diff --git a/backend/app/cli.py b/backend/app/cli.py
index 2a870fa..65ae74d 100644
--- a/backend/app/cli.py
+++ b/backend/app/cli.py
@@ -7,6 +7,7 @@ created by an operator running this script directly on the app server.
 import argparse
 import asyncio
 import base64
+import getpass
 
 from pydantic import ValidationError
 
@@ -15,6 +16,15 @@ from app.schemas.user import UserCreate
 from app.services.auth_service import DuplicateUserError, register_user
 
 
+def _prompt_password() -> str:
+    while True:
+        password = getpass.getpass("Password: ")
+        confirm = getpass.getpass("Confirm password: ")
+        if password == confirm:
+            return password
+        print("Passwords didn't match -- try again.")
+
+
 async def _create_user(username: str, email: str, password: str, is_admin: bool) -> None:
     try:
         data = UserCreate(username=username, email=email, password=password)
@@ -69,7 +79,12 @@ def main() -> None:
     create_user = subparsers.add_parser("create-user", help="Create a new user account")
     create_user.add_argument("username")
     create_user.add_argument("email")
-    create_user.add_argument("password")
+    create_user.add_argument(
+        "password",
+        nargs="?",
+        default=None,
+        help="If omitted, you'll be prompted interactively (hidden input, entered twice to confirm).",
+    )
     create_user.add_argument("--admin", action="store_true", help="Grant is_site_admin")
 
     subparsers.add_parser("generate-vapid-keys", help="Generate a VAPID key pair for push notifications")
@@ -77,7 +92,8 @@ def main() -> None:
     args = parser.parse_args()
 
     if args.command == "create-user":
-        asyncio.run(_create_user(args.username, args.email, args.password, args.admin))
+        password = args.password if args.password is not None else _prompt_password()
+        asyncio.run(_create_user(args.username, args.email, password, args.admin))
     elif args.command == "generate-vapid-keys":
         _generate_vapid_keys()
 
diff --git a/backend/app/schemas/site_invite.py b/backend/app/schemas/site_invite.py
index 82017a6..4fd02da 100644
--- a/backend/app/schemas/site_invite.py
+++ b/backend/app/schemas/site_invite.py
@@ -1,7 +1,7 @@
 import uuid
 from datetime import datetime
 
-from pydantic import BaseModel, ConfigDict, EmailStr, Field
+from pydantic import BaseModel, ConfigDict, EmailStr, Field, model_validator
 
