Join us in 2025!
JSHeroes is a non-profit community-organized event, held every year in Cluj,
Romania. Our goal is to bring together JS and Web/Frontend enthusiasts from
all over the world for a single-track two-day conference with: quality
content, amazing networking and tons of fun. You bring your ideas and desire
to learn, we provide the relaxed atmosphere and the good vibes.
Our 7th edition will take place on the 29th and 30th of May 2025 !
Tickets are available on our ti.to page.
Meet our first 2025 speakers Architecture Chelsea Troy ML Ops Engineer Mozilla
Chelsea Troy ML Ops Engineer @ Mozilla
Chelsea is a Machine Learning Operations Engineer at Mozilla, focused on the role of data privacy and scientific rigor in automation. She teaches Python to formerly incarcerated technologists through Columbia University’s Justice Through Code Initiative, and she also teaches at the University of Chicago Master’s Program in Computer Science. She hosts workshops for professional engineers through O’Reilly as well as her personal site, and writes at chelseatroy.com.
Talk: Designing APIs for Complex Libraries When you build a library that is POWERFUL - can handle use cases in lots of different circumstances - you face a challenge with making that library’s API DISCOVERABLE. Git is a fantastic example of this: it’s a powerful version control library that can solve a LOT of problems for programmers, except that most programmers don’t know 80% of what it does. This isn’t a deficiency in programmers: the library just has a high power to discoverability ratio. For your library to REACH all the use cases it can solve for, your team has to have a discoverability strategy. Join Chelsea to learn about success metrics and implementation options for such a strategy.
Accessibility Hidde de Vries Front-end and a11y specialist
Hidde de Vries Front-end and a11y specialist
Hidde (@hdv) is a freelance front-end and accessibility specialist, currently working in the NL Design System team at the Dutch government. He is also involved in the W3C’s Open UI Community Group and Accessibility Guidelines Working Group. His favourite programming language is CSS and he strongly believes in a web that puts people first. Hidde writes about these things and more on hidde.blog. In his free time, he works on a coffee table book covering the video conferencing applications of our decade.
Talk: Web platform features with a11y built in?
React Ivan Akulov Senior Performance Engineer Framer
Ivan Akulov Senior Performance Engineer @ Framer
Ivan is a Google Developer Expert and a React / web performance engineer. He has previously helped companies like Google, Appsmith, Toggl, and many more – and currently works as a Senior Performance Engineer at Framer.
Outside of work, Ivan enjoys playing dungeons and dragons, discovering lesser-known techno artists, and obsessing over serif typefaces.
Talk: Invisible Hand of React Performance From React.createClass to PureComponent to hooks – React has changed a lot. Each of these changes was driven by a desire for better architecture. But under the hood, each of these changes also pushed us to write faster apps – often, without us even noticing that.
In this talk, let’s look at how React’s invisible hand has been making our apps faster over the past 10 years:
useEffect, and how it’s faster than componentDidMountBatching, and how it improved from version 0.4 to 0.12 to 18
<Suspense>, and some of the less obvious effects of using itand possibly more
TypeScript Josh Goldberg Open Source Maintainer
Josh Goldberg Open Source Maintainer
Hi, I’m Josh! I’m an independent full time open source developer. I work on projects in the TypeScript ecosystem, most notably typescript-eslint: the tooling that enables ESLint and Prettier to run on TypeScript code. I’m also the author of Learning TypeScript (O’Reilly), a Microsoft MVP for developer technologies, and an active conference speaker. My personal projects range from static analysis to meta-languages to recreating retro games in the browser. Also cats.
Talk: Tooling Like It's 2025 TypeScript! ESLint! Biome! Oh my! So many tools exist that we can choose from as modern developers. Do you ever feel like you’re getting lost in a sea of GitHub README.mds and configuration file messes?
Let’s talk about the state of tooling for TypeScript developers in 2025. What are the tools that many developers are finding helpful? How are those tools changing over time to be more helpful (and less annoying to configure)? Why do we even care about tooling when we have TypeScript!?
All those questions and more will be answered. We’ll cover:
The state of common tooling: linters, TypeScript, their integrations together (hello, Rust!)
Some of the great benefits of aggressive static analysis (hello, plugins!)
Miscellaneous other tools such as Knip and TypeChat (hello, AI!)
High-level trends for tooling
After this talk, you’ll be prepared not just to configure your linter and type checker, but you’ll understand why so many developers are excited for that task in the first place.
