diff --git a/packages/repl/src/components/settings/AccountsTab.tsx b/packages/repl/src/components/settings/AccountsTab.tsx
index db69fef..d74d4a3 100644
--- a/packages/repl/src/components/settings/AccountsTab.tsx
+++ b/packages/repl/src/components/settings/AccountsTab.tsx
@@ -1,24 +1,26 @@
 import type { DropdownMenuTriggerProps } from '@kobalte/core/dropdown-menu'
 import type { TooltipTriggerProps } from '@kobalte/core/tooltip'
-import type { TelegramAccount } from 'mtcute-repl-worker/client'
+import type { CustomApiFields, TelegramAccount } from 'mtcute-repl-worker/client'
 import type { LoginStep } from './login/Login.tsx'
 import { timers, unknownToError } from '@fuman/utils'
 import {
   LucideBot,
+  LucideChevronDown,
   LucideChevronRight,
   LucideEllipsis,
+  LucideFlaskConical,
   LucideFolderUp,
   LucideLogIn,
-  LucidePlus,
   LucideRefreshCw,
   LucideSearch,
+  LucideServerCog,
   LucideTrash,
   LucideTriangleAlert,
   LucideUser,
   LucideX,
 } from 'lucide-solid'
-import { workerInvoke } from 'mtcute-repl-worker/client'
 
+import { workerInvoke } from 'mtcute-repl-worker/client'
 import { nanoid } from 'nanoid'
 import { createEffect, createMemo, createSignal, For, on, onCleanup, Show } from 'solid-js'
 import { toast } from 'solid-sonner'
@@ -36,11 +38,13 @@ import { useStore } from '../../store/use-store.ts'
 import { AccountAvatar } from '../AccountAvatar.tsx'
 import { ImportDropdown } from './import/ImportDropdown.tsx'
 import { StringSessionDefs } from './import/StringSessionImportDialog.tsx'
+import { CustomApiDialog } from './login/CustomApiDialog.tsx'
 import { LoginForm } from './login/Login.tsx'
 
 function AddAccountDialog(props: {
   show: boolean
   testMode: boolean
+  apiOptions?: CustomApiFields
   onClose: () => void
 }) {
   const [accountId, setAccountId] = createSignal<string | undefined>(undefined)
@@ -81,6 +85,7 @@ function AddAccountDialog(props: {
     await workerInvoke('telegram', 'createClient', {
       accountId: accountId()!,
       testMode: props.testMode,
+      apiOptions: props.apiOptions,
     })
   }))
 
@@ -281,17 +286,71 @@ function AccountRow(props: {
   )
 }
 
+type AddAccountMode = 'test' | 'custom-api' | 'normal'
+function LoginButton(props: {
+  size: 'xs' | 'sm'
+  onAddAccount: (mode: AddAccountMode) => void
+}) {
+  const [showDropdown, setShowDropdown] = createSignal(false)
+
+  return (
+    <div class="flex flex-row items-center">
+      <Button
+        variant="outline"
+        size={props.size}
+        onClick={() => props.onAddAccount('normal')}
+        class="rounded-r-none"
+      >
+        Log in
+      </Button>
+      <DropdownMenu
+        open={showDropdown()}
+        onOpenChange={setShowDropdown}
+      >
+        <DropdownMenuTrigger>
+          <Button
+            variant="outline"
+            size={props.size}
+            class="w-6 rounded-l-none border-l-0"
+          >
+            <LucideChevronDown class="size-3 shrink-0" />
+          </Button>
+        </DropdownMenuTrigger>
+        <DropdownMenuContent>
+          <DropdownMenuItem class="py-1 text-xs" onClick={() => props.onAddAccount('test')}>
+            <LucideFlaskConical class="mr-2 size-3.5 stroke-[1.5px]" />
+            Use test server
+          </DropdownMenuItem>
+          <DropdownMenuItem class="py-1 text-xs" onClick={() => props.onAddAccount('custom-api')}>
+            <LucideServerCog class="mr-2 size-3.5 stroke-[1.5px]" />
+            Use custom API
+          </DropdownMenuItem>
+        </DropdownMenuContent>
+      </DropdownMenu>
+    </div>
+  )
+}
+
 export function AccountsTab() {
   const accounts = useStore($accounts)
   const activeAccountId = useStore($activeAccountId)
   const [showAddAccount, setShowAddAccount] = createSignal(false)
   const [addAccountTestMode, setAddAccountTestMode] = createSignal(false)
+  const [addAccountOptions, setAddAccountOptions] = createSignal<CustomApiFields>()
 
   const [searchQuery, setSearchQuery] = createSignal('')
 