 from app.models import InviteStatus
 
@@ -29,3 +29,15 @@ class SignupComplete(BaseModel):
     token: str
     username: str = Field(min_length=3, max_length=50)
     password: str = Field(min_length=8, max_length=200)
+    password_confirm: str
+
+    # Backend backstop -- the signup form does its own client-side match
+    # check for immediate feedback (see SignupPage.tsx), but account
+    # creation is irreversible enough (a typo'd password with no recovery
+    # path until forgot-password) that the guarantee shouldn't rely on the
+    # client alone.
+    @model_validator(mode="after")
+    def _passwords_match(self) -> "SignupComplete":
+        if self.password != self.password_confirm:
+            raise ValueError("Passwords don't match")
+        return self
diff --git a/backend/tests/test_cli.py b/backend/tests/test_cli.py
new file mode 100644
index 0000000..c09b42e
--- /dev/null
+++ b/backend/tests/test_cli.py
@@ -0,0 +1,78 @@
+import uuid
+
+import pytest
+import pytest_asyncio
+from sqlalchemy import select
+
+from app.cli import _create_user, _prompt_password
+from app.database import async_session_factory
+from app.database import engine as _cli_engine
+from app.models import User
+
+
+def _unique(prefix: str) -> str:
+    return f"{prefix}-{uuid.uuid4().hex[:8]}"
+
+
+@pytest_asyncio.fixture(autouse=True)
+async def _dispose_cli_engine_between_tests():
+    # _create_user (like the real CLI) uses app.database's module-level
+    # engine directly, not the db_session fixture's own per-test engine --
+    # pytest-asyncio gives each test function a fresh event loop by
+    # default, and a pooled connection opened on a since-closed loop
+    # produces asyncpg "another operation is in progress" errors if reused
+    # by a later test. Disposing after every test forces a fresh connection
+    # next time instead of reusing a stale one.
+    yield
+    await _cli_engine.dispose()
+
+
+async def _get_user(username: str) -> User | None:
+    async with async_session_factory() as session:
+        result = await session.execute(select(User).where(User.username == username))
+        return result.scalar_one_or_none()
+
+
+def test_prompt_password_matches_on_first_try(monkeypatch):
+    responses = iter(["correct-horse", "correct-horse"])
+    monkeypatch.setattr("getpass.getpass", lambda prompt="": next(responses))
+
+    assert _prompt_password() == "correct-horse"
+
+
+def test_prompt_password_retries_on_mismatch(monkeypatch, capsys):
+    responses = iter(["typo-password", "correct-password", "correct-password", "correct-password"])
+    monkeypatch.setattr("getpass.getpass", lambda prompt="": next(responses))
+
+    assert _prompt_password() == "correct-password"
+    assert "didn't match" in capsys.readouterr().out
+
+
+async def test_create_user_with_explicit_password_succeeds():
+    username = _unique("alice")
+    await _create_user(username, f"{username}@example.com", "password123", False)
+
+    user = await _get_user(username)
+    assert user is not None
+    assert user.is_site_admin is False
+
+
+async def test_create_user_via_prompted_password(monkeypatch):
+    responses = iter(["prompted-pass", "prompted-pass"])
+    monkeypatch.setattr("getpass.getpass", lambda prompt="": next(responses))
+
+    username = _unique("bob")
+    password = _prompt_password()
+    await _create_user(username, f"{username}@example.com", password, True)
+
+    user = await _get_user(username)
+    assert user is not None
+    assert user.is_site_admin is True
+
+
+async def test_create_user_rejects_short_password():
+    username = _unique("shortpw")
+    with pytest.raises(SystemExit):
+        await _create_user(username, f"{username}@example.com", "short", False)
+
+    assert await _get_user(username) is None
diff --git a/backend/tests/test_site_invites.py b/backend/tests/test_site_invites.py
index b6c5fa6..be35958 100644
--- a/backend/tests/test_site_invites.py
+++ b/backend/tests/test_site_invites.py
@@ -70,7 +70,7 @@ async def test_signup_flow_end_to_end(client, db_session, monkeypatch):
 
     complete = await client.post(
         "/api/signup",
-        json={"token": token, "username": "newperson", "password": "password123"},
+        json={"token": token, "username": "newperson", "password": "password123", "password_confirm": "password123"},
     )
     assert complete.status_code == 200, complete.text
     assert complete.json()["email"] == "newperson@example.com"
@@ -80,6 +80,32 @@ async def test_signup_flow_end_to_end(client, db_session, monkeypatch):
     assert me.json()["username"] == "newperson"
 
 
+async def test_signup_rejects_mismatched_password_confirmation(client, db_session, monkeypatch):
+    calls = _fake_smtp(monkeypatch)
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+    await _configure_smtp(client)
+
+    await client.post("/api/admin/invites", json={"email": "typo@example.com"})
+    token = _extract_token(calls[0]["message"].get_content())
+
+    complete = await client.post(
+        "/api/signup",
+        json={
+            "token": token,
+            "username": "typouser",
+            "password": "password123",
+            "password_confirm": "password124",
+        },
+    )
+    assert complete.status_code == 422
+
+    # The mismatch must not have consumed the invite -- a typo shouldn't
+    # burn a single-use token.
+    validate = await client.get(f"/api/signup/validate?token={token}")
+    assert validate.status_code == 200
+
+
 async def test_invalid_token_rejected(client, db_session):
     await register_and_login(client, db_session, username="alice")
 
