diff --git a/packages/k6-tests/src/clients/cool/client.ts b/packages/k6-tests/src/clients/cool/client.ts
new file mode 100644
index 0000000..548c9af
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/client.ts
@@ -0,0 +1,88 @@
+import { sleep } from 'k6'
+import { ErrorEvent } from 'k6/experimental/websockets'
+
+import { FileInfo, UserAuth } from './info'
+import { EngineType, MessageType, Session, SocketType } from './io'
+import { docsWorker } from './worker'
+
+export class Client {
+  // @ts-ignore
+  private session: Session
+
+  private token: string
+
+  private documentId: string
+
+  private userAuth: UserAuth
+
+  private fileInfo: FileInfo
+
+  private wopiSrc: string
+
+  constructor(p: { url: string, access_token: string, documentId: string, userAuth: UserAuth, fileInfo: FileInfo }) {
+
+    // eslint-disable-next-line @typescript-eslint/naming-convention
+    const { access_token, access_token_ttl } = p
+
+    const appUrl = new URL(p.url)
+    const wopiSrc = app_url.searchParams.get('WOPISrc')
+
+    const wopiUrl = new URL(wopiSrc)
+    wopiUrl.searchParams.set('access_token', access_token)
+    wopiUrl.searchParams.set('access_token_ttl', access_token_ttl)
+
+    const wssUrl = new URL(`wss://${appUrl.hostname}:${app_url.port}/cool/${encodeURIComponent(wopiUrl)}/ws`)
+    wssUrl.searchParams.set('WOPISrc', wopiSrc)
+    wssUrl.searchParams.set('compat', '/ws')
+
+    this.token = p.token
+    this.documentId = p.documentId
+    this.userAuth = p.userAuth
+    this.fileInfo = p.fileInfo
+    this.wopiSrc = wopiSrc
+    this.session = new Session({ url: wss_url })
+  }
+
+  onError(h: (event?: ErrorEvent) => void) {
+    this.session.onError(h)
+  }
+
+  async establishSession(): Promise<void> {
+    await docsWorker({ session: this.session })
+    await this.session.waitFor({ engineType: EngineType.enum.open })
+    await this.session.publish({ data: `load url=${this.wopiSrc} accessibilityState=false` +
+                                 ' deviceFormFactor=desktop darkTheme=false timezone=America/Montreal' })
+    await this.session.waitFor({ engineType: EngineType.enum.message, socketType: SocketType.enum.connect })
+  }
+
+  async makeChanges(p: { changes: Array<string> }) {
+    await this.session.publish({ data: isSaveLockMessage() })
+    const { messageData: { saveLock: isLocked } } = await this.session.waitFor({
+      engineType: EngineType.enum.message,
+      socketType: SocketType.enum.event,
+      messageType: MessageType.enum.saveLock
+    })
+
+    if (isLocked) {
+      sleep(0.5)
+      await this.makeChanges(p)
+      return
+    }
+
+    p.changes.forEach(async (change) => {
+      await this.session.publish({ data: change })
+    })
+
+    await this.session.publish({ data: 'save dontTerminateEdit=0 dontSaveIfUnmodified=0' })
+
+    await this.session.waitFor({
+      engineType: EngineType.enum.message,
+      socketType: SocketType.enum.event,
+      messageType: MessageType.enum.unSaveLock
+    })
+  }
+
+  disconnect() {
+    this.session.disconnect()
+  }
+}
diff --git a/packages/k6-tests/src/clients/cool/index.ts b/packages/k6-tests/src/clients/cool/index.ts
new file mode 100644
index 0000000..e1868d9
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/index.ts
@@ -0,0 +1,2 @@
+export { Client } from './client'
+export { obtainDocumentInformation } from './info'
diff --git a/packages/k6-tests/src/clients/cool/info.ts b/packages/k6-tests/src/clients/cool/info.ts
new file mode 100644
