diff --git a/backend/src/modules/rate_limit/routes.py b/backend/src/modules/rate_limit/routes.py
index 3556282f..a043e241 100644
--- a/backend/src/modules/rate_limit/routes.py
+++ b/backend/src/modules/rate_limit/routes.py
@@ -32,11 +32,15 @@
 
            Results are paginated to handle systems with many rate limit configurations.
            """,
-    responses={401: {"description": "Not authenticated"}},
+    responses={
+        401: {"description": "Not authenticated"},
+        403: {"description": "Not a superuser"},
+    },
     response_description="A paginated list of rate limits with their configuration details",
 )
 async def get_rate_limits(
     db: AsyncSessionDep,
+    _: CurrentSuperUserDep,
     rate_limit_service: RateLimitServiceDep,
     page: int = 1,
     items_per_page: int = 10,
@@ -76,12 +80,17 @@ async def get_rate_limits(
 
            Rate limit names are typically in the format of `path:limit:period`.
            """,
-    responses={401: {"description": "Not authenticated"}, 404: {"description": "Rate limit not found"}},
+    responses={
+        401: {"description": "Not authenticated"},
+        403: {"description": "Not a superuser"},
+        404: {"description": "Rate limit not found"},
+    },
     response_description="Detailed configuration of the requested rate limit",
 )
 async def get_rate_limit(
     name: str,
     db: AsyncSessionDep,
+    _: CurrentSuperUserDep,
     rate_limit_service: RateLimitServiceDep,
 ) -> dict[str, Any] | None:
     """
diff --git a/backend/src/modules/tier/routes.py b/backend/src/modules/tier/routes.py
index 9613b96c..8bd5dbdc 100644
--- a/backend/src/modules/tier/routes.py
+++ b/backend/src/modules/tier/routes.py
@@ -4,7 +4,7 @@
 from fastcrud import PaginatedListResponse, compute_offset, paginated_response
 
 from ...infrastructure.auth.http_exceptions import NotFoundException
-from ...infrastructure.dependencies import AsyncSessionDep
+from ...infrastructure.dependencies import AsyncSessionDep, CurrentUserDep
 from ..common.exceptions import TierNotFoundError
 from ..common.utils.error_handler import handle_exception
 from .dependencies import TierServiceDep
@@ -13,14 +13,20 @@
 router = APIRouter(tags=["Tiers"])
 
 
-@router.get("/", response_model=PaginatedListResponse[TierRead], summary="List tiers")
+@router.get(
+    "/",
+    response_model=PaginatedListResponse[TierRead],
+    summary="List tiers",
+    responses={401: {"description": "Not authenticated"}},
+)
 async def get_tiers(
     db: AsyncSessionDep,
+    _: CurrentUserDep,
     tier_service: TierServiceDep,
     page: int = 1,
     items_per_page: int = 10,
 ) -> dict:
-    """Paginated list of tiers."""
+    """Paginated list of tiers (authenticated)."""
     try:
         tiers_data = await tier_service.get_all(
             db=db,
@@ -35,13 +41,22 @@ async def get_tiers(
         raise HTTPException(status_code=500, detail="An unexpected error occurred")
 
 
-@router.get("/{name}", response_model=TierRead, summary="Get a tier by name")
+@router.get(
+    "/{name}",
+    response_model=TierRead,
+    summary="Get a tier by name",
+    responses={
+        401: {"description": "Not authenticated"},
+        404: {"description": "Tier not found"},
+    },
+)
 async def get_tier_by_name(
     name: str,
     db: AsyncSessionDep,
+    _: CurrentUserDep,
     tier_service: TierServiceDep,
 ) -> dict[str, Any]:
-    """Get a tier by name."""
+    """Get a tier by name (authenticated)."""
     try:
         return await tier_service.get_by_name(name, db)
     except TierNotFoundError:
diff --git a/backend/src/modules/user/routes.py b/backend/src/modules/user/routes.py
index e9265cf4..e890ad27 100644
--- a/backend/src/modules/user/routes.py
+++ b/backend/src/modules/user/routes.py
@@ -13,6 +13,7 @@
 from .dependencies import UserServiceDep
 from .schemas import (
     UserCreate,
+    UserProfileRead,
     UserRead,
     UserTierUpdate,
     UserUpdate,
@@ -117,22 +118,23 @@ async def get_current_user_profile(
 
