ReactJS Barcelona

ReactJS Barcelona - April 2026

Wed, Apr 8 · 6:30 PM CEST

Skyscanner office, Plaça Catalunya 1, 5-D, Barcelona, al, ES

April Meetup is here! Let's gooo! We have some amazing speakers, and of course pizza and drinks will be available after the event.
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18:30: Welcome
Grab a drink, and a seat until everybody arrives!

18:45 Intro by Host Neciu Dan

19:00 Type safety across the network chasm
Speaker: Alexander Vechi, Product Engineer at SkyScanner

Type safety often stops at the network boundary. In this talk, Alex will look at how modern frameworks try to bridge that gap, and share lessons from Skyscanner’s setup with protobuf-generated TypeScript types, including versioning, nullability, and validation to make API contracts safer in real frontend code.

19:25 Building a Workflow Builder From The Ground Up
Speaker: Martí Serra Molina Frontend Engineer | Creator of Formity

Workflow builders are powerful tools for visually designing and automating complex processes, but building one from scratch in React poses unique challenges. Most teams reach for React Flow to handle node-based diagram rendering, yet there is still significant logic to build on top of it — a node layout algorithm, workflow state modeling, drag-and-drop, undo and redo, and more. In this talk, you will learn how to build a workflow builder from the ground up and the real-world complexities that emerge along the way.

19:50: Drinks and networking!
Do you want to talk at this meetup? Reach out to Dan Neciu on LinkedIn

And please help us spread the news and grow the community:

20:55 Meetup finished

(FOR EARLY ACCESS: WE ALWAYS POST FIRST ON SOCIAL MEDIA)

Twitter(X)
BlueSky
LinkedIn
Instagram

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Sponsors:

Skyscanner

🌎 We're here to help every traveller explore the world effortlessly, with a vision to become the world's number one travel ally.
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Join the Master Security Course for FREE!

Modules 1 & 2 are live now — Exploits and XSS — completely free to access.

• Understand how common vulnerabilities actually work
• Learn to identify and prevent security flaws in your code
• Get practical, real-world examples you can apply immediately
• Types of XSS + real case studies of XSS in ReactJS and more

This is just the beginning — start building security expertise today.
Join here

ReactJS Barcelona x Preply Meetup

Wed, Apr 29 · 6:30 PM CEST

Preply [5th floor], Carrer de Badajoz 97, Barcelona, ES

Second Meetup in April OMG!!! Let's gooo! We have some amazing speakers, and of course, pizza and drinks will be available after the event.
──────────
18:30: Welcome
Grab a drink and a seat until everybody arrives!

18:50 Intro by Host Neciu Dan

19:00 Front-end testing at Preply: Shifting left towards component testing with Storybook
Speakers: Lukasz Rados and Dominika Szukala, both Senior Frontend Engineers at Preply

Preply invested a lot into E2E testing in the past, but this approach wasn’t scaling well for us. With the advent of the company rebrand and the new engineering excellence culture, Preply needed a new approach to front-end testing. We (Dominika and Lukasz) embarked on a project to apply the new Engineering Excellence principles to front-end testing, providing the tools and fixing the current context to steer the whole company toward component tests.

19:25 AI vs. App Engineer. Claude vs. Stack Overflow,
or How an Animation Task Can Change the Perception of Your Work
Speaker: Arthur Repin, App Engineer at Preply

I had a task, that initially looked like a routine change. Normally, I would handle it the usual way: check the documentation, browse Stack Overflow, try a few naive solutions, iterate, and get it done.

But not this time.
This is a story about how a wrong estimate can actually pay off later by saving time on future tasks. It’s a journey through misjudged effort, shifting approaches, unexpected struggles, and the lessons learned along the way.
It also includes a deep technical dive into React Native animations, exploring complex animation patterns and why achieving smooth performance, especially on Android, is still a challenge.
This talk is for engineers who want a deeper understanding of React Native animations and a reminder of why engineers still matter in the age of AI.

19:50: Drinks and networking!
Do you want to talk at this meetup? Reach out to Dan Neciu on LinkedIn

And please help us spread the news and grow the community:

20:55 Meetup finished

(FOR EARLY ACCESS: WE ALWAYS POST FIRST ON SOCIAL MEDIA)

Twitter(X)
BlueSky
LinkedIn
Instagram

──────────
Sponsors:

Preply

We power people’s progress. At Preply, we’re creating life-changing learning experiences by pairing the magic of human tutors with the power of AI. We help learners discover the perfect tutor, craft a personalized learning journey, and stay motivated to keep growing – wherever they are in the world. With a global network of 100,000+ tutors teaching 90+ languages across 180 countries, Preply is shaping the future of learning. Backed by $150M in Series D funding, we’ve reached unicorn status and are scaling fast – all while staying grounded in our mission to make learning more personal, powerful, and human.
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Join the Master Security Course for FREE!

Modules 1 & 2 are live now — Exploits and XSS — completely free to access.

• Understand how common vulnerabilities actually work
• Learn to identify and prevent security flaws in your code
• Get practical, real-world examples you can apply immediately
• Types of XSS + real case studies of XSS in ReactJS and more

This is just the beginning — start building security expertise today.
Join here