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Momentic covers repair, triage and operation
AI made authoring cheap, and authoring was never the cost. The recurring work is repair, triage and operation.
comparison
/ momentic-vs-build-your-own
Momentic vs building it yourself
Momentic provides the testing platform around your tests. Building it yourself means owning repair, triage, operation and the device fleet.
Web, iOS and Android · CLI · CI · MCP
In-house cost model
One developer keeps about 25 tests at 80% coverage.
The share of your critical flows with a test.
A test that fails all day counts as one investigation. Google reports 1.5% of test executions with a flaky result
Salary, benefits, hardware and overhead, over 2,080 hours. Benefits add a third to the wage. BLS puts the mean San Jose developer wage at $106.59 an hour
Steps, runs and hours
A click, an input, or a check is one step. A checkout test runs longer than a benchmark task. Online-Mind2Web tasks average 8.9 steps
The year holds 260 working days. Raise it if you run the suite on each deployment. A work year holds 260 to 262 workdays
Outline the flow, write the steps, make the data, and confirm it passes. TTC Global measured 84 minutes for one test by hand
Repeat the failure, find the cause, fix the test, and get it reviewed. Lower it if you triage a batch of tests together. Undo research puts a full find and fix at 13 hours
To build and keep the suite in house$886,893each year
Investigating failures is 62% of the cost.
- Investigating failures
- $548,438 · 61.8%
- Writing the tests
- $187,500 · 21.1%
- Model inference
- $142,963 · 16.1%
- Runners and CI
- $7,992 · 0.9%
Assumptions
- A working year is 260 days, or 2,080 hours.
- A standard runner has 2 cores at $0.006 each minute, and Playwright advises one worker for each core. At 60 seconds a step, a 15 step test bills 7.4 runner minutes. Checkout, dependencies and storage are extra.
- One step costs 5.9 cents. The most accurate model in the Stagehand agent evals of 10 July 2026 bills 52 cents a task, and a task averages 8.9 steps.
- That model completes 90.6 of every 100 tasks, so the repair work above stays.
The Stagehand agent evals bill each task at frontier lab API rates.
At a glance.
How Momentic and In-house compare across the dimensions teams evaluate most.
| Category | Momentic | In-house |
|---|---|---|
| Authoring | Plain-English steps as YAML in your repo, written by Cursor, Claude Code or Codex over our MCP server | Your engineers write the tests and the framework around them |
| A UI change | The run re-resolves the locator and writes the repair back; the heal agent opens a pull request for the permanent fix | Someone edits the selector, once per test, once per change |
| Cost per step | A cached step replays with no model call | You build the replay-or-re-resolve logic and pay per action when it re-resolves |
| A failed run | momentic ai classify sorts it into bug, application change, test issue or infrastructure | Someone reads the run and decides |
| Flaky test | Quarantine is built in: the test runs, the result reports, the exit code is unaffected | Your own skip list |
| Mobile | Hosted Android 15 emulators and iOS 26 simulators, provisioned in under a second; local AVDs and simulators supported | You run the device fleet or buy a device cloud |
| Coverage | The app graph builds a coverage model from run traces | A list of test names |
| Operation | Runner, sharding, retries, reporters, browser and driver upgrades are ours | A standing engineering job |
| Track record | Notion, Retool, Webflow, Xero and Quora run on Momentic | Your team owns the result |
| Best fit | A suite that changes often and needs ongoing maintenance | A small, stable suite you can maintain by hand |
What building it yourself means
Writing a first E2E test is cheap. The expensive part is the testing platform you build and run around those tests to keep them reliable as the product changes. It becomes a system your team maintains for the life of the product.
With current models, you can build it. The question is whether your team wants to build, run and maintain an internal testing product instead of shipping its own. A test can pass once and still require ongoing maintenance to gate releases reliably. That maintenance accounts for most of the cost.
Where Momentic differs.
02
Momentic replays cached steps
Momentic replays a cached step with no model call, and over 99% of steps finish in under 500ms, so a steady-state run costs about what plain Playwright costs. Cloud runs still bill one credit per step.
03
Momentic sends repairs as pull requests
Momentic sends the permanent repair as a pull request. The post-run heal agent rewrites the failing test, so a fix arrives as a code review.
04
Momentic classifies failed runs
Momentic classifies a failed run into four categories with its reasoning, so a failed build is worth acting on instead of guessing whether it is noise.
05
Momentic includes mobile infrastructure
Momentic includes mobile with hosted Android 15 emulators and iOS 26 simulators, so you do not need a fleet of your own.
06
Momentic operates the testing platform
Momentic operates the parts you would otherwise staff: runner, sharding, retries, reporters, browser and driver upgrades, plus the knowledge base that learns your product terminology.
07
Mo finds the bugs no test covers yet
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. An exploratory agent with a reproducer gate is a second platform to build and run; Mo comes with the first.
Eleven ways to test a browser.
Building it yourself is one way to test a product. Read the authoring column first. Who can add a test decides what the suite costs you to keep.
| 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 |
| In-house | Your engineers write the tests and the framework around them | Browsers, simulators and emulators you run or buy | Teams that want to own the testing platform |
| 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 |
| Selenium | Code in Java, Python, C#, Ruby or JavaScript | Every major browser through WebDriver; Grid or a vendor cloud | Large suites that need one API across several languages and browsers |
| 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 |
| 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 |
| 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 |
Who should choose which.
Choose Momentic
Choose Momentic if the suite has to survive weekly UI churn, and you would rather review a repair than write one. Quora cut a 7-hour QA pass to 30 minutes, so the suite now runs on every merge instead of once a release.
Choose In-house
Choose in-house if you have a small stable suite you can maintain by hand, or a hard constraint that rules out a SaaS dependency.
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.”
Momoko F. Head of Product Operations, Quora
30 min
daily test execution, down from 7 hours
500+
manual test cases replaced
100%
critical tests created in one month
Frequently asked questions.
Can we build this ourselves with Playwright and a model?
Yes, with current models. The cost is repair, triage and operation, and it grows with the app.
How do we size the cost of building it?
Count four things. Engineer-hours each week on repairs and triage. Engineer-hours on the framework itself: the runner, sharding, retries, reporters, and browser and driver upgrades. Model inference on every AI action you do not cache. The infrastructure you run it on: browser runners, emulators and simulators, CI minutes, and storage for videos and traces. Our build vs buy guide sizes the engineer time at one day a week on repairs and half a day on the framework, about 620 hours a year, and those hours are illustrative rather than a measurement of your team.
How do we compare the two fairly?
Run the bake-off from our build vs buy guide: pick a recent redesign and a flow with a history of breaking, cover the same journeys both ways, let both run through a few weeks of real merges, and count the interventions a person had to make.
Do cached steps cost credits?
Yes. Every step executed costs one credit, cached or not, whether the run is in the cloud or from the CLI.
Do we still own the tests?
Yes. The YAML lives in your repo, changes arrive as pull requests, and Momentic runs them in your CI.
Still have additional questions?
Contact us