 @router.get(
     "/{username}",
-    response_model=UserRead,
+    response_model=UserProfileRead,
     summary="Get User Profile by Username",
     description="""
-            Retrieves a user's profile information by their unique username.
+            Retrieves a user's public profile by their unique username.
 
-            This endpoint can be used to look up any active user in the system by their
-            username. It returns the same profile data structure as other user
-            endpoints but does not include sensitive information.
+            Any signed-in user can look up any other active user. The response carries
+            the display fields only - no email address - so the lookup can't be used to
+            collect addresses. Read your own full record from `/users/me`.
 
             Note that usernames are case-sensitive in lookup operations.
             """,
-    responses={404: {"description": "User not found"}},
+    responses={401: {"description": "Not authenticated"}, 404: {"description": "User not found"}},
     response_description="The requested user's profile data",
 )
 async def get_user_by_username(
     username: str,
+    _: CurrentUserDep,
     db: AsyncSessionDep,
     user_service: UserServiceDep,
 ) -> dict[str, Any]:
diff --git a/backend/src/modules/user/schemas.py b/backend/src/modules/user/schemas.py
index 2a1754fc..35bb3664 100644
--- a/backend/src/modules/user/schemas.py
+++ b/backend/src/modules/user/schemas.py
@@ -43,6 +43,24 @@ class User(TimestampSchema, UserBase, PersistentDeletion):
     oauth_updated_at: datetime | None = None
 
 
+class UserProfileRead(BaseModel):
+    """Another user's profile: the fields any signed-in user may see.
+
+    No email address, so looking someone up by username can't be used to collect
+    addresses. The owner reads their own record through ``/users/me``, and a
+    superuser through the list and active-and-inactive endpoints.
+    """
+
+    id: int
+    name: Annotated[str, Field(min_length=2, max_length=30, examples=["User Userson"])]
+    username: Annotated[
+        str,
+        Field(min_length=2, max_length=20, pattern=r"^[a-z0-9]+$", examples=["userson"]),
+    ]
+    profile_image_url: str
+    tier_id: int | None = None
+
+
 class UserRead(BaseModel):
     """Schema for reading user data, excludes sensitive information."""
 
