Synthetic user testing for developers

Find failed experiences before users do.

A synthetic user is an AI that uses your product like a real person — it opens your site in a real browser, works through your flows, and reports back where it got confused, lost trust, or gave up.

Run them across your onboarding, signup, and checkout before real customers hit them — and find out what converts without waiting for scale.

Try it on your product
app.acme.com/checkoutRunning
Budget-conscious shopperclaude-opus-4-7
Opened checkout
Chose annual plan
Applied SAVE15
Reviewed order summary
Looked for place-order
Did not complete
Abandoned at the order summary · 3 findings
View
Why it matters

SyntheticUsers discovers WHY users leave

The gap

You can't tell if it works until it's too late

We can build software faster than ever — but the feedback loop on whether it actually works for a person hasn't caught up.

How do you know the homepage you just shipped converts? You can't A/B test it until you have thousands of users hitting it. User research is slow. Analytics shows where people dropped off, not why. So you ship, and you wait, and you find out a flow is broken after someone's already gone.

Synthetic users tell you whether people can get through your product — and whether it converts — before you have the traffic to find out the hard way.

Before scale

Catch usability failures before meaningful traffic exists.

Between research cycles

Quick checks while real user research stays precious.

Every product change

Rerun critical flows when onboarding, pricing, agents, checkout, or activation changes.

How it works

Paste a product link

Works with preview links, prototypes, staging apps, and live products.

01
Paste a product link

Preview links, prototypes, staging apps, and live products.

02
Choose a user and goal

Pick a persona and the journey they're trying to complete.

03
Synthetic users attempt the journey

They open a real browser and work through the flow like a person.

04
Get the failure report

Where they got confused, lost trust, or gave up — with evidence.

05
Fix, rerun, compare

Ship the fix, run it again, and watch the verdict change.

What it catches

The moments a flow quietly loses someone

Synthetic users surface the human failure modes analytics can't name — each reported in the persona's own words.

Confusion

"I don't know what to do next."

Mistrust

"I'm not sure this actually happened."

Abandonment

"This feels like too much work."

Goal failure

"I tried, but never got what I came for."

Expectation mismatch

"The product used different words than I expected."

False success

"The system worked, but I didn't know it."

The artifact

A usability report developers can act on

Not a score — a verdict, the failure moment, the evidence in the persona's own words, and the fix. Switch personas to see the same flow through different eyes.

3 of 5 would convert
app.acme.com/checkout
Rerun all soon
Goal
Apply a discount code and complete checkout on mobile.
Result
Did not complete
Failure moment
Step 5 · order summary — abandoned at payment.
"I keep scrolling… is the button the underlined text? I'll just give up and check on desktop later."
Suggested fix

Promote “Place order” to a filled primary button above the fold; echo the applied discount and selected plan on the summary line.

checkout · order summary · 390px
Discount not echoedPlan not confirmedCTA reads as link
Run
run_8f3a2c
Model
claude-opus-4-7
Duration
2m 14s
Cost
$0.42
Findings3 total

At 390px the place-order control is an underlined text link below the fold, subordinate to “Edit cart”. The persona scrolled past it twice.

82% confidence
Built for the way you ship now

Your agents can build the product. We tell you if it works.

AI is writing more of your product than ever, and the team shipping it is smaller and more technical. Product managers are becoming engineers; engineers ship the whole experience. The skill that's missing isn't more code — it's knowing whether what you just shipped actually works for a person.

Set goals for your app and test against them on every change — so you ship with evidence instead of hope.

deploysimulatereportfixrerun
Run it when the flow matters
  • before launching onboarding
  • before changing pricing or checkout
  • after adding an AI agent or automation
  • before a design-partner demo
  • when analytics shows drop-off but not why
  • as a weekly release check for critical flows.
Why not just evals?

Green evals, confused users

Evals test whether a model gave the right answer. Synthetic users test whether someone can complete the product journey. Your evals can pass while users still get confused, lose trust, or abandon the task.

Your evals can be green while your product is quietly burning its first relationships.

I built an AI-first chat app and gave it to a real customer to test. It passed evals — but the behavior wasn't what I expected, and it burned that first relationship. That's exactly what I should have caught with simulated users first.

— Synthetic Users, founder
ToolWhat it tests
EvalsOutput correctness
Synthetic usersJourney success
QABugs
AnalyticsDrop-off
User researchHuman truth
Where it's going

Is this actually working for the person on the other end?

It's the same question at every level of what you build. Today that's your website and product. Next it's your AI experiences. Further out it's your multi-agent systems — and you can't A/B-test your way to those answers without scale you don't have yet.

We're building toward that as a full developer platform for product behavior:

Coming soon
GitHub

Run synthetic users on every push, deploy, and preview.

Coming soon
MCP server

Let your own agents run the tests and iterate on copy, design, and layout.

Coming soon
Application graphs

Map every path through your product and test each.

Coming soon
Connectors

Email today; Slack, GitHub, and chat next, so agents full-cycle simulate real usage.

Coming soon
Slack companion

An always-on synthetic user you can talk to.

Coming soon
API

Build synthetic users into your own CI and test suites.

Find the failed experience before launch.