diff --git a/README.rst b/README.rst
index a2a893a5..6f7477ca 100644
--- a/README.rst
+++ b/README.rst
@@ -36,6 +36,7 @@ List of currently supported connections:
 * Clickhouse
 * Postgres
 * Oracle
+* MSSQL
 * HDFS
 * S3
 
diff --git a/docs/changelog/next_release/125.feature.rst b/docs/changelog/next_release/125.feature.rst
new file mode 100644
index 00000000..0aed705b
--- /dev/null
+++ b/docs/changelog/next_release/125.feature.rst
@@ -0,0 +1 @@
+Add MSSQL API schema
\ No newline at end of file
diff --git a/syncmaster/backend/api/v1/connections.py b/syncmaster/backend/api/v1/connections.py
index 47296f4d..678656a1 100644
--- a/syncmaster/backend/api/v1/connections.py
+++ b/syncmaster/backend/api/v1/connections.py
@@ -21,6 +21,7 @@
     CLICKHOUSE_TYPE,
     HDFS_TYPE,
     HIVE_TYPE,
+    MSSQL_TYPE,
     ORACLE_TYPE,
     POSTGRES_TYPE,
     S3_TYPE,
@@ -38,7 +39,7 @@
 
 router = APIRouter(tags=["Connections"], responses=get_error_responses())
 
-CONNECTION_TYPES = ORACLE_TYPE, POSTGRES_TYPE, CLICKHOUSE_TYPE, HIVE_TYPE, S3_TYPE, HDFS_TYPE
+CONNECTION_TYPES = ORACLE_TYPE, POSTGRES_TYPE, CLICKHOUSE_TYPE, HIVE_TYPE, MSSQL_TYPE, S3_TYPE, HDFS_TYPE
 
 
 @router.get("/connections")
diff --git a/syncmaster/schemas/v1/connection_types.py b/syncmaster/schemas/v1/connection_types.py
index f21774d9..924493a3 100644
--- a/syncmaster/schemas/v1/connection_types.py
+++ b/syncmaster/schemas/v1/connection_types.py
@@ -7,6 +7,7 @@
 ORACLE_TYPE = Literal["oracle"]
 POSTGRES_TYPE = Literal["postgres"]
 CLICKHOUSE_TYPE = Literal["clickhouse"]
+MSSQL_TYPE = Literal["mssql"]
 S3_TYPE = Literal["s3"]
 HDFS_TYPE = Literal["hdfs"]
 
