WarsawJS Meetup #138 - onsite

# WarsawJS Meetup #138 - You’re invited!

Date: 12th May 2026

Time: 18:30–21:30

Location: Biuro Sienna Center

Sienna 75, 00-833 Warszawa, B1, floor 8.

What to expect?

Faris Aziz - The Hidden Battleground, Engineering High-Conversion Payment Experiences

For most products, the checkout is the most critical and fragile part of the funnel. It’s where traffic turns into revenue, where small UX regressions compound into large financial losses, and where system failures become immediately visible on the balance sheet.

This talk explores how to build resilient, high-converting payment experiences as systems, not screens. Drawing on hundreds of A/B experiments run on tens of millions of users and lessons from operating a global subscription platform generating tens of millions in annual recurring revenue, we’ll look at how payment orchestration evolves as products scale across regions, currencies, and providers.

We’ll cover how to design checkout UX that converts consistently even for low-frequency products, how to orchestrate multiple gateways without leaking complexity to the user, and how to test and monitor flows where failure tolerance is extremely low. Along the way, I’ll even show a shocking example where adding just two form inputs, implemented correctly, could cost over a million dollars in lost revenue.

This is a practical talk from the trenches about why checkout is a hidden battleground, and how resilient payment engineering protects both conversion and growth.

Gideon Awolesi - Classifying Intelligence: Mental Models for Designing AI Products

This talk introduces a structured classification framework for designing artificial intelligence products, breaking AI complexity into tangible diemnsions to give product teams a shared language for building, evaluating, and scaling AI assistants. Drawing from years of designing generative AI experiences, Gideon Awolesi walks through the mental models that bridge user expectations with AI behavior, and presents a formula-driven approach to quantifying assistant power from simple FAQ bots all the way to the frontier of artificial general intelligence.

Rafał Pocztarski - The End of TSC and the Rise of TSGO with TypeScript 7.0 Beta

The beta version of the new TypeScript compiler totally rewritten in Go has just been released. This talk will explain what it means for us in theory and in practice.

Jakub Grzywaczewski - Designing Copilot Architecture: Structuring AI Workflows with .github

How do you turn GitHub Copilot into a predictable part of your engineering system? This talk presents an architectural approach to Copilot using .github as a configuration and orchestration layer. We’ll cover instructions, prompts, and skill - and how to combine them into reusable, team-wide AI workflows.

Our Host: Biuro Sienna Center

Sponsors: Xfaang | Nord Security | Stripe | On The Spot Development

Media partner: K MAG

Partner: JetBrains, Webellian, shroom

By attending the event, you agree to the event regulations.