diff --git a/packages/api/src/API.ts b/packages/api/src/API.ts
index e8ce30117..d6812d302 100644
--- a/packages/api/src/API.ts
+++ b/packages/api/src/API.ts
@@ -322,7 +322,7 @@ async function setupPage(page: Page, options: APIOptions = {}): Promise<void> {
     await page.emulate(config.emulateDevice);
   }
 
-  if (config.defaultUserAgent) {
+  if (config.defaultUserAgent && config.defaultUserAgent !== 'default') {
     await page.setUserAgent(config.defaultUserAgent);
   }
 
diff --git a/packages/cli/src/commands/RunMeasureCommand.ts b/packages/cli/src/commands/RunMeasureCommand.ts
index 1835b1e9c..eba41989e 100644
--- a/packages/cli/src/commands/RunMeasureCommand.ts
+++ b/packages/cli/src/commands/RunMeasureCommand.ts
@@ -27,6 +27,7 @@ import RunningModeOption from '../options/e2e/RunningModeOption';
 import RemoteBrowserDebugOption from '../options/e2e/RemoteBrowserDebugOption';
 import ScenarioFileOption from '../options/e2e/ScenarioFileOption';
 import SetDeviceOption from '../options/e2e/SetDeviceOption';
+import SetUserAgentOption from '../options/e2e/SetUserAgentOption';
 import DisableXvfbOption from '../options/e2e/DisableXvfbOption';
 import NumberOfRunsOption from '../options/NumberOfRunsOption';
 import HeadfulBrowserOption from '../options/e2e/HeadfulBrowserOption';
@@ -68,6 +69,7 @@ export default class RunMeasureCommand extends BaseCommand {
       new RemoteBrowserDebugOption(),
       new ScenarioFileOption(),
       new SetDeviceOption(),
+      new SetUserAgentOption(),
       new DisableXvfbOption(),
     ];
   }
diff --git a/packages/cli/src/commands/WarmupAppCommand.ts b/packages/cli/src/commands/WarmupAppCommand.ts
index fa767da21..e4b14d38e 100644
--- a/packages/cli/src/commands/WarmupAppCommand.ts
+++ b/packages/cli/src/commands/WarmupAppCommand.ts
@@ -20,6 +20,7 @@ import RunningModeOption from '../options/e2e/RunningModeOption';
 import RemoteBrowserDebugOption from '../options/e2e/RemoteBrowserDebugOption';
 import ScenarioFileOption from '../options/e2e/ScenarioFileOption';
 import SetDeviceOption from '../options/e2e/SetDeviceOption';
+import SetUserAgentOption from '../options/e2e/SetUserAgentOption';
 import DisableXvfbOption from '../options/e2e/DisableXvfbOption';
 import SkipWarmupOption from '../options/e2e/SkipWarmupOption';
 import CheckXvfbSupportCommand from './snapshot/CheckXvfbSupportCommand';
@@ -54,6 +55,7 @@ export default class FBWarmupAppCommand extends BaseCommand {
       new RemoteBrowserDebugOption(),
       new ScenarioFileOption(),
       new SetDeviceOption(),
+      new SetUserAgentOption(),
       new DisableXvfbOption(),
       new SkipWarmupOption(),
     ];
diff --git a/packages/cli/src/commands/snapshot/TakeSnapshotCommand.ts b/packages/cli/src/commands/snapshot/TakeSnapshotCommand.ts
index 35301ce80..1de313835 100644
--- a/packages/cli/src/commands/snapshot/TakeSnapshotCommand.ts
+++ b/packages/cli/src/commands/snapshot/TakeSnapshotCommand.ts
@@ -30,6 +30,7 @@ import DisableXvfbOption from '../../options/e2e/DisableXvfbOption';
 import InitDirectoryCommand from '../InitDirectoryCommand';
 import CheckXvfbSupportCommand from './CheckXvfbSupportCommand';
 import HeadfulBrowserOption from '../../options/e2e/HeadfulBrowserOption';
+import SetUserAgentOption from '../../options/e2e/SetUserAgentOption';
 
