Test what you build with Claude Cowork

According to the Claude help center, Claude Cowork brings the agentic architecture of Claude Code to non-coding knowledge work, with no terminal needed: you describe an outcome and it runs a multi-step task. If you used Cowork to help build a page or a small app and published it at a public address, this guide shows how to have Claude check it from the outside before visitors do. You will get a test plan and a way to let Claude run Avalyz tests itself.

What Claude Cowork is, as documented

The Claude help center says Cowork is available on paid plans (Pro, Max, Team and Enterprise), with availability varying by surface. On the desktop app, Claude reads and writes only in folders you connect, and it can open Chrome to click, type, navigate and fill forms. Cowork supports connectors and MCP, and you choose which connectors Claude may use; plugins that include local MCP servers work only in the desktop app. Check the current help page for the exact plans and surfaces, because they change.

What can go wrong with a page or app you published

The published address differs from the preview: broken links, missing files, wrong paths.
A contact or sign-up form looks fine but does not reach you.
The page is unreadable on a phone.
Text is hard to read, or images have no text alternative.
A page loads slowly or shows an error on a direct visit.
Cookies and tracking appear with no notice.

Open the published address in a private window, not the preview.
Check the page on a phone and on a laptop.
Click every link and button once.
Reload a deep page and visit an address that does not exist.
Try each form with an empty and an unusual value, then confirm where the message arrives.
Read all text for typos and leftover placeholder content.
Check that images show and have text alternatives.
Use the keyboard alone to move through the page.
If there is a sign-in, create a test account and try a wrong password.
Look for visible debug messages, test data or private information.
Read the cookie and privacy notices as a visitor.
Run an independent read-only test on the public address.
Paste the report back into Claude and ask for fixes.
Publish again and re-run the same test to compare.

Let Claude run the tests through MCP

Avalyz provides an MCP server file for Claude Desktop and Cowork. Setup, as given on the integrations page:

Download the file once with curl -O https://avalyz.com/av/integrations/avalyz_mcp.py.
Add a server named avalyz to the MCP configuration of the app: command python3, argument the path to avalyz_mcp.py, and an environment variable AVALYZ_API_KEY holding your key.
Restart the app.

Claude can then start tests and read the reports itself. Keep the key out of any shared file. We have not verified here which screen of Cowork exposes this configuration, so follow the current Claude help center for adding a local MCP server in the desktop app.

If you prefer not to set anything up, you need no key at all: open https://avalyz.com/essai?url=YOUR_APP_URL or use the free test, then paste the report into your Cowork session.

What an independent test adds

The assistant that wrote your code knows your intentions, so it tends to check what it meant to build. A separate tool that sees only the published address behaves like a visitor: it does not read your code and does not share the assistant's blind spots. Avalyz proves what it saw; it does not vouch for the rest, and a clean report is not proof that the app has no defects. It is a second pair of eyes, not a substitute for your own judgement.

Test your Claude Cowork app with Avalyz

Avalyz tests a web application from the outside, in real browsers, and returns a verdict with evidence. Start free at /banc: paste your app's address, no sign-up, 3 tests a day. Or open https://avalyz.com/essai?url=YOUR_APP_URL with your own address in place of YOUR_APP_URL: it fills in the address and starts the test.

Read-only by default. By default, nothing is created or changed on your app. Only public addresses are accepted.
Optional test account. If your app has a login, give a test account: the sign-in form is then the sole form submitted, and the signed-in pages are explored read-only.
A GO / NO-GO verdict with evidence, findings ranked by severity, and a report you can paste back into Claude Cowork so the fix goes to the tool that built the app.
Plans, in US dollars with no commitment, are on /tarifs; there is also a 14-day trial of the Pro plan with no card.

FAQ

What is Claude Cowork?

Per the Claude help center, it applies the agentic approach of Claude Code to knowledge work, with no terminal required, on paid plans.

Can Cowork test my published page by itself?

It can open a browser on the desktop app, and with the Avalyz MCP server it can also run independent tests and read the reports. Avalyz only accepts public addresses.

Do I need to be technical?

The free test needs only the address. The MCP route needs one file download and one configuration block.

Will the test change my page?

By default no: it is read-only, and the sole form submitted is the sign-in form, with the test account you provide.

What if my page is not public yet?

Publish it at a public address first. Avalyz cannot test a private or local address.

Related guides: Test an app built with Claude Code, Test a vibe-coded app, Test a Lovable app. Overview of every tool: AI app builders.