diff --git a/tdrive/backend/node/src/services/documents/entities/drive-file.ts b/tdrive/backend/node/src/services/documents/entities/drive-file.ts
index f5bfe9d6..e4e029a5 100644
--- a/tdrive/backend/node/src/services/documents/entities/drive-file.ts
+++ b/tdrive/backend/node/src/services/documents/entities/drive-file.ts
@@ -135,6 +135,14 @@ const OnlyOfficeSafeDocKeyBase64 = {
   },
 };
 
+function checkFieldValue(field: string, value: string) {
+  if (!/^[0-9a-zA-Z_-]+$/m.test(value))
+    throw new Error(
+      `Invalid ${field} value (${JSON.stringify(
+        value,
+      )}). Must be short and only alpha numeric or '_' and '-'`,
+    );
+}
 /** Reference implementation for generating then parsing the {@link DriveFile.editing_session_key} field */
 export const EditingSessionKeyFormat = {
   // OnlyOffice key limits: 128 chars, [0-9a-zA-Z.=_-]
@@ -145,13 +153,15 @@ export const EditingSessionKeyFormat = {
   // common denominator to all plugin/interop systems. Plugins that
   // require something even stricter have the option of maintaining
   // a look up table to an acceptable value.
-  generate(applicationId: string, companyId: string, userId: string, overrideTimeStamp?: Date) {
-    if (!/^[0-9a-zA-Z_-]+$/m.test(applicationId))
-      throw new Error(
-        `Invalid applicationId string (${JSON.stringify(
-          applicationId,
-        )}). Must be short and only alpha numeric`,
-      );
+  generate(
+    applicationId: string,
+    instanceId: string,
+    companyId: string,
+    userId: string,
+    overrideTimeStamp?: Date,
+  ) {
+    checkFieldValue("applicationId", applicationId);
+    checkFieldValue("instanceId", instanceId);
     const isoUTCDateNoSpecialCharsNoMS = (overrideTimeStamp ?? new Date())
       .toISOString()
       .replace(/\..+$/, "")
@@ -162,7 +172,7 @@ export const EditingSessionKeyFormat = {
     const idsString = OnlyOfficeSafeDocKeyBase64.fromBuffer(
       Buffer.concat([companyIdBuffer, userIdBuffer, entropyBuffer]),
     );
-    const newKey = [isoUTCDateNoSpecialCharsNoMS, applicationId, idsString].join("=");
+    const newKey = [isoUTCDateNoSpecialCharsNoMS, applicationId, instanceId, idsString].join("=");
     if (newKey.length > 128 || !/^[0-9a-zA-Z=_-]+$/m.test(newKey))
       throw new Error(
         `Invalid generated editingSessionKey (${JSON.stringify(
@@ -174,14 +184,14 @@ export const EditingSessionKeyFormat = {
 
