Expo Simulators lets agents test iOS apps without a local Mac and record the run

Expo made Expo Simulators generally available to paid subscribers on November 12. The service runs an iOS simulator or Android emulator in the cloud so coding agents can open a mobile build, interact with it and leave a recording for review. A developer working from Linux or Windows can inspect an iOS run without keeping a local Mac available for the simulator.

Expo still described the service as a limited beta in a case study verified on October 29. It now lists access on its Starter, Production and Enterprise plans. A coding agent or a continuous integration job can start a run. A teammate can follow it in a browser, giving designers and product managers a way to see what changed while the build is still running.

What a reviewer gets after a run

A session page keeps the recording, screenshots and logs. A screenshot can show whether a button is clipped. Video can show how a menu responds to a swipe. An activity record can show which controls the agent used and in what order. The app’s own logs serve a different purpose, such as showing an error the app printed at the time of a failed step.

Expo’s documentation says a recording may miss individual frames, which limits its use for diagnosing a brief stutter. In an example published by Expo, an agent tried an app at the largest text setting, found labels that overlapped and attached before-and-after images to the proposed change. Those images give a reviewer a way to inspect the layout at that setting.

The way a team shares that evidence affects who can see it. Project access is required for the session page, according to Expo’s documentation. A direct download link for a file works without an Expo login. Expo keeps job logs for 30 days from session creation. Expo’s pricing table lists 30 days of retention for session artifacts. Its technical documentation says recordings and screenshots are kept until the session is deleted.

Separate devices for simultaneous checks

Each session gets its own virtual machine. If one agent reinstalls an app, it does so in its own environment, so another agent can keep testing its build. Sessions draw on the account’s concurrent job allowance. Once the available slots are occupied, new sessions wait in a queue. The recordings and logs from the parallel runs are attached to their respective sessions.

Support extends to native iOS and Android apps, Flutter and Unity as well as Expo and React Native. The build still has to target the simulator or emulator. An iOS package built for a physical iPhone, for instance, cannot be installed on the simulator. General controls such as taps and text entry are available across frameworks. React Native’s Fast Refresh, which applies code changes to a running development build, requires a React Native app and its development server.

The recording shows the code the installed build actually loaded. A React Native release build carries the JavaScript packaged when it was built. Relaunching that same build can replay an old version of the app after its source has changed. A development build can load current code from the development server, so the build a reviewer sees matters when comparing the recording with the proposed change.

Expo lists the same usage price for iOS and Android at 10 cents per simulator minute, in addition to the subscription. The company says its eligible plans include 60 minutes a month until 2027. If a team runs an iOS and an Android session for 10 minutes each, those runs use 20 simulator minutes even if they finish together.

Paid sessions can run for up to 115 minutes after the device is ready. Teams can choose a shorter maximum or set an idle limit. A simulator may keep running after the CI job that started it exits. When the session ends, Expo closes the connection used to control the device and keeps the recording and screenshots available for review.