 export default class TakeSnapshotCommand extends BaseCommand {
   getCommandName(): string {
@@ -71,6 +72,7 @@ export default class TakeSnapshotCommand extends BaseCommand {
       new RemoteBrowserDebugOption(),
       new ScenarioFileOption(),
       new SetDeviceOption(),
+      new SetUserAgentOption(),
       new DisableXvfbOption(),
     ];
   }
diff --git a/packages/cli/src/options/e2e/SetUserAgentOption.ts b/packages/cli/src/options/e2e/SetUserAgentOption.ts
new file mode 100644
index 000000000..a26f25b4b
--- /dev/null
+++ b/packages/cli/src/options/e2e/SetUserAgentOption.ts
@@ -0,0 +1,37 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ * @oncall ws_labs
+ */
+
+import type {ParsedArgs} from 'minimist';
+import type {MemLabConfig} from '@memlab/core';
+import {BaseOption} from '@memlab/core';
+
+export default class SetUserAgentOption extends BaseOption {
+  getOptionName(): string {
+    return 'user-agent';
+  }
+
+  getDescription(): string {
+    return (
+      'set the UserAgent string in browser (for E2E interaction), ' +
+      'otherwise it uses the default UserAgent from Chromium'
+    );
+  }
+
+  getExampleValues(): string[] {
+    return ['"Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_2)"'];
+  }
+
+  async parse(config: MemLabConfig, args: ParsedArgs): Promise<void> {
+    const optionName = this.getOptionName();
+    if (args[optionName]) {
+      config.defaultUserAgent = args[optionName];
+    }
+  }
+}
diff --git a/packages/core/src/lib/Constant.ts b/packages/core/src/lib/Constant.ts
index a6eddb18f..ec1a94023 100644
--- a/packages/core/src/lib/Constant.ts
+++ b/packages/core/src/lib/Constant.ts
@@ -18,9 +18,7 @@ const constants = {
   supportedBrowsers: Object.create(null),
   internalDir: 'fb-internal',
   monoRepoDir: '',
-  defaultUserAgent:
-    'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_2)' +
-    ' AppleWebKit/537.36 (KHTML, like Gecko) Chrome/83.0.4103.0 Safari/537.36',
+  defaultUserAgent: 'default',
   V8SyntheticRoots: [
     '(GC roots)',
     '(Internalized strings)',
diff --git a/website/docs/cli/CLI-commands.md b/website/docs/cli/CLI-commands.md
index 2494ae41e..06111cfa1 100644
--- a/website/docs/cli/CLI-commands.md
+++ b/website/docs/cli/CLI-commands.md
@@ -29,6 +29,7 @@ memlab run --scenario /tmp/test-scenario.js --work-dir /tmp/test-1/
  * **`--local-puppeteer`**: enable remote browser instance debugging via local puppeteer
  * **`--scenario`**: set file path loading test scenario
  * **`--device`**: set the device type to emulate
+ * **`--user-agent`**: set the UserAgent string in browser (for E2E interaction), otherwise it uses the default UserAgent from Chromium
  * **`--disable-xvfb`**: disable Xvfb (X virtual framebuffer) for simulating headful browser rendering
  * **`--leak-filter`**: specify a definition JS file for leak filter
  * **`--trace-object-size-above`**: objects with retained size (bytes) bigger than the threshold will be considered as leaks
@@ -440,6 +441,7 @@ memlab measure --scenario /tmp/test-scenario.js --work-dir /tmp/test-1/
  * **`--local-puppeteer`**: enable remote browser instance debugging via local puppeteer
  * **`--scenario`**: set file path loading test scenario
  * **`--device`**: set the device type to emulate
+ * **`--user-agent`**: set the UserAgent string in browser (for E2E interaction), otherwise it uses the default UserAgent from Chromium
  * **`--disable-xvfb`**: disable Xvfb (X virtual framebuffer) for simulating headful browser rendering
  * **`--work-dir`**: set the working directory of the current run
  * **`--help`**, **`-h`**: print helper text
@@ -470,6 +472,7 @@ memlab warmup --scenario /tmp/test-scenario.js
  * **`--local-puppeteer`**: enable remote browser instance debugging via local puppeteer
  * **`--scenario`**: set file path loading test scenario
  * **`--device`**: set the device type to emulate
+ * **`--user-agent`**: set the UserAgent string in browser (for E2E interaction), otherwise it uses the default UserAgent from Chromium
  * **`--disable-xvfb`**: disable Xvfb (X virtual framebuffer) for simulating headful browser rendering
  * **`--skip-warmup`**: skip warming up web server
  * **`--work-dir`**: set the working directory of the current run
@@ -538,6 +541,7 @@ memlab snapshot --scenario /tmp/test-scenario.js --work-dir /tmp/test-1/
  * **`--local-puppeteer`**: enable remote browser instance debugging via local puppeteer
  * **`--scenario`**: set file path loading test scenario
  * **`--device`**: set the device type to emulate
+ * **`--user-agent`**: set the UserAgent string in browser (for E2E interaction), otherwise it uses the default UserAgent from Chromium
  * **`--disable-xvfb`**: disable Xvfb (X virtual framebuffer) for simulating headful browser rendering
  * **`--work-dir`**: set the working directory of the current run
  * **`--help`**, **`-h`**: print helper text
@@ -563,6 +567,7 @@ memlab warmup-and-snapshot
  * **`--local-puppeteer`**: enable remote browser instance debugging via local puppeteer
  * **`--scenario`**: set file path loading test scenario
  * **`--device`**: set the device type to emulate
+ * **`--user-agent`**: set the UserAgent string in browser (for E2E interaction), otherwise it uses the default UserAgent from Chromium
  * **`--disable-xvfb`**: disable Xvfb (X virtual framebuffer) for simulating headful browser rendering
  * **`--skip-warmup`**: skip warming up web server
  * **`--full`**: take heap snapshot for every step in E2E interaction