1d ago

Codex adds multi-viewport testing to in-app browser

0

Codex enables its in-app browser to test applications across multiple viewport sizes and breakpoints. The system controls the device toolbar and automatically navigates through the app at different dimensions. For extended runs it captures screenshots at key moments. An option to hide the browser disables animations and speeds testing by one to two times while separate updates improve annotation transmission speed and token efficiency.

Original post

Codex can now use the in-app browser to test your app at different viewport sizes! It will control the device tool bar and click through your app at different breakpoints to validate & iterate. If it's a long run, Codex will take screenshots at key moments during testing and show them to you at the end of the turn, so you can verify its work. To speed up testing, Codex can hide the IAB to disable animations, and accelerate testing by 1-2x. Separately, we also made annotations send faster and consume less tokens. Hope you enjoy the updates and let us know what you think!

7:43 PM · May 12, 2026 View on X
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In app browser improvements in Codex app. Different viewports, screenshots viewing, better annotations and more token efficient. Happy quality of life improvements Tuesday.

James Sun@JamesZmSun

Codex can now use the in-app browser to test your app at different viewport sizes! It will control the device tool bar and click through your app at different breakpoints to validate & iterate. If it's a long run, Codex will take screenshots at key moments during testing and show them to you at the end of the turn, so you can verify its work. To speed up testing, Codex can hide the IAB to disable animations, and accelerate testing by 1-2x. Separately, we also made annotations send faster and consume less tokens. Hope you enjoy the updates and let us know what you think!

2:43 AM · May 13, 2026 · 191.8K Views
3:07 AM · May 13, 2026 · 57.9K Views