index 0000000..b4ce123
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/info.ts
@@ -0,0 +1,67 @@
+import { Client } from '@ownclouders/k6-tdk/lib/client'
+import { objectToQueryString } from '@ownclouders/k6-tdk/lib/utils'
+import { z } from 'zod'
+
+const UserAuth = z.object({
+  wopiSrc: z.string(),
+  access_token: z.string(),
+  access_token_ttl: z.number(),
+  userSessionId: z.string(),
+  mode: z.string()
+})
+// eslint-disable-next-line @typescript-eslint/no-redeclare
+export type UserAuth = z.infer<typeof UserAuth>
+
+const FileInfo = z.object({
+  BaseFileName: z.string(),
+  BreadcrumbDocName: z.string(),
+  HostEditUrl: z.string(),
+  HostViewUrl: z.string(),
+  BreadcrumbFolderUrl: z.string(),
+  IsAnonymousUser: z.boolean(),
+  UserFriendlyName: z.string(),
+  BreadcrumbFolderName: z.string(),
+  DownloadUrl: z.string(),
+  FileUrl: z.string(),
+  BreadcrumbBrandName: z.string(),
+  BreadcrumbBrandUrl: z.string(),
+  OwnerId: z.string(),
+  UserId: z.string(),
+  Size: z.number(),
+  Version: z.string(),
+  SupportsExtendedLockLength: z.boolean(),
+  SupportsGetLock: z.boolean(),
+  SupportsUpdate: z.boolean(),
+  UserCanWrite: z.boolean(),
+  SupportsLocks: z.boolean(),
+  SupportsDeleteFile: z.boolean(),
+  UserCanNotWriteRelative: z.boolean(),
+  SupportsRename: z.boolean(),
+  UserCanRename: z.boolean(),
+  SupportsContainers: z.boolean(),
+  SupportsUserInfo: z.boolean()
+})
+// eslint-disable-next-line @typescript-eslint/no-redeclare
+export type FileInfo = z.infer<typeof FileInfo>
+
+export const obtainDocumentInformation = async (p: {
+  client: Client,
+  resourceId: string,
+  appName: string
+}) => {
+  const openRequestParams = { file_id: p.resourceId, lang: 'de', app_name: p.appName }
+  const appOpenResponse = p.client.httpClient<'text'>(
+    'POST',
+    `/app/open?${objectToQueryString(openRequestParams)}`,
+    JSON.stringify(openRequestParams)
+  )
+
+  // eslint-disable-next-line @typescript-eslint/naming-convention
+  const { app_url, form_parameters: { access_token, access_token_ttl } } = JSON.parse(appOpenResponse.body)
+
+  return {
+    app_url,
+    access_token,
+    access_token_ttl
+  }
+}
diff --git a/packages/k6-tests/src/clients/cool/io/index.ts b/packages/k6-tests/src/clients/cool/io/index.ts
new file mode 100644
index 0000000..5e7ba7d
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/io/index.ts
@@ -0,0 +1,2 @@
+export { EngineType, MessageType, SocketType } from '../../onlyoffice/io/io'
+export { Session } from '../../onlyoffice/io/session'
diff --git a/packages/k6-tests/src/clients/cool/utils.ts b/packages/k6-tests/src/clients/cool/utils.ts
new file mode 100644
index 0000000..57d1d4e
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/utils.ts
@@ -0,0 +1,9 @@
+import { EngineType, SocketType } from './io'
+
+export const encodeData = (p: { engineType: EngineType, socketType?: SocketType, data?: unknown }) => {
+  return [p.engineType, p.socketType, JSON.stringify(p.data)]
+    .filter((v) => {
+      return v !== undefined
+    })
+    .join('')
+}
diff --git a/packages/k6-tests/src/clients/cool/worker.ts b/packages/k6-tests/src/clients/cool/worker.ts
new file mode 100644
index 0000000..568895a
--- /dev/null
+++ b/packages/k6-tests/src/clients/cool/worker.ts
@@ -0,0 +1,22 @@
+import { EngineType, MessageType, Session, SocketType } from './io'
+
+export const docsWorker = async (p: { session: Session }): Promise<void> => {
+
+  p.session.subscribe({
+    engineType: EngineType.enum.message,
