diff --git a/pyrogram/client/storage/file_storage.py b/pyrogram/client/storage/file_storage.py
new file mode 100644
index 00000000..ee5000c5
--- /dev/null
+++ b/pyrogram/client/storage/file_storage.py
@@ -0,0 +1,102 @@
+# Pyrogram - Telegram MTProto API Client Library for Python
+# Copyright (C) 2017-2019 Dan Tès <https://github.com/delivrance>
+#
+# This file is part of Pyrogram.
+#
+# Pyrogram is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Pyrogram is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
+
+import base64
+import json
+import logging
+import os
+import sqlite3
+from pathlib import Path
+from sqlite3 import DatabaseError
+from threading import Lock
+from typing import Union
+
+from .memory_storage import MemoryStorage
+
+log = logging.getLogger(__name__)
+
+
+class FileStorage(MemoryStorage):
+    FILE_EXTENSION = ".session"
+
+    def __init__(self, name: str, workdir: Path):
+        super().__init__(name)
+
+        self.workdir = workdir
+        self.database = workdir / (self.name + self.FILE_EXTENSION)
+        self.conn = None  # type: sqlite3.Connection
+        self.lock = Lock()
+
+    # noinspection PyAttributeOutsideInit
+    def migrate_from_json(self, path: Union[str, Path]):
+        log.warning("JSON session storage detected! Pyrogram will now convert it into an SQLite session storage...")
+
+        with open(path, encoding="utf-8") as f:
+            json_session = json.load(f)
+
+        os.remove(path)
+
+        self.open()
+
+        self.dc_id = json_session["dc_id"]
+        self.test_mode = json_session["test_mode"]
+        self.auth_key = base64.b64decode("".join(json_session["auth_key"]))
+        self.user_id = json_session["user_id"]
+        self.date = json_session.get("date", 0)
+        self.is_bot = json_session.get("is_bot", False)
+
+        peers_by_id = json_session.get("peers_by_id", {})
+        peers_by_phone = json_session.get("peers_by_phone", {})
+
+        peers = {}
+
+        for k, v in peers_by_id.items():
+            if v is None:
+                type_ = "group"
+            elif k.startswith("-100"):
+                type_ = "channel"
+            else:
+                type_ = "user"
+
+            peers[int(k)] = [int(k), int(v) if v is not None else None, type_, None, None]
+
+        for k, v in peers_by_phone.items():
+            peers[v][4] = k
+
+        # noinspection PyTypeChecker
+        self.update_peers(peers.values())
+
+        log.warning("Done! The session has been successfully converted from JSON to SQLite storage")
+
+    def open(self):
+        database_exists = os.path.isfile(self.database)
+
+        self.conn = sqlite3.connect(
+            str(self.database),
+            timeout=1,
+            check_same_thread=False
+        )
+
+        try:
+            if not database_exists:
+                self.create()
+
+            with self.conn:
+                self.conn.execute("VACUUM")
+        except DatabaseError:
+            self.migrate_from_json(self.database)
diff --git a/pyrogram/client/storage/memory_storage.py b/pyrogram/client/storage/memory_storage.py
new file mode 100644
index 00000000..7eb3a7d0
--- /dev/null
+++ b/pyrogram/client/storage/memory_storage.py
@@ -0,0 +1,241 @@
+# Pyrogram - Telegram MTProto API Client Library for Python
+# Copyright (C) 2017-2019 Dan Tès <https://github.com/delivrance>
+#
+# This file is part of Pyrogram.
+#
+# Pyrogram is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published
+# by the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# Pyrogram is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with Pyrogram.  If not, see <http://www.gnu.org/licenses/>.
+
+import base64
+import inspect
+import logging
+import sqlite3
+import struct
+import time
+from pathlib import Path
+from threading import Lock
+from typing import List, Tuple
+
+from pyrogram.api import types
+from pyrogram.client.storage.storage import Storage
+
+log = logging.getLogger(__name__)
+
+
+class MemoryStorage(Storage):
+    SCHEMA_VERSION = 1
+    USERNAME_TTL = 8 * 60 * 60
+    SESSION_STRING_FMT = ">B?256sI?"