diff --git a/backend/tests/integration/api/v1/test_read_endpoint_auth.py b/backend/tests/integration/api/v1/test_read_endpoint_auth.py
new file mode 100644
index 00000000..94ac270b
--- /dev/null
+++ b/backend/tests/integration/api/v1/test_read_endpoint_auth.py
@@ -0,0 +1,68 @@
+"""Who may read the tier and rate-limit endpoints."""
+
+import pytest
+from httpx import AsyncClient
+
+pytestmark = pytest.mark.asyncio
+
+ANONYMOUS_READS = [
+    "/api/v1/users/",
+    "/api/v1/tiers/",
+    "/api/v1/rate-limits/",
+]
+
+
+@pytest.mark.parametrize("path", ANONYMOUS_READS)
+async def test_read_endpoints_reject_anonymous_callers(client: AsyncClient, path: str):
+    """None of the collection reads answer without a session."""
+    response = await client.get(path)
+
+    assert response.status_code == 401
+
+
+async def test_named_reads_reject_anonymous_callers(client: AsyncClient, test_tier: dict):
+    """The by-name lookups are gated too, before the row is even looked up."""
+    assert (await client.get(f"/api/v1/tiers/{test_tier['name']}")).status_code == 401
+    assert (await client.get("/api/v1/rate-limits/anything")).status_code == 401
+
+
+async def test_tiers_are_readable_by_any_signed_in_user(auth_client: AsyncClient, test_tier: dict):
+    """Tiers describe what a plan offers, so any signed-in user may read them."""
+    listing = await auth_client.get("/api/v1/tiers/")
+    named = await auth_client.get(f"/api/v1/tiers/{test_tier['name']}")
+
+    assert listing.status_code == 200
+    assert named.status_code == 200
+    assert named.json()["name"] == test_tier["name"]
+
+
+async def test_rate_limit_configuration_is_superuser_only(auth_client: AsyncClient):
+    """Rate-limit rows are operational configuration, not user-facing data."""
+    assert (await auth_client.get("/api/v1/rate-limits/")).status_code == 403
+    assert (await auth_client.get("/api/v1/rate-limits/anything")).status_code == 403
+
+
+async def test_rate_limits_are_readable_by_a_superuser(superuser_auth_client: AsyncClient):
+    """A superuser reads the same rows that PATCH and DELETE already required one for."""
+    response = await superuser_auth_client.get("/api/v1/rate-limits/")
+
+    assert response.status_code == 200
+    assert "data" in response.json()
+
+
+@pytest.mark.parametrize(
+    ("path", "method", "expected"),
+    [
+        ("/api/v1/users/{username}", "get", {"401", "404"}),
+        ("/api/v1/tiers/", "get", {"401"}),
+        ("/api/v1/tiers/{name}", "get", {"401", "404"}),
+        ("/api/v1/rate-limits/", "get", {"401", "403"}),
+        ("/api/v1/rate-limits/{name}", "get", {"401", "403", "404"}),
+    ],
+)
+async def test_openapi_advertises_the_gate(client: AsyncClient, path: str, method: str, expected: set[str]):
+    """A client generated from the schema must know these can be refused."""
+    schema = (await client.get("/openapi.json")).json()
+    operation = schema["paths"][path][method]
+
+    assert expected <= set(operation["responses"])
diff --git a/backend/tests/integration/api/v1/users/test_read.py b/backend/tests/integration/api/v1/users/test_read.py
index f192d573..7aa1c560 100644
--- a/backend/tests/integration/api/v1/users/test_read.py
+++ b/backend/tests/integration/api/v1/users/test_read.py
@@ -20,8 +20,8 @@ async def test_get_user_by_username_success(auth_client: AsyncClient, db_session
     data = response.json()
     assert data["username"] == username
     assert "id" in data
-    assert "email" in data
     assert "name" in data
+    assert "email" not in data
 
 
 async def test_get_user_by_username_not_found(auth_client: AsyncClient, db_session: AsyncSession):
@@ -99,3 +99,25 @@ async def test_get_user_rate_limits(auth_client: AsyncClient, db_session: AsyncS
     assert response.status_code == 200
     data = response.json()
     assert "rate_limits" in data
+
+
+async def test_get_user_by_username_requires_authentication(client: AsyncClient, test_user: dict):
+    """An anonymous caller can't look anyone up by username."""
+    response = await client.get(f"/api/v1/users/{test_user['username']}")
+
+    assert response.status_code == 401
+
+
+async def test_profile_lookup_never_carries_an_email(auth_client: AsyncClient, test_user_2: dict, db_session: AsyncSession):
+    """Looking someone else up returns display fields, never their address.
+
+    Registration is open, so anything this endpoint returns is readable by anyone
+    willing to sign up; an email address here would be a directory of addresses.
+    """
+    response = await auth_client.get(f"/api/v1/users/{test_user_2['username']}")
+
+    assert response.status_code == 200
+    data = response.json()
+    assert data["username"] == test_user_2["username"]
+    assert "email" not in data
+    assert "is_superuser" not in data
diff --git a/backend/tests/integration/api/v1/users/test_update.py b/backend/tests/integration/api/v1/users/test_update.py
index d6ce6337..cc0d7aab 100644
--- a/backend/tests/integration/api/v1/users/test_update.py
+++ b/backend/tests/integration/api/v1/users/test_update.py
@@ -4,6 +4,8 @@
 from httpx import AsyncClient
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from src.modules.user.models import User
+
 from .test_create import generate_unique_user_data
 
