diff --git a/snscrape/modules/twitter.py b/snscrape/modules/twitter.py
index ca45be8..a7461ed 100644
--- a/snscrape/modules/twitter.py
+++ b/snscrape/modules/twitter.py
@@ -434,7 +434,7 @@ class TwitterSearchScraper(TwitterAPIScraper):
 
 	def __init__(self, query, cursor = None, **kwargs):
 		super().__init__(baseUrl = 'https://twitter.com/search?' + urllib.parse.urlencode({'f': 'live', 'lang': 'en', 'q': query, 'src': 'spelling_expansion_revert_click'}), **kwargs)
-		self._query = query
+		self._query = query  # Note: may get replaced by subclasses when using user ID resolution
 		self._cursor = cursor
 
 	def _check_scroll_response(self, r):
@@ -498,16 +498,24 @@ class TwitterSearchScraper(TwitterAPIScraper):
 class TwitterUserScraper(TwitterSearchScraper):
 	name = 'twitter-user'
 
-	def __init__(self, username, **kwargs):
+	def __init__(self, username, isUserId, **kwargs):
 		if not self.is_valid_username(username):
 			raise ValueError('Invalid username')
 		super().__init__(f'from:{username}', **kwargs)
 		self._username = username
+		self._isUserId = isUserId
+		self._baseUrl = f'https://twitter.com/{self._username}' if not self._isUserId else f'https://twitter.com/i/user/{self._username}'
 
 	def _get_entity(self):
-		self._ensure_guest_token(f'https://twitter.com/{self._username}')
-		params = {'variables': json.dumps({'screen_name': self._username, 'withHighlightedLabel': True}, separators = (',', ':'))}
-		obj = self._get_api_data('https://api.twitter.com/graphql/-xfUfZsnR_zqjFd-IfrN5A/UserByScreenName', params = urllib.parse.urlencode(params, quote_via=urllib.parse.quote))
+		self._ensure_guest_token()
+		if not self._isUserId:
+			fieldName = 'screen_name'
+			endpoint = 'https://api.twitter.com/graphql/-xfUfZsnR_zqjFd-IfrN5A/UserByScreenName'
+		else:
+			fieldName = 'userId'
+			endpoint = 'https://twitter.com/i/api/graphql/WN6Hck-Pwm-YP0uxVj1oMQ/UserByRestIdWithoutResults'
+		params = {'variables': json.dumps({fieldName: self._username, 'withHighlightedLabel': True}, separators = (',', ':'))}
+		obj = self._get_api_data(endpoint, params = urllib.parse.urlencode(params, quote_via=urllib.parse.quote))
 		if not obj['data']:
 			return None
 		user = obj['data']['user']
@@ -536,9 +544,17 @@ class TwitterUserScraper(TwitterSearchScraper):
 			profileBannerUrl = user['legacy'].get('profile_banner_url'),
 		  )
 
+	def get_items(self):
+		if self._isUserId:
+			# Resolve user ID to username
+			self._username = self.entity.username
+			self._isUserId = False
+			self._query = f'from:{self._username}'
+		yield from super().get_items()
+
 	@staticmethod
 	def is_valid_username(s):
-		return 1 <= len(s) <= 15 and s.strip(string.ascii_letters + string.digits + '_') == ''
+		return (1 <= len(s) <= 15 and s.strip(string.ascii_letters + string.digits + '_') == '') or (s and s.strip(string.digits) == '')
 
 	@classmethod
 	def setup_parser(cls, subparser):
@@ -547,22 +563,22 @@ class TwitterUserScraper(TwitterSearchScraper):
 				return s
 			raise ValueError('Invalid username')
 
+		subparser.add_argument('--user-id', dest = 'isUserId', action = 'store_true', default = False, help = 'Use user ID instead of username')
 		subparser.add_argument('username', type = username, help = 'A Twitter username (without @)')
 
 	@classmethod
 	def from_args(cls, args):
-		return cls(args.username, retries = args.retries)
+		return cls(args.username, args.isUserId, retries = args.retries)
 
 
 class TwitterProfileScraper(TwitterUserScraper):
 	name = 'twitter-profile'
 
-	def __init__(self, *args, **kwargs):
-		super().__init__(*args, **kwargs)
-		self._baseUrl = f'https://twitter.com/{self._username}'
-
 	def get_items(self):
-		user = self.entity
+		if not self._isUserId:
+			userId = self.entity.id
+		else:
+			userId = self._username
 		params = {
 			'include_profile_interstitial_type': '1',
 			'include_blocking': '1',
@@ -586,7 +602,7 @@ class TwitterProfileScraper(TwitterUserScraper):
 			'send_error_codes': 'true',
 			'simple_quoted_tweets': 'true',
 			'include_tweet_replies': 'true',
-			'userId': user.id,
+			'userId': userId,
 			'count': '100',
 		}
 		paginationParams = params.copy()
@@ -594,7 +610,7 @@ class TwitterProfileScraper(TwitterUserScraper):
 		for d in (params, paginationParams):
 			d['ext'] = 'ext=mediaStats%2ChighlightedLabel'
 
-		for obj in self._iter_api_data(f'https://api.twitter.com/2/timeline/profile/{user.id}.json', params, paginationParams):
+		for obj in self._iter_api_data(f'https://api.twitter.com/2/timeline/profile/{userId}.json', params, paginationParams):
 			yield from self._instructions_to_tweets(obj)