@@ -16,5 +17,6 @@ class ConnectionType(str, Enum):
     HIVE = "hive"
     ORACLE = "oracle"
     CLICKHOUSE = "clickhouse"
+    MSSQL = "mssql"
     S3 = "s3"
     HDFS = "hdfs"
diff --git a/syncmaster/schemas/v1/connections/connection.py b/syncmaster/schemas/v1/connections/connection.py
index b9b86aaa..ff597940 100644
--- a/syncmaster/schemas/v1/connections/connection.py
+++ b/syncmaster/schemas/v1/connections/connection.py
@@ -27,6 +27,14 @@
     UpdateHiveAuthSchema,
     UpdateHiveConnectionSchema,
 )
+from syncmaster.schemas.v1.connections.mssql import (
+    CreateMSSQLAuthSchema,
+    CreateMSSQLConnectionSchema,
+    ReadMSSQLAuthSchema,
+    ReadMSSQLConnectionSchema,
+    UpdateMSSQLAuthSchema,
+    UpdateMSSQLConnectionSchema,
+)
 from syncmaster.schemas.v1.connections.oracle import (
     CreateOracleAuthSchema,
     CreateOracleConnectionSchema,
@@ -60,6 +68,7 @@
     | ReadOracleConnectionSchema
     | ReadPostgresConnectionSchema
     | ReadClickhouseConnectionSchema
+    | ReadMSSQLConnectionSchema
     | S3ReadConnectionSchema
 )
 CreateConnectionDataSchema = (
@@ -67,6 +76,7 @@
     | CreateOracleConnectionSchema
     | CreatePostgresConnectionSchema
     | CreateClickhouseConnectionSchema
+    | CreateMSSQLConnectionSchema
     | HDFSCreateConnectionSchema
     | S3CreateConnectionSchema
 )
@@ -77,12 +87,14 @@
     | UpdateOracleConnectionSchema
     | UpdatePostgresConnectionSchema
     | UpdateClickhouseConnectionSchema
+    | UpdateMSSQLConnectionSchema
 )
 ReadConnectionAuthDataSchema = (
     ReadHiveAuthSchema
     | ReadOracleAuthSchema
     | ReadPostgresAuthSchema
     | ReadClickhouseAuthSchema
+    | ReadMSSQLAuthSchema
     | S3ReadAuthSchema
     | HDFSReadAuthSchema
 )
@@ -91,6 +103,7 @@
     | CreateOracleAuthSchema
     | CreatePostgresAuthSchema
     | CreateClickhouseAuthSchema
+    | CreateMSSQLAuthSchema
     | S3CreateAuthSchema
     | HDFSCreateAuthSchema
 )
@@ -99,6 +112,7 @@
     | UpdateOracleAuthSchema
     | UpdatePostgresAuthSchema
     | UpdateClickhouseAuthSchema
+    | UpdateMSSQLAuthSchema
     | S3UpdateAuthSchema
     | HDFSUpdateAuthSchema
 )
diff --git a/syncmaster/schemas/v1/connections/mssql.py b/syncmaster/schemas/v1/connections/mssql.py
new file mode 100644
index 00000000..b560bd00
--- /dev/null
+++ b/syncmaster/schemas/v1/connections/mssql.py
@@ -0,0 +1,47 @@
+# SPDX-FileCopyrightText: 2023-2024 MTS PJSC
+# SPDX-License-Identifier: Apache-2.0
+from pydantic import BaseModel, Field, SecretStr
+
+from syncmaster.schemas.v1.connection_types import MSSQL_TYPE
+
+
+class MSSQLBaseSchema(BaseModel):
+    type: MSSQL_TYPE
+
+    class Config:
+        from_attributes = True
+
+
+class ReadMSSQLConnectionSchema(MSSQLBaseSchema):
+    host: str
+    port: int
+    database: str
+    additional_params: dict = Field(default_factory=dict)
+
+
+class ReadMSSQLAuthSchema(MSSQLBaseSchema):
+    user: str
+
+
+class UpdateMSSQLConnectionSchema(MSSQLBaseSchema):
+    host: str | None = None
+    port: int | None = None
+    database: str | None = None
+    additional_params: dict | None = Field(default_factory=dict)
+
+
+class UpdateMSSQLAuthSchema(MSSQLBaseSchema):
+    user: str | None = None  # noqa: F722
+    password: SecretStr | None = None
+
+
+class CreateMSSQLConnectionSchema(MSSQLBaseSchema):
+    host: str
+    port: int
+    database: str
+    additional_params: dict = Field(default_factory=dict)
+
+
+class CreateMSSQLAuthSchema(MSSQLBaseSchema):
+    user: str
+    password: SecretStr
diff --git a/syncmaster/schemas/v1/transfers/__init__.py b/syncmaster/schemas/v1/transfers/__init__.py
index d6c7d662..b998e3dd 100644
--- a/syncmaster/schemas/v1/transfers/__init__.py
+++ b/syncmaster/schemas/v1/transfers/__init__.py
@@ -9,6 +9,7 @@
 from syncmaster.schemas.v1.transfers.db import (
     ClickhouseReadTransferSourceAndTarget,
     HiveReadTransferSourceAndTarget,
+    MSSQLReadTransferSourceAndTarget,
     OracleReadTransferSourceAndTarget,
     PostgresReadTransferSourceAndTarget,
 )
@@ -33,6 +34,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3ReadTransferSource
 )
 
@@ -42,6 +44,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3ReadTransferTarget
 )
 
@@ -51,6 +54,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3CreateTransferSource
 )
 
@@ -60,6 +64,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3CreateTransferTarget
 )
 
