CoTester is an AI-powered testing agent that learns product context and converts requirements or user stories into executable test logic. It uses vision-language models to interpret UI screens, an auto-heal engine to adapt to UI changes during execution, and integrates with test infrastructure to run tests on real browsers and devices. CoTester provides debug logs, screenshots, scheduled runs, and guardrails for human approval, enabling teams to speed up test creation, reduce flaky tests, and maintain full ownership of test code and data.