+    SESSION_STRING_SIZE = 351
+
+    def __init__(self, name: str):
+        super().__init__(name)
+
+        self.conn = None  # type: sqlite3.Connection
+        self.lock = Lock()
+
+    def create(self):
+        with self.lock, self.conn:
+            with open(Path(__file__).parent / "schema.sql", "r") as schema:
+                self.conn.executescript(schema.read())
+
+            self.conn.execute(
+                "INSERT INTO version VALUES (?)",
+                (self.SCHEMA_VERSION,)
+            )
+
+            self.conn.execute(
+                "INSERT INTO sessions VALUES (?, ?, ?, ?, ?, ?)",
+                (1, None, None, 0, None, None)
+            )
+
+    def _import_session_string(self, string_session: str):
+        decoded = base64.urlsafe_b64decode(string_session + "=" * (-len(string_session) % 4))
+        return struct.unpack(self.SESSION_STRING_FMT, decoded)
+
+    def export_session_string(self):
+        packed = struct.pack(
+            self.SESSION_STRING_FMT,
+            self.dc_id,
+            self.test_mode,
+            self.auth_key,
+            self.user_id,
+            self.is_bot
+        )
+
+        return base64.urlsafe_b64encode(packed).decode().rstrip("=")
+
+    # noinspection PyAttributeOutsideInit
+    def open(self):
+        self.conn = sqlite3.connect(":memory:", check_same_thread=False)
+        self.create()
+
+        if self.name != ":memory:":
+            imported_session_string = self._import_session_string(self.name)
+
+            self.dc_id, self.test_mode, self.auth_key, self.user_id, self.is_bot = imported_session_string
+            self.date = 0
+
+        self.name = ":memory:" + str(self.user_id or "<unknown>")
+
+    # noinspection PyAttributeOutsideInit
+    def save(self):
+        self.date = int(time.time())
+
+        with self.lock:
+            self.conn.commit()
+
+    def close(self):
+        with self.lock:
+            self.conn.close()
+
+    def update_peers(self, peers: List[Tuple[int, int, str, str, str]]):
+        with self.lock:
+            self.conn.executemany(
+                "REPLACE INTO peers (id, access_hash, type, username, phone_number)"
+                "VALUES (?, ?, ?, ?, ?)",
+                peers
+            )
+
+    def clear_peers(self):
+        with self.lock, self.conn:
+            self.conn.execute(
+                "DELETE FROM peers"
+            )
+
+    @staticmethod
+    def _get_input_peer(peer_id: int, access_hash: int, peer_type: str):
+        if peer_type in ["user", "bot"]:
+            return types.InputPeerUser(
+                user_id=peer_id,
+                access_hash=access_hash
+            )
+
+        if peer_type == "group":
+            return types.InputPeerChat(
+                chat_id=-peer_id
+            )
+
+        if peer_type in ["channel", "supergroup"]:
+            return types.InputPeerChannel(
+                channel_id=int(str(peer_id)[4:]),
+                access_hash=access_hash
+            )
+
+        raise ValueError("Invalid peer type")
+
+    def get_peer_by_id(self, peer_id: int):
+        r = self.conn.execute(
+            "SELECT id, access_hash, type FROM peers WHERE id = ?",
+            (peer_id,)
+        ).fetchone()
+
+        if r is None:
+            raise KeyError("ID not found")
+
+        return self._get_input_peer(*r)
+
+    def get_peer_by_username(self, username: str):
+        r = self.conn.execute(
+            "SELECT id, access_hash, type, last_update_on FROM peers WHERE username = ?",
+            (username,)
+        ).fetchone()
+
+        if r is None:
+            raise KeyError("Username not found")
+
+        if abs(time.time() - r[3]) > self.USERNAME_TTL:
+            raise KeyError("Username expired")
+
+        return self._get_input_peer(*r[:3])
+
+    def get_peer_by_phone_number(self, phone_number: str):
+        r = self.conn.execute(
+            "SELECT id, access_hash, type FROM peers WHERE phone_number = ?",
+            (phone_number,)
+        ).fetchone()
+
+        if r is None:
+            raise KeyError("Phone number not found")
+
+        return self._get_input_peer(*r)
+
+    @property
+    def peers_count(self):
+        return self.conn.execute(
+            "SELECT COUNT(*) FROM peers"
+        ).fetchone()[0]
+
+    def _get(self):
+        attr = inspect.stack()[1].function
+
+        return self.conn.execute(
+            "SELECT {} FROM sessions".format(attr)
+        ).fetchone()[0]
+
+    def _set(self, value):
+        attr = inspect.stack()[1].function
+
+        with self.lock, self.conn:
+            self.conn.execute(
+                "UPDATE sessions SET {} = ?".format(attr),
+                (value,)
+            )
+
+    @property
+    def dc_id(self):
+        return self._get()
+
+    @dc_id.setter
+    def dc_id(self, value):
+        self._set(value)
+
+    @property
+    def test_mode(self):
+        return self._get()
+
+    @test_mode.setter
+    def test_mode(self, value):
+        self._set(value)
+
+    @property
+    def auth_key(self):
+        return self._get()
+
+    @auth_key.setter
+    def auth_key(self, value):
+        self._set(value)
+
+    @property
+    def date(self):
+        return self._get()
+
+    @date.setter
+    def date(self, value):
+        self._set(value)
+
+    @property
+    def user_id(self):
+        return self._get()
+
+    @user_id.setter
+    def user_id(self, value):
+        self._set(value)
+
+    @property
+    def is_bot(self):
+        return self._get()
+
+    @is_bot.setter
+    def is_bot(self, value):
+        self._set(value)
diff --git a/pyrogram/client/storage/schema.sql b/pyrogram/client/storage/schema.sql
new file mode 100644
index 00000000..1f5af6d2
--- /dev/null
+++ b/pyrogram/client/storage/schema.sql
@@ -0,0 +1,34 @@
+CREATE TABLE sessions (
+    dc_id     INTEGER PRIMARY KEY,
+    test_mode INTEGER,
+    auth_key  BLOB,
+    date      INTEGER NOT NULL,
+    user_id   INTEGER,
+    is_bot    INTEGER
+);
+
+CREATE TABLE peers (
+    id             INTEGER PRIMARY KEY,
+    access_hash    INTEGER,
+    type           INTEGER NOT NULL,
+    username       TEXT,
+    phone_number   TEXT,
+    last_update_on INTEGER NOT NULL DEFAULT (CAST(STRFTIME('%s', 'now') AS INTEGER))
+);
+
+CREATE TABLE version (
+    number INTEGER PRIMARY KEY
+);
+
+CREATE INDEX idx_peers_id ON peers (id);
+CREATE INDEX idx_peers_username ON peers (username);
+CREATE INDEX idx_peers_phone_number ON peers (phone_number);
+
+CREATE TRIGGER trg_peers_last_update_on
+    AFTER UPDATE
+    ON peers
+    BEGIN
+        UPDATE peers
+        SET last_update_on = CAST(STRFTIME('%s', 'now') AS INTEGER)
+        WHERE id = NEW.id;
+    END;
\ No newline at end of file