diff --git a/setup.py b/setup.py
index c07920520..25f503f8d 100644
--- a/setup.py
+++ b/setup.py
@@ -36,6 +36,12 @@ To create the package for pypi.
 from io import open
 from setuptools import find_packages, setup
 
+
+extras = {
+    'serving': ['uvicorn', 'fastapi']
+}
+extras['all'] = [package for package in extras.values()]
+
 setup(
     name="transformers",
     version="2.2.1",
@@ -61,6 +67,10 @@ setup(
         "transformers=transformers.__main__:main",
       ]
     },
+    extras_require=extras,
+    scripts=[
+        'transformers-cli'
+    ],
     # python_requires='>=3.5.0',
     tests_require=['pytest'],
     classifiers=[
diff --git a/transformers-cli b/transformers-cli
new file mode 100644
index 000000000..ef00d15aa
--- /dev/null
+++ b/transformers-cli
@@ -0,0 +1,23 @@
+#!/usr/bin/env python
+from argparse import ArgumentParser
+
+from transformers.commands.user import UserCommands
+
+
+if __name__ == '__main__':
+    parser = ArgumentParser(description='Transformers CLI tool', usage='transformers-cli <command> [<args>]')
+    commands_parser = parser.add_subparsers(help='transformers-cli command helpers')
+
+    # Register commands
+    UserCommands.register_subcommand(commands_parser)
+
+    # Let's go
+    args = parser.parse_args()
+
+    if not hasattr(args, 'func'):
+        parser.print_help()
+        exit(1)
+
+    # Run
+    service = args.func(args)
+    service.run()
diff --git a/transformers/commands/__init__.py b/transformers/commands/__init__.py
new file mode 100644
index 000000000..bbdd5655f
--- /dev/null
+++ b/transformers/commands/__init__.py
@@ -0,0 +1,12 @@
+from abc import ABC, abstractmethod
+from argparse import ArgumentParser
+
+class BaseTransformersCLICommand(ABC):
+    @staticmethod
+    @abstractmethod
+    def register_subcommand(parser: ArgumentParser):
+        raise NotImplementedError()
+
+    @abstractmethod
+    def run(self):
+        raise NotImplementedError()
diff --git a/transformers/commands/user.py b/transformers/commands/user.py
new file mode 100644
index 000000000..4b826f4dc
--- /dev/null
+++ b/transformers/commands/user.py
@@ -0,0 +1,122 @@
+from argparse import ArgumentParser
+from getpass import getpass
+import os
+
+from transformers.commands import BaseTransformersCLICommand
+from transformers.hf_api import HfApi, HfFolder, HTTPError
+
+
+class UserCommands(BaseTransformersCLICommand):
+    @staticmethod
+    def register_subcommand(parser: ArgumentParser):
+        login_parser = parser.add_parser('login')
+        login_parser.set_defaults(func=lambda args: LoginCommand(args))
+        whoami_parser = parser.add_parser('whoami')
+        whoami_parser.set_defaults(func=lambda args: WhoamiCommand(args))
+        logout_parser = parser.add_parser('logout')
+        logout_parser.set_defaults(func=lambda args: LogoutCommand(args))
+        list_parser = parser.add_parser('ls')
+        list_parser.set_defaults(func=lambda args: ListObjsCommand(args))
+        # upload
+        upload_parser = parser.add_parser('upload')
+        upload_parser.add_argument('file', type=str, help='Local filepath of the file to upload.')
+        upload_parser.add_argument('--filename', type=str, default=None, help='Optional: override object filename on S3.')
+        upload_parser.set_defaults(func=lambda args: UploadCommand(args))
+
+
+
+class BaseUserCommand:
+    def __init__(self, args):
+        self.args = args
+        self._api = HfApi()
+
+
+class LoginCommand(BaseUserCommand):
+    def run(self):
+        print("""
+        _|    _|  _|    _|    _|_|_|    _|_|_|  _|_|_|  _|      _|    _|_|_|      _|_|_|_|    _|_|      _|_|_|  _|_|_|_|  
+        _|    _|  _|    _|  _|        _|          _|    _|_|    _|  _|            _|        _|    _|  _|        _|        
+        _|_|_|_|  _|    _|  _|  _|_|  _|  _|_|    _|    _|  _|  _|  _|  _|_|      _|_|_|    _|_|_|_|  _|        _|_|_|    
+        _|    _|  _|    _|  _|    _|  _|    _|    _|    _|    _|_|  _|    _|      _|        _|    _|  _|        _|        
+        _|    _|    _|_|      _|_|_|    _|_|_|  _|_|_|  _|      _|    _|_|_|      _|        _|    _|    _|_|_|  _|_|_|_|  
+
+        """)
+        username = input("Username: ")
+        password = getpass()
+        try:
+            token = self._api.login(username, password)
+        except HTTPError as e:
+            # probably invalid credentials, display error message.