   parse(editingSessionKey: string) {
     const parts = editingSessionKey.split("=");
-    const expectedParts = 3;
+    const expectedParts = 4;
     if (parts.length !== expectedParts)
       throw new Error(
         `Invalid editingSessionKey (${JSON.stringify(
           editingSessionKey,
         )}). Expected ${expectedParts} parts`,
       );
-    const [timestampStr, appId, idsOOBase64String] = parts;
+    const [timestampStr, applicationId, instanceId, idsOOBase64String] = parts;
     const timestampMatch = timestampStr.match(
       /^(?<year>\d{4})(?<month>\d\d)(?<day>\d\d)(?<hour>\d\d)(?<minute>\d\d)(?<second>\d\d)$/,
     );
@@ -199,7 +209,8 @@ export const EditingSessionKeyFormat = {
       timestamp: new Date(
         Date.parse(`${[year, month, day].join("-")}T${[hour, minute, second].join(":")}Z`),
       ),
-      applicationId: appId,
+      applicationId,
+      instanceId,
       companyId,
       userId,
     };
diff --git a/tdrive/backend/node/src/services/documents/services/index.ts b/tdrive/backend/node/src/services/documents/services/index.ts
index dabc3778..61e720d8 100644
--- a/tdrive/backend/node/src/services/documents/services/index.ts
+++ b/tdrive/backend/node/src/services/documents/services/index.ts
@@ -967,6 +967,7 @@ export class DocumentsService {
   beginEditing = async (
     id: string,
     editorApplicationId: string,
+    appInstanceId: string,
     context: DriveExecutionContext,
   ) => {
     if (!context) {
@@ -978,6 +979,7 @@ export class DocumentsService {
     try {
       newKey = EditingSessionKeyFormat.generate(
         editorApplicationId,
+        appInstanceId,
         context.company.id,
         context.user.id,
       );
diff --git a/tdrive/backend/node/src/services/documents/web/controllers/documents.ts b/tdrive/backend/node/src/services/documents/web/controllers/documents.ts
index 0084350e..e794117c 100644
--- a/tdrive/backend/node/src/services/documents/web/controllers/documents.ts
+++ b/tdrive/backend/node/src/services/documents/web/controllers/documents.ts
@@ -351,7 +351,7 @@ export class DocumentsController {
     request: FastifyRequest<{
       Params: ItemRequestParams;
       //TODO application id should be received from the token that we have during the login
-      Body: { editorApplicationId: string };
+      Body: { editorApplicationId: string; instanceId: string };
     }>,
   ) => {
     try {
@@ -366,6 +366,7 @@ export class DocumentsController {
       return await globalResolver.services.documents.documents.beginEditing(
         id,
         request.body.editorApplicationId,
+        request.body.instanceId || "",
         context,
       );
     } catch (error) {
diff --git a/tdrive/backend/node/test/unit/core/services/documents/drive-file-editing-sessions-key.test.ts b/tdrive/backend/node/test/unit/core/services/documents/drive-file-editing-sessions-key.test.ts
index 89498de0..c5e10cac 100644
--- a/tdrive/backend/node/test/unit/core/services/documents/drive-file-editing-sessions-key.test.ts
+++ b/tdrive/backend/node/test/unit/core/services/documents/drive-file-editing-sessions-key.test.ts
@@ -7,6 +7,7 @@ describe('DriveFile EditingSessionKeyFormat', () => {
   const mockAppId = 'tdrive_random_application_id';
   const mockCompanyId = randomUUID();
   const mockUserId = randomUUID();
+  const mockInstanceId = "super-instance-id";
   const mockTimestamp = new Date();
   const mockTimestampWith0MS = mockTimestamp.getTime() - (mockTimestamp.getTime() % 1000);
 
@@ -23,31 +24,32 @@ describe('DriveFile EditingSessionKeyFormat', () => {
   test('generates a valid value that can be parsed', async () => {
     checkIsUUID(mockUserId);
     checkIsUUID(mockCompanyId);
-    const key = EditingSessionKeyFormat.generate(mockAppId, mockCompanyId, mockUserId, mockTimestamp);
+    const key = EditingSessionKeyFormat.generate(mockAppId, mockInstanceId, mockCompanyId, mockUserId, mockTimestamp);
     checkKeyIsOOCompatible(key);
     const parsed = EditingSessionKeyFormat.parse(key);
     expect(parsed.applicationId).toBe(mockAppId);
+    expect(parsed.instanceId).toBe(mockInstanceId);
     expect(parsed.userId).toBe(mockUserId);
     expect(parsed.companyId).toBe(mockCompanyId);
     expect(parsed.timestamp.getTime()).toBe(mockTimestampWith0MS);
   });
 
   test('generates unique values', async () => {
-    const key = EditingSessionKeyFormat.generate(mockAppId, mockCompanyId, mockUserId, mockTimestamp);
-    const key2 = EditingSessionKeyFormat.generate(mockAppId, mockCompanyId, mockUserId, mockTimestamp);
+    const key = EditingSessionKeyFormat.generate(mockAppId, mockInstanceId, mockCompanyId, mockUserId, mockTimestamp);
+    const key2 = EditingSessionKeyFormat.generate(mockAppId, mockInstanceId, mockCompanyId, mockUserId, mockTimestamp);
     expect(key).not.toBe(key2);
   });
 
   test('checks the appId', async () => {
     expect(() => {
-      EditingSessionKeyFormat.generate('invalid app id !', mockCompanyId, mockUserId);
-    }).toThrow('Invalid applicationId string');
+      EditingSessionKeyFormat.generate('invalid app id !', mockInstanceId, mockCompanyId, mockUserId);
+    }).toThrow('Invalid applicationId value');
   });
 
   test('checks final length', async () => {
     expect(() => {
       const tooLongAppID = new Array(100).join('x');
-      EditingSessionKeyFormat.generate(tooLongAppID, mockCompanyId, mockUserId);
+      EditingSessionKeyFormat.generate(tooLongAppID, mockInstanceId, mockCompanyId, mockUserId);
     }).toThrow('Must be <128 chars,');
   });
 });
\ No newline at end of file