-  function handleAddAccount(e: MouseEvent) {
+  const [showCustomApi, setShowCustomApi] = createSignal(false)
+
+  function handleAddAccount(mode: AddAccountMode) {
+    if (mode === 'custom-api') {
+      setShowCustomApi(true)
+      return
+    }
+
     setShowAddAccount(true)
-    setAddAccountTestMode(e.ctrlKey || e.metaKey)
+    setAddAccountTestMode(mode === 'test')
+    setAddAccountOptions(undefined)
   }
 
   const filteredAccounts = createMemo(() => {
@@ -329,14 +388,7 @@ export function AccountsTab() {
 
             No accounts yet
             <div class="flex flex-row gap-2">
-              <Button
-                variant="outline"
-                size="sm"
-                onClick={handleAddAccount}
-              >
-                <LucidePlus class="mr-2 size-4" />
-                Log in
-              </Button>
+              <LoginButton size="sm" onAddAccount={handleAddAccount} />
               <ImportDropdown size="sm" />
             </div>
           </div>
@@ -363,15 +415,7 @@ export function AccountsTab() {
               </TextFieldFrame>
             </TextFieldRoot>
 
-            <Button
-              variant="outline"
-              size="xs"
-              onClick={handleAddAccount}
-            >
-              <LucidePlus class="mr-2 size-3" />
-              Log in
-            </Button>
-
+            <LoginButton size="xs" onAddAccount={handleAddAccount} />
             <ImportDropdown size="xs" />
           </div>
           <div class="flex max-w-full flex-col gap-1 overflow-hidden">
@@ -391,8 +435,19 @@ export function AccountsTab() {
       <AddAccountDialog
         show={showAddAccount()}
         testMode={addAccountTestMode()}
+        apiOptions={addAccountOptions()}
         onClose={() => setShowAddAccount(false)}
       />
+
+      <CustomApiDialog
+        visible={showCustomApi()}
+        setVisible={setShowCustomApi}
+        onSubmit={(options) => {
+          setShowCustomApi(false)
+          setAddAccountOptions(options)
+          setShowAddAccount(true)
+        }}
+      />
     </>
   )
 }
diff --git a/packages/repl/src/components/settings/login/CustomApiDialog.tsx b/packages/repl/src/components/settings/login/CustomApiDialog.tsx
new file mode 100644
index 0000000..7fa51c1
--- /dev/null
+++ b/packages/repl/src/components/settings/login/CustomApiDialog.tsx
@@ -0,0 +1,176 @@
+import type { CustomApiFields } from 'mtcute-repl-worker/client'
+import type { SetStoreFunction } from 'solid-js/store'
+import { createSignal, Show } from 'solid-js'
+import { createStore, unwrap } from 'solid-js/store'
+import { Button } from '../../../lib/components/ui/button.tsx'
+import { Checkbox, CheckboxControl, CheckboxLabel } from '../../../lib/components/ui/checkbox.tsx'
+import { Dialog, DialogContent, DialogHeader } from '../../../lib/components/ui/dialog.tsx'
+import { TextField, TextFieldFrame, TextFieldLabel, TextFieldRoot } from '../../../lib/components/ui/text-field.tsx'
+
+export function useCustomApiFormState() {
+  // eslint-disable-next-line solid/reactivity
+  return createStore<CustomApiFields>({
+    apiId: '',
+    apiHash: '',
+    deviceModel: '',
+    systemVersion: '',
+    appVersion: '',
+    systemLangCode: '',
+    langPack: '',
+    langCode: '',
+    extraJson: '',
+  })
+}
+
+export function CustomApiForm(props: {
+  class?: string
+  state: CustomApiFields
+  setState: SetStoreFunction<CustomApiFields>
+}) {
+  const [showAdvanced, setShowAdvanced] = createSignal(false)
+
+  return (
+    <div class="flex flex-col gap-2">
+      <TextFieldRoot>
+        <TextFieldLabel>API ID</TextFieldLabel>
+        <TextFieldFrame>
+          <TextField
+            placeholder="2040"
+            value={props.state.apiId}
+            onInput={e => props.setState('apiId', e.currentTarget.value.replace(/\D/g, ''))}
+          />
+        </TextFieldFrame>
+      </TextFieldRoot>
+      <TextFieldRoot>
+        <TextFieldLabel>API Hash</TextFieldLabel>
+        <TextFieldFrame>
+          <TextField
+            placeholder="b18441..."
+            value={props.state.apiHash}
+            onInput={e => props.setState('apiHash', e.currentTarget.value)}
+          />
+        </TextFieldFrame>
+      </TextFieldRoot>
+
+      <Checkbox
+        checked={showAdvanced()}
+        onChange={setShowAdvanced}
+        class="my-2 flex flex-row items-center gap-2 text-sm"