@@ -69,6 +74,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3CreateTransferSource
     | None
 )
@@ -79,6 +85,7 @@
     | HiveReadTransferSourceAndTarget
     | OracleReadTransferSourceAndTarget
     | ClickhouseReadTransferSourceAndTarget
+    | MSSQLReadTransferSourceAndTarget
     | S3CreateTransferTarget
     | None
 )
diff --git a/syncmaster/schemas/v1/transfers/db.py b/syncmaster/schemas/v1/transfers/db.py
index 5618cb71..751bf57a 100644
--- a/syncmaster/schemas/v1/transfers/db.py
+++ b/syncmaster/schemas/v1/transfers/db.py
@@ -7,6 +7,7 @@
 from syncmaster.schemas.v1.connection_types import (
     CLICKHOUSE_TYPE,
     HIVE_TYPE,
+    MSSQL_TYPE,
     ORACLE_TYPE,
     POSTGRES_TYPE,
 )
@@ -30,3 +31,7 @@ class PostgresReadTransferSourceAndTarget(ReadDBTransfer):
 
 class ClickhouseReadTransferSourceAndTarget(ReadDBTransfer):
     type: CLICKHOUSE_TYPE
+
+
+class MSSQLReadTransferSourceAndTarget(ReadDBTransfer):
+    type: MSSQL_TYPE
diff --git a/tests/test_unit/test_connections/connection_fixtures/group_connections_fixture.py b/tests/test_unit/test_connections/connection_fixtures/group_connections_fixture.py
index ce188e10..b698ffa1 100644
--- a/tests/test_unit/test_connections/connection_fixtures/group_connections_fixture.py
+++ b/tests/test_unit/test_connections/connection_fixtures/group_connections_fixture.py
@@ -1,3 +1,5 @@
+from collections.abc import AsyncGenerator
+
 import pytest_asyncio
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -7,7 +9,10 @@
 
 
 @pytest_asyncio.fixture
-async def group_connections(group_connection: MockConnection, session: AsyncSession) -> list[MockConnection]:
+async def group_connections(
+    group_connection: MockConnection,
+    session: AsyncSession,
+) -> AsyncGenerator[list[MockConnection], None]:
     connection = group_connection.connection
 
     # start with the connection from group_connection fixture
@@ -17,13 +22,36 @@ async def group_connections(group_connection: MockConnection, session: AsyncSess
     # since group_connection already created a connection, we start from index 1
     for conn_type in connection_types[1:]:
 
-        new_data = {  # TODO: create different dicts
+        new_data = {
             **connection.data,
             "type": conn_type.value,
-            "cluster": "cluster",
-            "bucket": "bucket",
         }
 