+    socketType: SocketType.enum.event,
+    messageType: MessageType.enum.error,
+    fn: async ({ messageData }) => {
+      console.error(messageData)
+    }
+  })
+
+  p.session.subscribe({
+    engineType: EngineType.enum.message,
+    socketType: SocketType.enum.event,
+    messageType: MessageType.enum.drop,
+    fn: async ({ messageData }) => {
+      console.error(messageData)
+    }
+  })
+}
diff --git a/packages/k6-tests/src/values/env.ts b/packages/k6-tests/src/values/env.ts
index aca8cd8..542fddc 100644
--- a/packages/k6-tests/src/values/env.ts
+++ b/packages/k6-tests/src/values/env.ts
@@ -153,6 +153,14 @@ export const envValues = () => {
       get app_name() {
         return ENV('ONLY_OFFICE_APP_NAME', 'OnlyOffice')
       }
+    },
+    cool: {
+      get wss_url() {
+        return ENV('COOL_WSS_URL', 'wss://localhost:9980/')
+      },
+      get app_name() {
+        return ENV('COOL_APP_NAME', 'Collabora')
+      }
     }
   }
 
diff --git a/packages/k6-tests/tests/koko/cool/010-open-change-save/baseline.k6.ts b/packages/k6-tests/tests/koko/cool/010-open-change-save/baseline.k6.ts
new file mode 100644
index 0000000..ce0f26c
--- /dev/null
+++ b/packages/k6-tests/tests/koko/cool/010-open-change-save/baseline.k6.ts
@@ -0,0 +1,14 @@
+import { Options } from 'k6/options'
+
+import { open_change_save_010, open_change_save_010_setup, open_change_save_010_teardown, options as inherited_options } from './simple.k6'
+
+export const options: Options = {
+  ...inherited_options,
+  iterations: 10,
+  duration: '7d',
+  teardownTimeout: '1h'
+}
+
+export const setup = open_change_save_010_setup
+export default open_change_save_010
+export const teardown = open_change_save_010_teardown
diff --git a/packages/k6-tests/tests/koko/cool/010-open-change-save/ramping.k6.ts b/packages/k6-tests/tests/koko/cool/010-open-change-save/ramping.k6.ts
new file mode 100644
index 0000000..ee0641b
--- /dev/null
+++ b/packages/k6-tests/tests/koko/cool/010-open-change-save/ramping.k6.ts
@@ -0,0 +1,22 @@
+import { Options } from 'k6/options'
+import { omit } from 'lodash'
+
+import { options as inherited_options } from './baseline.k6'
+
+export { open_change_save_010, open_change_save_010_setup as setup, open_change_save_010_teardown as teardown } from './simple.k6'
+
+export const options: Options = {
+  ...omit(inherited_options, 'iterations', 'duration'),
+  scenarios: {
+    open_change_save_010: {
+      executor: 'ramping-vus',
+      startVUs: 0,
+      exec: 'open_change_save_010',
+      stages: [
+        { target: 10, duration: '20s' },
+        { target: 10, duration: '30s' },
+        { target: 0, duration: '10s' }
+      ]
+    }
+  }
+}
diff --git a/packages/k6-tests/tests/koko/cool/010-open-change-save/simple.k6.ts b/packages/k6-tests/tests/koko/cool/010-open-change-save/simple.k6.ts
new file mode 100644
index 0000000..081a225
--- /dev/null
+++ b/packages/k6-tests/tests/koko/cool/010-open-change-save/simple.k6.ts
@@ -0,0 +1,133 @@
+import { ENV, queryXml, store } from '@ownclouders/k6-tdk/lib/utils'
+import { sleep } from 'k6'
+import exec from 'k6/execution'
+import { Counter } from 'k6/metrics'
+import { Options } from 'k6/options'
+
+import { Client, obtainDocumentInformation } from '@/clients/cool'
+import { userPool } from '@/pools'
+import { clientFor } from '@/shortcuts'
+import { getTestRoot } from '@/test'
+import { getPoolItem } from '@/utils'
+import { envValues } from '@/values'
+
+export interface Environment {