+      >
+        <CheckboxControl />
+        <CheckboxLabel>
+          Show advanced fields
+        </CheckboxLabel>
+      </Checkbox>
+
+      <Show when={showAdvanced()}>
+        <div class="flex w-full flex-row gap-2">
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>Device model</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="iPhone14,5"
+                value={props.state.deviceModel}
+                onInput={e => props.setState('deviceModel', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>Language pack</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="ios"
+                value={props.state.langPack}
+                onInput={e => props.setState('langPack', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+        </div>
+        <div class="flex w-full flex-row gap-2">
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>System version</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="15.4"
+                value={props.state.systemVersion}
+                onInput={e => props.setState('systemVersion', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>App version</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="4.0.1"
+                value={props.state.appVersion}
+                onInput={e => props.setState('appVersion', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+        </div>
+        <div class="flex w-full flex-row gap-2">
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>System language code</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="en"
+                value={props.state.systemLangCode}
+                onInput={e => props.setState('systemLangCode', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+          <TextFieldRoot class="w-full">
+            <TextFieldLabel>Language code</TextFieldLabel>
+            <TextFieldFrame>
+              <TextField
+                placeholder="en"
+                value={props.state.langCode}
+                onInput={e => props.setState('langCode', e.currentTarget.value)}
+              />
+            </TextFieldFrame>
+          </TextFieldRoot>
+        </div>
+        <TextFieldRoot class="w-full">
+          <TextFieldLabel>Extra options (JSON)</TextFieldLabel>
+          <TextFieldFrame class="h-auto">
+            <TextField
+              as="textarea"
+              class="h-20 resize-none font-mono"
+              placeholder={'{"tz_offset": 3600}'}
+              value={props.state.extraJson}
+              onInput={e => props.setState('extraJson', e.currentTarget.value)}
+            />
+          </TextFieldFrame>
+        </TextFieldRoot>
+      </Show>
+    </div>
+  )
+}
+
+export function CustomApiDialog(props: {
+  visible: boolean
+  setVisible: (visible: boolean) => void
+  onSubmit: (options: CustomApiFields) => void
+}) {
+  const [state, setState] = useCustomApiFormState()
+
+  return (
+    <Dialog open={props.visible} onOpenChange={props.setVisible}>
+      <DialogContent class="flex flex-col gap-2">
+        <DialogHeader class="font-medium">
+          Custom connection options
+        </DialogHeader>
+        <CustomApiForm state={state} setState={setState} />
+
+        <Button
+          size="sm"
+          disabled={!state.apiId || !state.apiHash}
+          onClick={() => props.onSubmit(unwrap(state))}
+        >
+          Submit
+        </Button>
+      </DialogContent>
+    </Dialog>
+  )
+}
diff --git a/packages/repl/src/components/settings/login/Login.tsx b/packages/repl/src/components/settings/login/Login.tsx
index c55889b..ae5ac57 100644
--- a/packages/repl/src/components/settings/login/Login.tsx
+++ b/packages/repl/src/components/settings/login/Login.tsx
@@ -4,6 +4,7 @@ import { unknownToError } from '@fuman/utils'
 import { LucideChevronRight, LucideLockKeyhole, MessageSquareMore } from 'lucide-solid'
 import { workerInvoke, workerOn } from 'mtcute-repl-worker/client'
 import { createSignal, For, Match, onCleanup, onMount, Show, Switch } from 'solid-js'
+import { toast } from 'solid-sonner'
 import { Button } from '../../../lib/components/ui/button.tsx'
 import { OTPField, OTPFieldGroup, OTPFieldInput, OTPFieldSlot } from '../../../lib/components/ui/otp-field.tsx'
 import { Spinner } from '../../../lib/components/ui/spinner.tsx'
@@ -55,14 +56,18 @@ function QrLoginStep(props: StepProps<'qr'>) {
       cleanup2()
     })
 
