1.7ReAct in Production Tools (as of July 2026)

You rarely implement the raw loop yourself anymore. Production SDKs and frameworks package it, and you should be able to name them:

Tool	What it is	The ReAct connection
Stagehand (Browserbase)	The standout agentic browser SDK (~22.8k GitHub stars)	Its TypeScript intent API -- act("click the submit button") -- is the Think+Act phases exposed as a single call; the SDK observes the page and resolves the intent to a concrete action
browser-use	The most popular open-source AI-browser-agent framework (~81k stars)	A full Observe-Think-Act-Evaluate loop over the browser, driven by an objective prompt
Playwright Test Agents	Planner, generator, and healer agents shipped with Playwright since v1.56 (npx playwright init-agents)	The healer is a ReAct loop triggered on failure: observe the broken state, reason about the change, act to repair the test

Adjacent to these -- and worth knowing for interviews -- are autonomous software-engineering agents like Devin (Cognition). Devin is an AI-SWE agent, not a test framework, but it runs the same loop against codebases instead of browsers, and its Devin Review feature performs autonomous first-pass code review that catches logic errors and missing edge cases before a human looks at the PR. Where a QA architect meets Devin is in reviewing and gating its output, not in replacing test infrastructure with it.