Inside Pneuma's data system, built from zero with Convex Works

Pneuma is a mental-health marketplace: a short questionnaire, a matched psychologist, and two introductory sessions to see if the fit is right.

Convex Works built its measurement from the beginning, before the company had real traffic, and kept building it release by release as Pneuma grew.

This is what that setup actually looked like, from the first tracking plan to the surprises that showed up once real data started to flow.

At a glance

• Built from zero, before the product had real traffic (2023)
• More than 1,500 visitors a week tracked by 2025
• Conversions tracked on Pneuma’s own tag manager, independent of the agency-run ad account
• Funnel counting errors found and removed before they drove decisions

Built from zero, release by release

Pneuma started with nothing to measure. Convex Works came in at the beginning, in 2023, while the product was still taking shape, and built the measurement as the company launched and grew.

The work ran release by release, in step with Pneuma’s own engineer, through the product’s launch in October 2024 and a full rebrand in early 2025.

This was not a system handed over once. It was built, corrected, and extended as Pneuma grew from a handful of first customers into a real marketplace.

The tracking that had to be right from the start

Before the site had real traffic, we set the measurement plan: every step of the marketplace, from sign-up through choosing a therapist, choosing a session, and paying.

The events that decide the business, i.e. sign-up, checkout, and purchase, are captured on the server, where an ad blocker or a browser can’t drop them.

The website side runs on Piwik Pro: EU-hosted, with web analytics, the tag manager, and GDPR consent in the one tool. For a mental-health marketplace in Europe, that means the site collects data only when the visitor has allowed it.

The surprise once the real numbers arrived

In late 2024, once the funnel was live, it showed something impossible: more people finishing onboarding than reaching the step before it.

We traced it, with Pneuma’s engineer, to a redirect that was firing a “completed” event for people who had already finished and landed back on the home page. It was removed.

Returning customers loading the home page were inflating the count too, so the success signal was moved to the step after payment, where it only counts people who have actually paid.

None of this was visible in the raw reports, which looked fine. It only showed up because the funnel was being read closely, step by step.

Deciding what counts as a conversion

Which step counts as the conversion is a decision, not a detail. For Pneuma we fixed it at the post-payment step, the honest one, and kept the checkout on a stable /onboarding/ path so the number stayed measurable even as the site was rebuilt around it.

Those conversions feed Google Ads through Pneuma’s own tag manager, not the third-party agency’s account, so the setup belongs to Pneuma whoever runs the campaigns.

The Meta pixel is in place for when paid social starts, though it wasn’t running ads during this work.

Owning the pieces that matter

As Pneuma grew, we moved its heavy assets, the onboarding and story videos, onto storage it owns rather than embeds that expire and break.

Consent and hosting run on EU infrastructure Pneuma controls, not locked inside a vendor.

Where it left Pneuma

By 2025 the measurement covered a real marketplace, a site drawing more than 1,500 visitors a week.

When Pneuma rebuilt its homepage, and later its onboarding, it could see the effect in numbers it trusted: time on the page up and bounce down, on a funnel it could finally read from first visit to payment.

The counting errors that would have inflated those numbers had already been found and removed.

The system did not stay still either; it grew with the company, release by release, and Convex Works is still the team Pneuma asks when a number needs explaining.

The stack

The measurement runs on a small stack Pneuma owns. What we built:

Collection
Webflow	The marketing site, rebuilt release by release.
Piwik PRO	EU-hosted web analytics and the tag manager. The events that decide the business are captured server-side.
Compliance
Piwik PRO	GDPR consent in the same tool, so the site collects only what the visitor allows.
Ownership
Cloudflare R2	Onboarding and story videos self-hosted on Pneuma's own domain, not expiring embeds.
Distribution and activation
Mixpanel	Product analytics: every marketplace step, from sign-up to purchase.
Google Ads	Conversions fed through Pneuma's own tag manager, independent of the agency-run account.
Meta Pixel	In place for when paid social starts.

Measurement you can trust from day one

This is the kind of data system we build at Convex Works: the infrastructure behind the ad spend, built by people who have actually spent it. Start with an audit.