-    const result = await workerInvoke('telegram', 'signInQr', {
-      accountId: props.accountId,
-      abortSignal: abortController.signal,
-    })
-    if (result === 'need_password') {
-      props.setStep('password')
-    } else {
-      props.setStep('done', { account: result })
+    try {
+      const result = await workerInvoke('telegram', 'signInQr', {
+        accountId: props.accountId,
+        abortSignal: abortController.signal,
+      })
+      if (result === 'need_password') {
+        props.setStep('password')
+      } else {
+        props.setStep('done', { account: result })
+      }
+    } catch (e) {
+      toast.error(unknownToError(e).message)
     }
   })
   onCleanup(() => abortController.abort())
diff --git a/packages/repl/src/lib/components/ui/text-field.tsx b/packages/repl/src/lib/components/ui/text-field.tsx
index 0c271b1..b4638bf 100644
--- a/packages/repl/src/lib/components/ui/text-field.tsx
+++ b/packages/repl/src/lib/components/ui/text-field.tsx
@@ -131,7 +131,7 @@ export function TextField<T extends ValidComponent = 'input'>(props: Polymorphic
 
   return (
     <TextFieldPrimitive.Input
-      class={cn('border-none outline-none placeholder:text-muted-foreground bg-transparent', local.class)}
+      class={cn('border-none outline-none placeholder:text-muted-foreground bg-transparent min-w-0 w-full', local.class)}
       {...rest}
     />
   )
diff --git a/packages/worker/src/client.ts b/packages/worker/src/client.ts
index 97f4e9b..555e12a 100644
--- a/packages/worker/src/client.ts
+++ b/packages/worker/src/client.ts
@@ -3,7 +3,7 @@ import type { ReplWorker } from './worker/main.ts'
 import type { ReplWorkerEvents } from './worker/utils.ts'
 import { Deferred, unknownToError } from '@fuman/utils'
 
-export type { TelegramAccount } from './store/accounts.ts'
+export type { CustomApiFields, TelegramAccount } from './store/accounts.ts'
 export type { StringSessionLibName } from './worker/telegram.ts'
 
 // eslint-disable-next-line ts/no-namespace
diff --git a/packages/worker/src/store/accounts.ts b/packages/worker/src/store/accounts.ts
index decbe87..5bcf419 100644
--- a/packages/worker/src/store/accounts.ts
+++ b/packages/worker/src/store/accounts.ts
@@ -9,6 +9,19 @@ export interface TelegramAccount {
   testMode: boolean
   telegramId: number
   dcId: number
+  apiOptions?: CustomApiFields
+}
+
+export interface CustomApiFields {
+  apiId: string
+  apiHash: string
+  deviceModel: string
+  systemVersion: string
+  appVersion: string
+  systemLangCode: string
+  langPack: string
+  langCode: string
+  extraJson: string
 }
 
 const AccountSchema = v.object({
@@ -19,6 +32,17 @@ const AccountSchema = v.object({
   name: v.string(),
   testMode: v.boolean(),
   dcId: v.number(),
+  apiOptions: v.object({
+    apiId: v.string(),
+    apiHash: v.string(),
+    deviceModel: v.string(),
+    systemVersion: v.string(),
+    appVersion: v.string(),
+    systemLangCode: v.string(),
+    langPack: v.string(),
+    langCode: v.string(),
+    extraJson: v.string(),
+  }).optional(),
 })
 
 export const $accounts = persistentAtom<TelegramAccount[]>('repl:accounts', [], {
diff --git a/packages/worker/src/utils/telegram.ts b/packages/worker/src/utils/telegram.ts
index a6b2804..2a3961e 100644
--- a/packages/worker/src/utils/telegram.ts
+++ b/packages/worker/src/utils/telegram.ts
@@ -1,17 +1,49 @@
-import type { InputStringSessionData } from '@mtcute/web/utils.js'
-import type { TelegramAccount } from '../store/accounts.ts'
+import type { tl } from '@mtcute/web'
+import type { CustomApiFields, TelegramAccount } from '../store/accounts.ts'
 import { asNonNull } from '@fuman/utils'
 import { BaseTelegramClient, IdbStorage, TransportError } from '@mtcute/web'
 import { getMe } from '@mtcute/web/methods.js'
+import { type InputStringSessionData, jsonToTlJson } from '@mtcute/web/utils.js'
 import { nanoid } from 'nanoid'
 