+        if conn_type in [ConnectionType.HDFS, ConnectionType.HIVE]:
+            new_data.update(
+                {
+                    "cluster": "cluster",
+                },
+            )
+        elif conn_type == ConnectionType.S3:
+            new_data.update(
+                {
+                    "bucket": "bucket",
+                },
+            )
+        elif conn_type == ConnectionType.POSTGRES:
+            new_data.update(
+                {
+                    "database_name": "database",
+                },
+            )
+        elif conn_type in [ConnectionType.ORACLE, ConnectionType.CLICKHOUSE, ConnectionType.MSSQL]:
+            new_data.update(
+                {
+                    "database": "database",
+                },
+            )
+
         new_connection = Connection(
             group_id=connection.group_id,
             name=f"{connection.name}_{conn_type.value}",
diff --git a/tests/test_unit/test_connections/test_create_connection.py b/tests/test_unit/test_connections/test_create_connection.py
index e4439faf..e0a43ec8 100644
--- a/tests/test_unit/test_connections/test_create_connection.py
+++ b/tests/test_unit/test_connections/test_create_connection.py
@@ -282,7 +282,7 @@ async def test_check_fields_validation_on_create_connection(
                     "context": {
                         "discriminator": "'type'",
                         "tag": "POSTGRESQL",
-                        "expected_tags": "'hive', 'oracle', 'postgres', 'clickhouse', 'hdfs', 's3'",
+                        "expected_tags": "'hive', 'oracle', 'postgres', 'clickhouse', 'mssql', 'hdfs', 's3'",
                     },
                     "input": {
                         "type": "POSTGRESQL",
@@ -292,7 +292,7 @@ async def test_check_fields_validation_on_create_connection(
                         "database_name": "postgres",
                     },
                     "location": ["body", "connection_data"],
-                    "message": "Input tag 'POSTGRESQL' found using 'type' does not match any of the expected tags: 'hive', 'oracle', 'postgres', 'clickhouse', 'hdfs', 's3'",
+                    "message": "Input tag 'POSTGRESQL' found using 'type' does not match any of the expected tags: 'hive', 'oracle', 'postgres', 'clickhouse', 'mssql', 'hdfs', 's3'",
                     "code": "union_tag_invalid",
                 },
             ],
diff --git a/tests/test_unit/test_connections/test_db_connection/test_create_mssql_connection.py b/tests/test_unit/test_connections/test_db_connection/test_create_mssql_connection.py
new file mode 100644
index 00000000..62d4f3e1
--- /dev/null
+++ b/tests/test_unit/test_connections/test_db_connection/test_create_mssql_connection.py
@@ -0,0 +1,80 @@
+import pytest
+from httpx import AsyncClient
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from syncmaster.db.models import AuthData, Connection
+from syncmaster.db.repositories.utils import decrypt_auth_data
+from syncmaster.settings import Settings
+from tests.mocks import MockGroup, UserTestRoles
+
+pytestmark = [pytest.mark.asyncio, pytest.mark.backend, pytest.mark.mssql]
+
+
+async def test_developer_plus_can_create_mssql_connection(
+    client: AsyncClient,
+    group: MockGroup,
+    session: AsyncSession,
+    settings: Settings,
+    role_developer_plus: UserTestRoles,
+):
+    # Arrange
+    user = group.get_member_of_role(role_developer_plus)
+
+    # Act
+    result = await client.post(
+        "v1/connections",
+        headers={"Authorization": f"Bearer {user.token}"},
+        json={
+            "group_id": group.id,
+            "name": "New connection",
+            "description": "",
+            "connection_data": {
+                "type": "mssql",
+                "host": "127.0.0.1",
+                "port": 1433,
+                "database": "database_name",
+            },
+            "auth_data": {
+                "type": "mssql",
+                "user": "user",
+                "password": "secret",
+            },
+        },
+    )
+    connection = (
+        await session.scalars(
+            select(Connection).filter_by(
+                name="New connection",
+            ),
+        )
+    ).first()
+
+    creds = (
+        await session.scalars(
+            select(AuthData).filter_by(
+                connection_id=connection.id,
+            ),
+        )
+    ).one()
+
+    # Assert
+    decrypted = decrypt_auth_data(creds.value, settings=settings)
+    assert result.status_code == 200
+    assert result.json() == {
+        "id": connection.id,
+        "name": connection.name,
+        "description": connection.description,
+        "group_id": connection.group_id,
+        "connection_data": {
+            "type": connection.data["type"],
+            "host": connection.data["host"],
+            "port": connection.data["port"],
+            "database": connection.data["database"],
+            "additional_params": connection.data["additional_params"],
+        },
+        "auth_data": {
+            "type": decrypted["type"],
+            "user": decrypted["user"],
+        },
+    }
diff --git a/tests/test_unit/test_connections/test_db_connection/test_update_mssql_connection.py b/tests/test_unit/test_connections/test_db_connection/test_update_mssql_connection.py