+  testRoot: string;
+}
+
+// eslint-disable-next-line no-restricted-globals
+const docX = open('../data/sample.docx', 'b')
+
+export const options: Options = {
+  vus: 1,
+  iterations: 1,
+  insecureSkipTLSVerify: true
+}
+
+const settings = {
+  ...envValues(),
+  get docx() {
+    return ENV('DOCX', [settings.seed.resource.root, 'sample.docx'].join('/'))
+  }
+}
+
+const coolClientErrors = new Counter('cool_client_errors')
+
+export const open_change_save_010_setup = async (): Promise<Environment> => {
+  const adminClient = clientFor({ userLogin: settings.admin.login, userPassword: settings.admin.password })
+  const rootInfo = await getTestRoot({
+    client: adminClient,
+    userLogin: settings.admin.login,
+    platform: settings.platform.type,
+    resourceName: settings.seed.container.name,
+    resourceType: settings.seed.container.type,
+    isOwner: false
+  })
+
+  const testRoot = [rootInfo.root, rootInfo.path].join('/')
+
+  adminClient.resource.uploadResource({
+    root: testRoot,
+    resourcePath: settings.docx,
+    resourceBytes: docX
+  })
+
+  return {
+    testRoot
+  }
+}
+
+export const open_change_save_010 = async ({ testRoot }: Environment): Promise<void> => {
+  const user = getPoolItem({ pool: userPool, n: exec.vu.idInTest })
+  const userStore = store(user.userLogin)
+  const documentInformation = await userStore.setOrGet('root', async () => {
+    const ocisClient = clientFor(user)
+
+    const getResourcePropertiesResponse = await ocisClient.resource.getResourceProperties({
+      root: testRoot,
+      resourcePath: settings.docx
+    })
+    sleep(settings.sleep.after_request)
+
+    const [resourceId] = queryXml("$..['oc:fileid']", getResourcePropertiesResponse.body)
+    return obtainDocumentInformation({ client: ocisClient, appName: settings.cool.app_name, resourceId })
+  })
+
+  const { app_url } = documentInformation
+
+  const coolClient = new Client({
+    ...documentInformation,
+    url: app_url
+  })
+
+  coolClient.onError((err) => {
+    console.error(err?.error)
+    coolClientErrors.add(1, { errorType: err?.error || 'unknown' })
+  })
+
+  await coolClient.establishSession()
+  sleep(settings.sleep.after_request)
+
+  // todo: move into pool
+  const changes = [
+    'textinput id=0 text=H',
+    'textinput id=0 text=e',
+    'textinput id=0 text=l',
+    'textinput id=0 text=l',
+    'textinput id=0 text=o',
+    'key type=input char=32 key=0',
+    'textinput id=0 text=w',
+    'textinput id=0 text=o',
+    'textinput id=0 text=r',
+    'textinput id=0 text=l',
+    'textinput id=0 text=d',
+    'key type=input char=33 key=0'
+  ]
+
+  await coolClient.makeChanges({ changes })
+  sleep(settings.sleep.after_request)
+
+  coolClient.disconnect()
+  sleep(settings.sleep.after_iteration)
+}
+
+export const open_change_save_010_teardown = ({ testRoot }: Environment): void => {
+  const adminClient = clientFor({ userLogin: settings.admin.login, userPassword: settings.admin.password })
+
+  const waitForUnlock = () => {
+    const { body } = adminClient.resource.getResourceProperties({ root: testRoot, resourcePath: settings.docx })
+
+    if(queryXml("$..['d:activelock']", body).length !== 0){
+      sleep(1)
+      waitForUnlock()
+    }
+  }
+
+  waitForUnlock()
+
+  adminClient.resource.deleteResource({ root: testRoot, resourcePath: settings.docx })
+}
+
+export const setup = open_change_save_010_setup
+export default open_change_save_010
+export const teardown = open_change_save_010_teardown