-export function createInternalClient(accountId: string, testMode?: boolean) {
+export function createInternalClient(
+  accountId: string,
+  testMode?: boolean,
+  apiOptions?: CustomApiFields,
+) {
+  let initConnectionOptions: Partial<tl.RawInitConnectionRequest> | undefined
+  if (apiOptions) {
+    initConnectionOptions = {}
+    if (apiOptions.deviceModel) {
+      initConnectionOptions.deviceModel = apiOptions.deviceModel
+    }
+    if (apiOptions.systemVersion) {
+      initConnectionOptions.systemVersion = apiOptions.systemVersion
+    }
+    if (apiOptions.appVersion) {
+      initConnectionOptions.appVersion = apiOptions.appVersion
+    }
+    if (apiOptions.langCode) {
+      initConnectionOptions.langCode = apiOptions.langCode
+    }
+    if (apiOptions.langPack) {
+      initConnectionOptions.langPack = apiOptions.langPack
+    }
+    if (apiOptions.systemLangCode) {
+      initConnectionOptions.systemLangCode = apiOptions.systemLangCode
+    }
+    if (apiOptions.extraJson) {
+      initConnectionOptions.params = jsonToTlJson(JSON.parse(apiOptions.extraJson))
+    }
+  }
+
   return new BaseTelegramClient({
-    apiId: Number(import.meta.env.VITE_API_ID),
-    apiHash: import.meta.env.VITE_API_HASH,
+    apiId: Number(apiOptions?.apiId ?? import.meta.env.VITE_API_ID),
+    apiHash: apiOptions?.apiHash ?? import.meta.env.VITE_API_HASH,
     storage: new IdbStorage(`mtcute:${accountId}`),
     testMode,
     logLevel: import.meta.env.DEV ? 5 : 2,
+    initConnectionOptions,
   })
 }
 
diff --git a/packages/worker/src/worker/telegram.ts b/packages/worker/src/worker/telegram.ts
index 11c589f..90ed416 100644
--- a/packages/worker/src/worker/telegram.ts
+++ b/packages/worker/src/worker/telegram.ts
@@ -1,6 +1,6 @@
 import type { BaseTelegramClient, SentCode, User } from '@mtcute/web'
 import type { StringSessionData } from '@mtcute/web/utils.js'
-import type { TelegramAccount } from '../store/accounts.ts'
+import type { CustomApiFields, TelegramAccount } from '../store/accounts.ts'
 import { assert, hex } from '@fuman/utils'
 import { DC_MAPPING_PROD, DC_MAPPING_TEST } from '@mtcute/convert'
 import { tl } from '@mtcute/web'
@@ -31,7 +31,9 @@ function getClient(accountId: string) {
 function getTmpClient(accountId: string): [BaseTelegramClient, () => Promise<void>] {
   const client = clients.get(accountId)
   if (!client) {
-    const tmpClient = createInternalClient(accountId)
+    const accountInfo = $accounts.get().find(it => it.id === accountId)
+    if (!accountInfo) throw new Error('Account not found')
+    const tmpClient = createInternalClient(accountId, accountInfo.testMode, accountInfo.apiOptions)
     return [tmpClient, () => tmpClient.close()]
   } else {
     return [client, () => Promise.resolve()]
@@ -73,8 +75,9 @@ export class ReplWorkerTelegram {
   async createClient(params: {
     accountId: string
     testMode?: boolean
+    apiOptions?: CustomApiFields
   }) {
-    const client = createInternalClient(params.accountId, params.testMode)
+    const client = createInternalClient(params.accountId, params.testMode, params.apiOptions)
     clients.set(params.accountId, client)
   }