Momentic stores YAML tests, runs them on a managed runner and heals cached steps in place. Stagehand adds AI primitives to Playwright for teams that want programmatic TypeScript control.
Web, iOS and Android · CLI · CI · MCP
How Momentic and Stagehand compare across the dimensions teams evaluate most.
| Category | Momentic | Stagehand |
|---|---|---|
| Authoring | Cursor, Claude Code or Codex write the YAML into your repo over MCP; the CLI runs it | TypeScript with AI primitives on Playwright |
| Maintenance | Self-healing, intent-based locators | The team maintains the Playwright code and cache behavior |
| Test types | E2E and visual checks | Playwright tests with AI actions and extraction |
| Browser coverage | Chromium, Chrome (Safari/Firefox on roadmap) | Playwright browsers |
| Infrastructure | Hosted browsers, or the CLI on your own CI runners | Your runner or Browserbase |
| Pricing | Free tier; pay-as-you-go and enterprise paid plans | Open source |
| Best fit | Your coding agent adds tests over MCP, with no page objects to maintain | Engineers who want AI steps inside a TypeScript Playwright codebase |
Stagehand is an open-source TypeScript library from Browserbase. It adds four AI primitives, act, observe, extract and agent, on top of Playwright. Browserbase Cache and Browserbase Model Gateway are available with the BROWSERBASE environment. Stagehand fits teams that want programmatic TypeScript control with a thin AI layer over Playwright.
01
A Stagehand act call asks a model what to do on the page, so a rerun can take a different path and each action costs money. Momentic resolves a step once, caches the signals it used, and replays it without a model call. The same commit gets the same verdict.
02
Stagehand adds AI calls to a Playwright codebase. Momentic stores plain-English steps in YAML, so the same artifact is reviewed in Git and run by the CLI.
03
Stagehand's Browserbase Cache keys on the page accessibility tree, so structural changes can flip the key and create a new entry. Momentic re-resolves a miss and updates the cached step in place.
04
Stagehand has no native assert primitive. Teams use Playwright expect or build an assertion from observe and extract. Momentic has assert steps and visual assertion steps in the test format.
05
Stagehand leaves runner, reporter and recovery choices to the team. Momentic includes a CLI, run artifacts, triage, quarantine and a managed dashboard.
06
Momentic classifies a failure inside the run, when retries are exhausted, so the CLI exits with a category, the reasoning and a triage action, and a test failing on infrastructure can be quarantined by rule and posted to Slack. A Stagehand suite reports what your own harness reports.
07
A styled wrapper usually covers the real checkbox or input, so an action aimed at the semantic element hits nothing. Momentic hit-tests inside the element bounds and drives the topmost visible interactive element instead, on every interactive step. A library leaves your team to find and work around each case.
08
Momentic resolves each step against a screenshot, the accessibility tree, and the DOM on web or the screen XML on mobile, and infers from the step description which signal matters. 'The Sign in button' resolves from accessibility attributes and text. 'The red Cancel button below the order summary' resolves from position and pixels. An element the screenshot does not show, or two that look alike, still resolves, and AI assertions read the same three sources.
09
Mo takes a target and a brief, plans the test cases, and runs each one in its own hosted browser, simulator or emulator, a hundred or more at once. A suspected bug goes to a reproducer agent that starts from a clean session, and only a reproduced bug reaches the report, with a recording and repro steps. One session ran 116 agents and returned 27 bugs. A Momentic test covers a flow on every merge; Mo covers the flows nobody has written a test for.
Agentic browser tools split between live interaction and saved tests. Read the authoring column first, because what a tool leaves behind is what your team maintains after the first run.
| Tool | Authoring | Runs on | Best fit |
|---|---|---|---|
| Momentic | Plain-English steps as YAML in your repo. Cursor, Claude Code and Codex write them over our MCP server, and the CLI runs them | Web, iOS and Android; cloud browsers, simulators and emulators | The suite lives in the repo and gates CI, with no framework to maintain |
| Playwright MCP | The agent drives a browser over MCP and can emit Playwright code | Chrome, Firefox, WebKit or Edge; the agent's machine | Letting an agent work on a page. The emitted code needs a Playwright runner and a review before CI uses it |
| Stagehand | Code plus natural-language actions, on Playwright | Playwright browsers | Engineers who want AI steps inside a Playwright codebase |
| Browser Use | Prompts to an agent, in Python | Chromium | Agentic browsing research rather than regression |
| Playwright | Code: TypeScript, Python, Java or C# | Chromium, Firefox and WebKit; your runners | Engineers who want full control and accept selector upkeep |
| Cypress | Code: JavaScript and TypeScript | Chromium browsers, Firefox and WebKit; your runners or Cypress Cloud | Front-end teams who live in the in-browser debug loop |
| Puppeteer | Code: JavaScript and TypeScript | Chromium and Firefox; no test runner of its own | Scripting and scraping, not a regression suite |
| WebdriverIO | Code: JavaScript and TypeScript | Browsers through WebDriver or CDP, plus mobile through Appium | One runner for both web and native apps |
| mabl | Low-code recorder aimed at non-technical authors, with JavaScript for the hard parts | Web and mobile web; vendor cloud | QA teams who record in a vendor app instead of writing code |
| BrowserStack | Bring your own Playwright, Selenium or Cypress tests | Real browsers and real devices; vendor cloud | Buying browser and device coverage, not authoring |
Choose Momentic
Choose Momentic if the same commit must give the same verdict: a cached step replays with no model call, assertions are in the format, and the runner, the reports and the triage come with it.
Choose Stagehand
Choose Stagehand if you want AI calls inside TypeScript you control, in a Playwright codebase you already own.
Trusted by teams who made the switch.
“Momentic gave us a fast and reliable way to validate Poe.com's AI responses, even when they weren't deterministic.”
30 min
daily test execution, down from 7 hours
500+
manual test cases replaced
100%
critical tests created in one month
That depends on how much of the run is an AI action. An AI action adapts to a changed page, and it is also non-deterministic, slower and priced per action. Momentic replays a cached step without a model call and calls a model only when the cache misses, so the same run gives the same verdict.
Yes. Stagehand is an open-source TypeScript library from Browserbase. Momentic offers a free tier, with paid plans for larger usage.
Stagehand provides act, observe, extract and agent on top of Playwright. It does not provide a native assert primitive.
Browserbase Cache stores a resolved action for an act call and keys it on the page accessibility tree. A structural change can create a new entry. Local Cache stores JSON in the repository.
Yes, if you want YAML tests, a managed runner and built-in assertions. Teams that want direct TypeScript control inside Playwright may prefer Stagehand.
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