First simulation
Free
1 complete user review
Report and session recording included
Make product decisions with user digital twins.
A digital twin of your target user tries your live website or iPhone app. In about 20 minutes, we’ll email you a user report showing where they convert, where they hesitate, and what to change.
Join your team’s workspace
Members can view existing and future reports and run simulations using the workspace’s shared credits.
Sign in to run your simulation
Your link and research plan are saved. Sign in so we know where to email your report.
or use email
Rerun the saved simulation
This uses one simulation from your available allowance.
Your simulation is queued
We’ll begin reviewing your website shortly.
- Website
- Research plan
- Target audience
- Device
Open report →
- Website
- Research plan
How it works
A faster decision loop for
Watch a digital twin of your target user try your product. Modeled on real customer personas, it explores the product, completes tasks, answers questions, and turns the experience into specific, prioritized feedback.
-
01/ 04
Define your target audience
Add your website, choose desktop or mobile, and select or describe a persona that reflects the customers you want to understand.
Website https://yourproduct.comDevicePersona
First-time visitor New to your product- Context
- Followed a link from a friend. Has never heard of the product and will give it about a minute.
- Goal
- Work out what it does and whether it’s worth signing up.
- Cares about
- Clear valueLow effortNo surprises
-
02/ 04
Set tasks and questions
Give each user a goal, like completing site onboarding or selecting a subscription plan, and ask questions about clarity, trust, appeal, or anything else that matters.
Task 1Starting on the homepage, and without signing up, work out what this product does and who it’s for.
- Q1In one sentence, what does this product do?Open answer
- Q2How clearly does the homepage say who it’s for?1–5 scale
Task 2Explore for a few minutes, then decide whether you would sign up.
- Q1Where did your first guess turn out wrong?Open answer
- Q2What would change your mind about signing up?Open answer
Task 1Sign up and try to get your first useful result, as a brand-new user would.
- Q1How many steps did it take before you got something of value?Open answer
- Q2Where were you asked for more than seemed necessary?Open answer
Task 2Use the product for a few more minutes after your first result.
- Q1When, if ever, did it start to feel worth it?Open answer
- Q2How likely would you be to come back tomorrow?1–5 scale
Task 1Work out the main thing this product promises to help with, then do it without outside help.
- Q1Did you finish? If not, where did you give up?Open answer
- Q2How easy did it feel?1–5 scale
Task 2Do the same task a second time, now that you know the product.
- Q1Where did what happened differ from what you expected?Open answer
- Q2Would you choose this over how you do it today?Yes / No
Task 1Decide whether you trust this product enough to give it your email and your data.
- Q1What made it feel credible, or raised doubts?Open answer
- Q2How clear was it what happens to your data?1–5 scale
Task 2Find out who is behind the product and what you’re committing to by signing up.
- Q1Did anything feel vague, missing, or off?Open answer
- Q2What one change would most increase your trust?Open answer
Task 1Find the pricing and choose the plan you would pick. Stop before any payment is taken.
- Q1Was the pricing easy to find and understand?1–5 scale
- Q2Were any limits, trials, or billing terms surprising?Open answer
Task 2Compare the cost with how you’d solve this problem today.
- Q1Is it worth the price to you?Yes / No
- Q2What would make the paid plan an easy yes?Open answer
-
03/ 04
Review the findings
See whether the goal was completed, watch the recorded session, and get clear, reproducible findings with supporting evidence and recommendations.
-
Asking for a card before people try anything turns most new visitors away.
Fix Let people create their first project before asking for payment, and say clearly that the trial needs no card.
-
Marketers, the intended audience, decide the product is for developers.
Fix Lead with the result marketers get, and move the technical details to a page for developers.
-
Trial users can’t see what makes Starter worth paying for.
Fix Include team sharing in Starter, or show what Starter adds over free tools right beside the price.
-
On phones, new users can’t find the button to finish signing up.
Fix Keep Continue visible above the keyboard, or move on automatically once the code is entered.
-
Shoppers in Germany hesitate when every price is in US dollars.
Fix Show prices in euros to visitors in Europe, and offer SEPA Direct Debit at checkout.
-
The new dashboard wins, but customers immediately ask how to export it.
Fix Add a CSV export before launch, or say on the dashboard that it’s coming soon.
-
The setup checklist gets new users to their first result quickly.
Keep doing Keep the checklist as the first screen after sign-up when onboarding is redesigned.
-
-
04/ 04
Iterate swiftly
Apply the feedback and re-simulate in minutes, without waiting for real users to give the right feedback or run into issues on their own.
Builder reactions
What builders said after Constants explored their products, surfaced the rough edges, and gave them something concrete to improve.
“This is incredibly valuable feedback. An outside perspective can really see things differently and more realistically.”
“This is pure gold. Amazing feedback. I’ll fix it.”
“Dang dude! This is quality feedback!”
“I have implemented these changes. I really appreciate it.”
“Your setup for this is pretty cool! Thanks for giving it a run.”
“You gave me a few new angles to look at. I’ll fix all of those in the next couple of days.”
“Thanks, I appreciate it!”
“They’re mostly API issues. We will work on it. I’m so grateful.”
“Thank you. That’s a lot of great feedback.”
“Amazed by how detailed the report is and how it covered most of the issues I have, including those that needed fixing.”
“These are all nice finds, and I’ll fix them today. I appreciate all your efforts.”
“Thank you. I will fix these now :-)”
“Incredibly appreciate the feedback. Thank you.”
“That is a genuine mistake and inconsistency I did not notice. I will fix it.”
“Thanks, will update!”
“Thanks a bunch!”
“Appreciate the signup attempts! I’ll take a look and see what the bug could be.”
“This is exactly the kind of feedback I was looking for. You caught several things I completely missed.”
“That’s some really honest and useful feedback. I’m impressed.”
“Thank you for such detailed and actionable feedback! I honestly didn’t consider accessibility at all, so this is great.”
Get started
Run your first user simulation free.
A single simulated user review can uncover functional issues and useful product feedback. Start free, then work with us to develop a simulation strategy for your critical product decisions.
Simulation strategy
Make product decisions with confidence.
Every decision raises different questions. We’ll help identify what matters, simulate the right users and scenarios, and turn the results into evidence your team can act on.
Book a Call ↗Team
Before Constants, we were product and engineering leads at Waymo. There, simulation modeled real human driving behavior at enormous scale, helping Waymo improve safety beyond human benchmarks and drive hundreds of millions of fully autonomous miles. We built the models and developer tools that made those simulations useful, repeatable, and accessible across the company.
Our mission at Constants
Give entrepreneurs, developers, and product teams the same leverage: simulation of real user behavior that shows teams what customers will do before they ship and helps them build better products faster.