+            print(e)
+            exit(1)
+        HfFolder.save_token(token)
+        print("Login successful")
+        print("Your token:", token, "\n")
+        print("Your token has been saved to", HfFolder.path_token)
+
+
+class WhoamiCommand(BaseUserCommand):
+    def run(self):
+        token = HfFolder.get_token()
+        if token is None:
+            print("Not logged in")
+            exit()
+        try:
+            user = self._api.whoami(token)
+            print(user)
+        except HTTPError as e:
+            print(e)
+
+
+class LogoutCommand(BaseUserCommand):
+    def run(self):
+        token = HfFolder.get_token()
+        if token is None:
+            print("Not logged in")
+            exit()
+        HfFolder.delete_token()
+        self._api.logout(token)
+        print("Successfully logged out.")
+
+
+class ListObjsCommand(BaseUserCommand):
+    def run(self):
+        token = HfFolder.get_token()
+        if token is None:
+            print("Not logged in")
+            exit(1)
+        try:
+            objs = self._api.list_objs(token)
+        except HTTPError as e:
+            print(e)
+            exit(1)
+        if len(objs) == 0:
+            print("No shared file yet")
+        for obj in objs:
+            print(
+                obj.filename,
+                obj.LastModified,
+                obj.ETag,
+                obj.Size
+            )
+
+
+class UploadCommand(BaseUserCommand):
+    def run(self):
+        token = HfFolder.get_token()
+        if token is None:
+            print("Not logged in")
+            exit(1)
+        filepath = os.path.join(os.getcwd(), self.args.file)
+        filename = self.args.filename if self.args.filename is not None else os.path.basename(filepath)
+        print("About to upload file {} to S3 under filename {}".format(filepath, filename))
+        choice = input("Proceed? [Y/n] ").lower()
+        if not(choice == "" or choice == "y" or choice == "yes"):
+            print("Abort")
+            exit()
+        print("Uploading...")
+        access_url = self._api.presign_and_upload(
+            token=token, filename=filename, filepath=filepath
+        )
+        print("Your file now lives at:")
+        print(access_url)
diff --git a/transformers/hf_api.py b/transformers/hf_api.py
new file mode 100644
index 000000000..238762ebf
--- /dev/null
+++ b/transformers/hf_api.py
@@ -0,0 +1,152 @@
+# coding=utf-8
+# Copyright 2019-present, the HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import, division, print_function
+
+from typing import List, NamedTuple
+import os
+from os.path import expanduser
+
+import requests
+from requests.exceptions import HTTPError
+
+ENDPOINT = "https://huggingface.co"
+
+class S3Obj:
+    def __init__(self, filename: str, LastModified: str, ETag: str, Size: int):
+        self.filename = filename
+        self.LastModified = LastModified
+        self.ETag = ETag
+        self.Size = Size
+
+
+class PresignedUrl(NamedTuple):
+    write: str
+    access: str
+
+
+class HfApi:
+    def __init__(self, endpoint=None):
+        self.endpoint = endpoint if endpoint is not None else ENDPOINT
+
+    def login(self, username: str, password: str) -> str:
+        """
+        Call HF API to sign in a user and get a token if credentials are valid.
+
+        Outputs:
+            token if credentials are valid
+
+        Throws:
+            requests.exceptions.HTTPError if credentials are invalid
+        """
+        path = "{}/api/login".format(self.endpoint)
+        r = requests.post(path, json={"username": username, "password": password})
+        r.raise_for_status()
+        d = r.json()
+        return d["token"]
+
+    def whoami(self, token: str) -> str:
+        """
+        Call HF API to know "whoami"
+        """
+        path = "{}/api/whoami".format(self.endpoint)
+        r = requests.get(path, headers={"authorization": "Bearer {}".format(token)})
+        r.raise_for_status()
+        d = r.json()
+        return d["user"]
+
+    def logout(self, token: str):
+        """
+        Call HF API to log out.
+        """
+        path = "{}/api/logout".format(self.endpoint)
+        r = requests.post(path, headers={"authorization": "Bearer {}".format(token)})
+        r.raise_for_status()
+
+    def presign(self, token: str, filename: str) -> PresignedUrl:
+        """
+        Call HF API to get a presigned url to upload `filename` to S3.
+        """
+        path = "{}/api/presign".format(self.endpoint)
+        r = requests.post(
+            path,
+            headers={"authorization": "Bearer {}".format(token)},
+            json={"filename": filename},
+        )
+        r.raise_for_status()
+        d = r.json()
+        return PresignedUrl(**d)
+
+    def presign_and_upload(self, token: str, filename: str, filepath: str) -> str:
+        """
+        Get a presigned url, then upload file to S3.