Design Patterns Lydia Hallie Software Engineer & JavaScript Educator
Lydia Hallie Software Engineer & JavaScript Educator
Lydia Hallie is a software engineer and technical content creator with a focus on React, JavaScript, and web performance. She enjoys sharing technical deep-dives, and strives to make complex concepts accessible to developers of all skill levels.
CSS Miriam Suzanne Oddbird
Miriam Suzanne Oddbird
Miriam is an author, artist, developer, and open web advocate. She’s an Invited Expert with the W3C CSS Working Group, and member of the Sass core team, and a co-founder of OddBird – providing a range of web development and design services, along with in-depth workshops and trainings. Miriam co-authored the specifications for CSS container queries, cascade layers, and scope. Offline, she spends her time making pottery, repairing mechanical clocks, knitting socks, or creating art with Teacup Gorilla & Grapefruit Lab .
Technical Migrations Sophie Koonin Web Engineering Lead Monzo Bank
Sophie Koonin Web Engineering Lead @ Monzo Bank
Sophie is the web engineering lead at Monzo Bank in the UK, responsible for the web platform across the organisation and working on internal tooling that powers Monzo’s award-winning customer service.
Building websites since the age of 10, she’s passionate about creating inclusive, accessible and fun websites that people love. Sophie writes about tech & mental health at localghost.dev, builds intentionally useless web apps, and makes music.
Talk: So you’ve decided to do a technical migration It seems like there’s always a hot new library or framework promising great things. But people often forget about the pain and effort required to move from an old technology to a new one. How long will it take? If you finish, will it be worth it? And if you don’t, could it leave you in a worse place than where you started?
Drawing from my experience of the Typescript migration we recently completed at Monzo I’ll take you through some of the different outcomes of technical migrations and the things we learned along the way.
And our awesome ambassadors
An amazing group of people that ensure top-notch content at the event every
year
Andrei Pfeiffer Ambassador
Andrei Pfeiffer Ambassador
Carmen Popoviciu Ambassador
Carmen Popoviciu Ambassador
Carmen is an emoji hyper-user disguised as a web developer in real life. She enjoys building things on the web and does exactly that on the Pages team at Cloudflare. If you are ever stranded on a remote island and have only three attempts to recover your master password, the secret key code is “dance”.
Ioana Chiorean Ambassador
Ioana Chiorean Ambassador
Ioana is an engineer manager flavored in communities, and devrel, that has more than 12 years of experience in tech with a specialization in mobile apps and web. Besides her daily job, she dedicates her time to building tech communities and improving the access to education. She is the Module Owner for Mozilla Reps, one of the alumna of MozTechSpeakers, and stands as an ambassador for CodeWeek at the European Commission.
In her free time, she contributes to Open Source, tech or sports events, and different volunteering programs. all these while enjoying a coffee or a good wine.
Jeremias Menichelli Ambassador
Jeremias Menichelli Ambassador
He developed interest in the web back when a dial-up modem was the fastest thing on the planet. Now, he has more than a decade of experience building web products of all kinds and lately working in design systems, performance, education and community.
Tejas Kumar Ambassador
Tejas Kumar Ambassador
Tejas Kumar is an international keynote speaker with an engineering background spanning 22 years, from design to frontend to backend to devops. Today, Tejas shares talks at large with developer communities worldwide, equipping them to do their best work.
Bridging the gap
Our ecosystem has an abundance of technologies, tools, frameworks and services to deliver applications faster than ever before. With new standards and ways of building across multiple platforms, developers have wide toolkit at their disposal. But there’s a growing gap between our projects, with accumulated technical debt and complexity, and the tools and frameworks developed by the community. In 2025, we’re bridging that gap.
Our speakers will present solutions for common industry problems, highlight the strugles with managing complexity, maintainability and scalability and will explore new technologies, frameworks and standards that tackle all these concerns.
At JSHeroes, we always ventured outside the pure language ecosystem, so expect to see a variety of talks covering the entire landscape of web development and JavaScript as a universal programming language.
But of course, we will not neglect the human side of things, in our effort to paint a full picture for the development community in 2025.
We believe that the community and the open-source models are well suited for our core values: learning, teaching and knowledge sharing. Our mission is to inspire other communities with the concept of open-source events.
We’re publishing all data about this conference, in full transparency . We are also available at any time for inquires and we’re really looking forward to sharing our knowledge about organizing international events. This way, whenever a community wants to start something similar, they can build on our knowledge.
Venue and facilities
We are hosting the JSHeroes 2024 conference at the Grand Hotel Italia , Vasile Conta Street number 2, Cluj-Napoca, Romania.
See directions on Google Maps .