 logging.basicConfig(level=logging.INFO)
@@ -35,11 +37,10 @@ async def test_update_user_profile_success(
     assert "message" in data
     assert data["message"] == "User updated successfully"
 
-    get_response = await auth_client.get(f"/api/v1/users/{username}")
-    assert get_response.status_code == 200
-    user_data = get_response.json()
-    assert user_data["name"] == update_data["name"]
-    assert user_data["email"] == update_data["email"]
+    stored = await db_session.get(User, test_user["id"])
+    await db_session.refresh(stored)
+    assert stored.name == update_data["name"]
+    assert stored.email == update_data["email"]
 
 
 async def test_update_user_profile_invalid_email(
diff --git a/docs/user-guide/api/index.md b/docs/user-guide/api/index.md
index e8f56250..d3645693 100644
--- a/docs/user-guide/api/index.md
+++ b/docs/user-guide/api/index.md
@@ -182,9 +182,9 @@ What ships out of the box (40 total routes):
 
 | Prefix | Source | Notes |
 |--------|--------|-------|
-| `POST/GET/PATCH/DELETE /api/v1/users/*` | `modules/user/routes.py` | Open create, session/superuser-gated reads/updates |
-| `GET /api/v1/tiers/*` | `modules/tier/routes.py` | Public list + lookup by name |
-| `GET/PATCH/DELETE /api/v1/rate-limits/*` | `modules/rate_limit/routes.py` | List/get public; PATCH/DELETE require superuser |
+| `POST/GET/PATCH/DELETE /api/v1/users/*` | `modules/user/routes.py` | Open create; reads/updates need a session, and a lookup by username returns no email |
+| `GET /api/v1/tiers/*` | `modules/tier/routes.py` | Authenticated list + lookup by name |
+| `GET/PATCH/DELETE /api/v1/rate-limits/*` | `modules/rate_limit/routes.py` | Superuser only |
 | `POST /api/v1/auth/login`, `logout`, `logout-all`, `refresh-csrf`, `check-auth` | `infrastructure/auth/routes.py` | Session auth |
 | `GET /api/v1/auth/oauth/google`, `oauth/callback/google` | `infrastructure/auth/routes.py` | Google OAuth |
 | `POST/GET/PATCH/DELETE /api/v1/api-keys/*` | `modules/api_keys/routes.py` | Authenticated key management |
diff --git a/docs/user-guide/authentication/user-management.md b/docs/user-guide/authentication/user-management.md
index 12e80a69..ac10afb3 100644
--- a/docs/user-guide/authentication/user-management.md
+++ b/docs/user-guide/authentication/user-management.md
@@ -11,7 +11,7 @@ All under `/api/v1/users/` (defined in `modules/user/routes.py`):
 | `POST` | `/api/v1/users/` | Create a new user | Open |
 | `GET` | `/api/v1/users/` | Paginated list of users | Superuser |
 | `GET` | `/api/v1/users/me` | Current user's profile | Session |
-| `GET` | `/api/v1/users/{username}` | Get a user by username (active only) | Open |
+| `GET` | `/api/v1/users/{username}` | Public profile by username (no email) | Session |
 | `GET` | `/api/v1/users/active-and-inactive/{username}` | Same as above, includes soft-deleted | Superuser |
 | `PATCH` | `/api/v1/users/{username}` | Update profile (own or admin) | Session |
 | `DELETE` | `/api/v1/users/{username}` | Soft-delete a user (own or admin) | Session |