---
title: Isolation | Avara
description: How Express keeps tenants apart — admins see everything; members see only the customers they belong to, never unattached studies.
---

Express isolation is membership plus a label on the study. There is no second channel. A member of one customer cannot see another customer’s studies. Unattached studies never leak to members.

Each study may carry an `expressCustomerId` (`cus_…`). Each user is either an **admin** (hosting-company staff) or a **member** (everyone else), and members are added to zero or more Express customers.

## Who sees what

\| Role | Studies with an Express customer they belong to | Studies for an Express customer they do **not** belong to | Studies with **no** Express customer | |---|---|---|---| | **Admin** | Yes | Yes | Yes | | **Member** | Yes | No | No |

**Admins** see every study in the organization, including studies with no Express customer attached. Reserve admin for your staff. Do not grant it to end-customer users.

**Members** see a study only if they belong to that study’s Express customer. They never see studies tagged with a customer they are not in. They never see studies with no `expressCustomerId`.

## No leakage

- Customer A’s members cannot see customer B’s studies.
- A member who belongs to several customers sees the **union** of those customers’ studies only — still not other tenants, still not unattached studies.
- Creating a study without `expressCustomerId` hides it from every member. Admins still see it. That is by design, not a way to share work across tenants.

Attach the customer on [study create](/integration/express/studies/index.md). Add the people who should see that tenant on [Users](/integration/express/users/index.md).