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Learn who can start and view Expo Simulators sessions, how to protect session tokens and preview links, and how long Expo Simulators keeps recordings, screenshots, and logs.

Expo Simulators is a limited-access preview. It is not included with paid or free plans and is currently available only to select partners. Join the waitlist if you are interested in trying it.

An Expo Simulators session belongs to an Expo Services project. Account roles control who can start, view, and stop sessions. Session tokens and preview links give direct access to the remote device, so treat them as secrets.

For how long Expo Simulators keeps job logs and artifacts, see Retention and deletion.

For how the parts connect, see Expo Simulators security model.

Permissions

Read access to a session includes its connection details while the session runs. A member with the View Only role can read the controller tokens of a running session through the REST API or the Expo GraphQL API.

For automation, create a robot user with the Developer role. Developer is the minimum role that can create and stop sessions.

If the user who started a session is deleted, Expo Simulators stops the session.

Session tokens

The connection details of a session include tokens for the controller. Expo Simulators stores the connection details encrypted.

The REST API returns remoteConfig only while the session is in-progress. After the session stops or fails, remoteConfig is null. EAS CLI (eas simulator:get) and the Expo GraphQL API still return the stored connection details after the session stops. By then, the remote device and its controller endpoints no longer exist. Session responses include Cache-Control: private, no-store and Pragma: no-cache.

The session page on expo.dev masks the token values by default. Anyone who can view the session page can reveal or copy them.

Browser preview links

A private link has this format:

https://expo.dev/accounts/<account>/projects/<project>/simulator-sessions/<session-id>/preview

A public link contains the preview token. Treat a public link as a secret. Anyone with the link can see and use the simulator while the session runs. Share it only with the people who need it, and set a maximum duration on the session.

A session with private links still has a preview token. The REST API returns it as webPreviewToken to any member who can read the session. Keep the preview token secret, even when the session uses private links. Anyone who has the token can make a public link.

If a session starts with --frame-ancestor or --cors-origin, EAS CLI prints the preview host URL with the preview token. For a session that you create with frameAncestors or corsOrigins, the REST API returns the URL as previewApiUrl and the token as webPreviewToken. Web pages on the allowed origins use the token to show the session. Anyone who can read such a page can get the token and control the device. See Show an Expo Simulators session on your own web page.

Network access

• Metro tunnel: a Metro URL from npx expo start --tunnel is public while the tunnel runs. It does not require authentication. Stop Metro when you finish.
• Default egress: without local egress, all traffic from the simulator exits from Expo infrastructure.
• Local egress: with --egress local, device traffic exits from your computer: all TCP traffic on Android, and traffic that honors the system proxy on iOS. The egress client refuses local, private, link-local, and multicast addresses. Only the exact host:port entries that you pass with --egress-allow are exceptions.

See Network traffic and local egress in Expo Simulators.

Data that Expo Simulators stores

One artifact can be up to about 5 GiB.

Expo Simulators records the request origin and agent identifiers that a client sends when it creates a session. Expo Simulators uses these values for analytics only, not for authorization.

Artifact downloads

eas simulator:get --json returns a downloadUrl for each artifact. The download URL contains a long random key and does not require authentication. Treat it as a secret.

The downloadUrl does not change. Each request to it redirects to a new signed storage URL, which expires after one hour. To download the artifact again later, request the same downloadUrl again.

Retention and deletion

• Job logs on the session page are available for 30 days after the session is created.
• Expo Simulators keeps session artifacts, such as screenshots and recordings, until you delete the session.
• You can delete a session after it finishes. You cannot delete a running session.
• When you delete a session, Expo Simulators also deletes its recordings and screenshots. You cannot undo this.
• When you delete the project, Expo Simulators also deletes its sessions and their artifacts.

Common questions