+
+        Outputs:
+            url: Read-only url for the stored file on S3.
+        """
+        urls = self.presign(token, filename=filename)
+        # streaming upload:
+        # https://2.python-requests.org/en/master/user/advanced/#streaming-uploads
+        with open(filepath, "rb") as f:
+            r = requests.put(urls.write, data=f)
+            r.raise_for_status()
+        return urls.access
+
+    def list_objs(self, token: str) -> List[S3Obj]:
+        """
+        Call HF API to list all stored files for user.
+        """
+        path = "{}/api/listObjs".format(self.endpoint)
+        r = requests.get(path, headers={"authorization": "Bearer {}".format(token)})
+        r.raise_for_status()
+        d = r.json()
+        return [S3Obj(**x) for x in d]
+
+
+
+
+
+class HfFolder:
+    path_token = expanduser("~/.huggingface/token")
+
+    @classmethod
+    def save_token(cls, token: str):
+        """
+        Save token, creating folder as needed.
+        """
+        os.makedirs(os.path.dirname(cls.path_token), exist_ok=True)
+        with open(cls.path_token, 'w+') as f:
+            f.write(token)
+
+    @classmethod
+    def get_token(cls):
+        """
+        Get token or None if not existent.
+        """
+        try:
+            with open(cls.path_token, 'r') as f:
+                return f.read()
+        except FileNotFoundError:
+            return None
+
+    @classmethod
+    def delete_token(cls):
+        """
+        Delete token.
+        Do not fail if token does not exist.
+        """
+        try:
+            os.remove(cls.path_token)
+        except:
+            return
diff --git a/transformers/tests/hf_api_test.py b/transformers/tests/hf_api_test.py
new file mode 100644
index 000000000..59822344b
--- /dev/null
+++ b/transformers/tests/hf_api_test.py
@@ -0,0 +1,94 @@
+# coding=utf-8
+# Copyright 2019-present, the HuggingFace Inc. team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from __future__ import absolute_import, division, print_function
+
+import os
+import time
+import unittest
+
+from transformers.hf_api import HfApi, S3Obj, PresignedUrl, HfFolder, HTTPError
+
+USER = "__DUMMY_TRANSFORMERS_USER__"
+PASS = "__DUMMY_TRANSFORMERS_PASS__"
+FILE_KEY = "Test-{}.txt".format(int(time.time()))
+FILE_PATH = os.path.join(
+    os.path.dirname(os.path.abspath(__file__)), "fixtures/input.txt"
+)
+
+
+
+class HfApiCommonTest(unittest.TestCase):
+    _api = HfApi(endpoint="https://moon-staging.huggingface.co")
+
+
+class HfApiLoginTest(HfApiCommonTest):
+    def test_login_invalid(self):
+        with self.assertRaises(HTTPError):
+            self._api.login(username=USER, password="fake")
+
+    def test_login_valid(self):
+        token = self._api.login(username=USER, password=PASS)
+        self.assertIsInstance(token, str)
+
+
+class HfApiEndpointsTest(HfApiCommonTest):
+    @classmethod
+    def setUpClass(cls):
+        """
+        Share this valid token in all tests below.
+        """
+        cls._token = cls._api.login(username=USER, password=PASS)
+
+    def test_whoami(self):
+        user = self._api.whoami(token=self._token)
+        self.assertEqual(user, USER)
+
+    def test_presign(self):
+        url = self._api.presign(token=self._token, filename=FILE_KEY)
+        self.assertIsInstance(url, PresignedUrl)
+
+    def test_presign_and_upload(self):
+        access_url = self._api.presign_and_upload(
+            token=self._token, filename=FILE_KEY, filepath=FILE_PATH
+        )
+        self.assertIsInstance(access_url, str)
+
+    def test_list_objs(self):
+        objs = self._api.list_objs(token=self._token)
+        o = objs[-1]
+        self.assertIsInstance(o, S3Obj)
+
+
+
+class HfFolderTest(unittest.TestCase):
+    def test_token_workflow(self):
+        """
+        Test the whole token save/get/delete workflow,
+        with the desired behavior with respect to non-existent tokens.
+        """
+        token = "token-{}".format(int(time.time()))
+        HfFolder.save_token(token)
+        self.assertEqual(
+            HfFolder.get_token(),
+            token
+        )
+        HfFolder.delete_token()
+        HfFolder.delete_token()
+        # ^^ not an error, we test that the
+        # second call does not fail.
+        self.assertEqual(
+            HfFolder.get_token(),
+            None
+        )