@@ -88,7 +114,7 @@ async def test_invalid_token_rejected(client, db_session):
 
     complete = await client.post(
         "/api/signup",
-        json={"token": "not-a-real-token", "username": "someone", "password": "password123"},
+        json={"token": "not-a-real-token", "username": "someone", "password": "password123", "password_confirm": "password123"},
     )
     assert complete.status_code == 400
 
@@ -109,7 +135,7 @@ async def test_expired_token_rejected(client, db_session, monkeypatch):
 
     complete = await client.post(
         "/api/signup",
-        json={"token": token, "username": "late", "password": "password123"},
+        json={"token": token, "username": "late", "password": "password123", "password_confirm": "password123"},
     )
     assert complete.status_code == 400
 
@@ -125,13 +151,13 @@ async def test_used_token_cannot_be_reused(client, db_session, monkeypatch):
 
     first = await client.post(
         "/api/signup",
-        json={"token": token, "username": "onceuser", "password": "password123"},
+        json={"token": token, "username": "onceuser", "password": "password123", "password_confirm": "password123"},
     )
     assert first.status_code == 200
 
     second = await client.post(
         "/api/signup",
-        json={"token": token, "username": "onceuser2", "password": "password123"},
+        json={"token": token, "username": "onceuser2", "password": "password123", "password_confirm": "password123"},
     )
     assert second.status_code == 400
 
@@ -152,7 +178,7 @@ async def test_revoke_site_invite_prevents_signup(client, db_session, monkeypatc
 
     complete = await client.post(
         "/api/signup",
-        json={"token": token, "username": "revokeduser", "password": "password123"},
+        json={"token": token, "username": "revokeduser", "password": "password123", "password_confirm": "password123"},
     )
     assert complete.status_code == 400
 
diff --git a/frontend/src/api/signup.ts b/frontend/src/api/signup.ts
index e7a6a10..1ecbcdd 100644
--- a/frontend/src/api/signup.ts
+++ b/frontend/src/api/signup.ts
@@ -9,9 +9,10 @@ export function completeSignup(
   token: string,
   username: string,
   password: string,
+  passwordConfirm: string,
 ): Promise<User> {
   return apiFetch<User>('/api/signup', {
     method: 'POST',
-    body: JSON.stringify({ token, username, password }),
+    body: JSON.stringify({ token, username, password, password_confirm: passwordConfirm }),
   })
 }
diff --git a/frontend/src/pages/SignupPage.tsx b/frontend/src/pages/SignupPage.tsx
index c517682..61acdeb 100644
--- a/frontend/src/pages/SignupPage.tsx
+++ b/frontend/src/pages/SignupPage.tsx
@@ -18,6 +18,7 @@ export function SignupPage() {
 
   const [username, setUsername] = useState('')
   const [password, setPassword] = useState('')
+  const [passwordConfirm, setPasswordConfirm] = useState('')
   const [error, setError] = useState<string | null>(null)
   const [submitting, setSubmitting] = useState(false)
 
@@ -40,9 +41,13 @@ export function SignupPage() {
   async function handleSubmit(e: FormEvent) {
     e.preventDefault()
     setError(null)
+    if (password !== passwordConfirm) {
+      setError("Passwords don't match")
+      return
+    }
     setSubmitting(true)
     try {
-      const newUser = await completeSignup(token, username, password)
+      const newUser = await completeSignup(token, username, password, passwordConfirm)
       updateUser(newUser)
       navigate('/rooms')
     } catch (err) {
@@ -92,6 +97,18 @@ export function SignupPage() {
                   onChange={(e) => setPassword(e.target.value)}
                   required
                   minLength={8}
+                  autoComplete="new-password"
+                />
+              </label>
+              <label>
+                Confirm password
+                <input
+                  type="password"
+                  value={passwordConfirm}
+                  onChange={(e) => setPasswordConfirm(e.target.value)}
+                  required
+                  minLength={8}
+                  autoComplete="new-password"
                 />
               </label>
               {error && <p className="login-error">{error}</p>}