new file mode 100644
index 00000000..f2942ad8
--- /dev/null
+++ b/tests/test_unit/test_connections/test_db_connection/test_update_mssql_connection.py
@@ -0,0 +1,72 @@
+import pytest
+from httpx import AsyncClient
+
+from tests.mocks import MockConnection, UserTestRoles
+
+pytestmark = [pytest.mark.asyncio, pytest.mark.backend, pytest.mark.mssql]
+
+
+@pytest.mark.parametrize(
+    "create_connection_data,create_connection_auth_data",
+    [
+        (
+            {
+                "type": "mssql",
+                "host": "127.0.0.1",
+                "port": 1433,
+                "database": "name",
+            },
+            {
+                "type": "mssql",
+                "user": "user",
+                "password": "secret",
+            },
+        ),
+    ],
+    indirect=True,
+)
+async def test_developer_plus_can_update_mssql_connection(
+    client: AsyncClient,
+    group_connection: MockConnection,
+    role_developer_plus: UserTestRoles,
+):
+    # Arrange
+    user = group_connection.owner_group.get_member_of_role(role_developer_plus)
+    group_connection.connection.group.id
+
+    # Act
+    result = await client.patch(
+        f"v1/connections/{group_connection.id}",
+        headers={"Authorization": f"Bearer {user.token}"},
+        json={
+            "connection_data": {
+                "type": "mssql",
+                "host": "127.0.1.1",
+                "database": "new_name",
+            },
+            "auth_data": {
+                "type": "mssql",
+                "user": "new_user",
+            },
+        },
+    )
+
+    # Assert
+    assert result.status_code == 200
+    assert result.json() == {
+        "id": group_connection.id,
+        "name": group_connection.name,
+        "description": group_connection.description,
+        "group_id": group_connection.group_id,
+        "connection_data": {
+            "type": group_connection.data["type"],
+            "host": "127.0.1.1",
+            "port": group_connection.data["port"],
+            "database": "new_name",
+            "additional_params": {},
+        },
+        "auth_data": {
+            "type": group_connection.credentials.value["type"],
+            "user": "new_user",
+        },
+    }
diff --git a/tests/test_unit/test_connections/test_read_connections.py b/tests/test_unit/test_connections/test_read_connections.py
index 455a223a..3cb6e124 100644
--- a/tests/test_unit/test_connections/test_read_connections.py
+++ b/tests/test_unit/test_connections/test_read_connections.py
@@ -307,10 +307,10 @@ async def test_search_connections_with_nonexistent_query(
 @pytest.mark.parametrize(
     "filter_params, expected_total",
     [
-        ({}, 6),  # No filters applied, expecting all connections
+        ({}, 7),  # No filters applied, expecting all connections
         ({"type": ["oracle"]}, 1),
         ({"type": ["postgres", "hive"]}, 2),
-        ({"type": ["postgres", "hive", "oracle", "clickhouse", "hdfs", "s3"]}, 6),
+        ({"type": ["postgres", "hive", "oracle", "clickhouse", "mssql", "hdfs", "s3"]}, 7),
     ],
     ids=[
         "no_filters",
diff --git a/tests/test_unit/test_transfers/test_create_transfer.py b/tests/test_unit/test_transfers/test_create_transfer.py
index ae393f12..67a3bb5d 100644
--- a/tests/test_unit/test_transfers/test_create_transfer.py
+++ b/tests/test_unit/test_transfers/test_create_transfer.py
@@ -370,12 +370,12 @@ async def test_superuser_can_create_transfer(
                             "location": ["body", "source_params"],
                             "message": (
                                 "Input tag 'new some connection type' found using 'type' "
-                                "does not match any of the expected tags: 'postgres', 'hdfs', 'hive', 'oracle', 'clickhouse', 's3'"
+                                "does not match any of the expected tags: 'postgres', 'hdfs', 'hive', 'oracle', 'clickhouse', 'mssql', 's3'"
                             ),
                             "code": "union_tag_invalid",
                             "context": {
                                 "discriminator": "'type'",
-                                "expected_tags": "'postgres', 'hdfs', 'hive', 'oracle', 'clickhouse', 's3'",
+                                "expected_tags": "'postgres', 'hdfs', 'hive', 'oracle', 'clickhouse', 'mssql', 's3'",
                                 "tag": "new some connection type",
                             },
                             "input": {
diff --git a/tests/test_unit/test_transfers/transfer_fixtures/transfers_fixture.py b/tests/test_unit/test_transfers/transfer_fixtures/transfers_fixture.py
index 17063024..f02d1998 100644
--- a/tests/test_unit/test_transfers/transfer_fixtures/transfers_fixture.py
+++ b/tests/test_unit/test_transfers/transfer_fixtures/transfers_fixture.py
@@ -81,6 +81,7 @@ async def group_transfers(
             ConnectionType.POSTGRES,
             ConnectionType.ORACLE,
             ConnectionType.CLICKHOUSE,
+            ConnectionType.MSSQL,
         ]:
             source_params["table_name"] = "source_table"
             target_params["table_name"] = "target_table"