diff --git a/genkit-tools/cli/src/commands/start.ts b/genkit-tools/cli/src/commands/start.ts
index 5d6980e957..226368ac62 100644
--- a/genkit-tools/cli/src/commands/start.ts
+++ b/genkit-tools/cli/src/commands/start.ts
@@ -24,6 +24,7 @@ interface StartOptions {
   headless?: boolean;
   port: string;
   attach?: string;
+  open?: boolean;
 }
 
 /** Command to start GenKit server, optionally without static file serving */
@@ -35,6 +36,7 @@ export const start = new Command('start')
     false
   )
   .option('-p, --port <number>', 'Port to serve on. Default is 4000', '4000')
+  .option('-o, --open', 'Open the browser with the Developer UI')
   .option(
     '-a, --attach <number>',
     'Externally running dev process address to attach to'
@@ -57,5 +59,5 @@ export const start = new Command('start')
     } else {
       await runner.start();
     }
-    return startServer(runner, options.headless ?? false, port);
+    return startServer(runner, options.headless ?? false, port, !!options.open);
   });
diff --git a/genkit-tools/common/src/server/server.ts b/genkit-tools/common/src/server/server.ts
index 7ff0ea0f7d..b4715936e5 100644
--- a/genkit-tools/common/src/server/server.ts
+++ b/genkit-tools/common/src/server/server.ts
@@ -45,7 +45,8 @@ const API_BASE_PATH = '/api';
 export function startServer(
   runner: Runner,
   headless: boolean,
-  port: number
+  port: number,
+  openBrowser: boolean
 ): Promise<void> {
   let serverEnder: (() => void) | undefined = undefined;
   const enderPromise = new Promise<void>((resolver) => {
@@ -133,7 +134,9 @@ export function startServer(
         .waitUntilHealthy()
         .then(() => {
           logger.info(`${clc.green(clc.bold('Genkit Tools UI:'))} ${uiUrl}`);
-          open(uiUrl);
+          if (openBrowser) {
+            open(uiUrl);
+          }
         })
         .catch((e) => {
           logger.error(e.message);