'prod');
+            }
+        }
         baseUrl = getBaseUrl();
         document.getElementById('server-name').textContent = getServerName();
 
@@ -220,9 +245,11 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
 
         // Debug modal handlers
         document.getElementById('debug-btn').addEventListener('click', () => {
-            const selection = localStorage.getItem('baseUrl') || 'prod';
+            const defaultApiBase = getInjectedDefaultBase();
+            const selection = (defaultApiBase && !localStorage.getItem('customUrl')) ? 'custom' : (localStorage.getItem('baseUrl') || 'prod');
             document.querySelector(`input[name="baseUrl"][value="${selection}"]`).checked = true;
-            document.getElementById('custom-url').value = localStorage.getItem('customUrl') || '';
+            const customUrlValue = localStorage.getItem('customUrl') || (selection === 'custom' ? defaultApiBase : '');
+            document.getElementById('custom-url').value = customUrlValue;
             document.getElementById('custom-url').disabled = selection !== 'custom';
             document.getElementById('debug-modal').classList.remove('hidden');
         });
@@ -233,7 +260,7 @@ <h3 class="text-lg font-semibold mb-4">API Base URL</h3>
 
         document.getElementById('debug-apply').addEventListener('click', () => {
             const selection = document.querySelector('input[name="baseUrl"]:checked').value;
-            const customUrl = document.getElementById('custom-url').value;
+            const customUrl = normalizeBaseUrl(document.getElementById('custom-url').value);
             localStorage.setItem('baseUrl', selection);
             localStorage.setItem('customUrl', customUrl);
             location.reload();
diff --git a/internal/api/router/router.go b/internal/api/router/router.go
index d951e6028..419df691a 100644
--- a/internal/api/router/router.go
+++ b/internal/api/router/router.go
@@ -189,7 +189,7 @@ func NewHumaAPI(cfg *config.Config, registry service.RegistryService, mux *http.
 		if r.URL.Path == "/" {
 			// Serve UI at root
 			w.Header().Set("Content-Type", "text/html; charset=utf-8")
-			_, err := w.Write([]byte(v0.GetUIHTML()))
+			_, err := w.Write([]byte(v0.GetUIHTML(cfg.CustomMCPRegistryURL)))
 			if err != nil {
 				http.Error(w, "Failed to write response", http.StatusInternalServerError)
 			}
diff --git a/internal/config/config.go b/internal/config/config.go
index 60e9a067b..e7cc76fc2 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -11,6 +11,7 @@ type Config struct {
 	DatabaseURL              string `env:"DATABASE_URL" envDefault:"postgres://localhost:5432/mcp-registry?sslmode=disable"`
 	SeedFrom                 string `env:"SEED_FROM" envDefault:""`
 	Version                  string `env:"VERSION" envDefault:"dev"`
+	CustomMCPRegistryURL     string `env:"CUSTOM_MCP_REGISTRY_URL" envDefault:""`
 	GithubClientID           string `env:"GITHUB_CLIENT_ID" envDefault:""`
 	GithubClientSecret       string `env:"GITHUB_CLIENT_SECRET" envDefault:""`
 	JWTPrivateKey            string `env:"JWT_PRIVATE_KEY" envDefault:""`