Conference talks by Carsten Windler
Serverless PHP with Bref
International PHP Conference 2026 - Berlin, Germany
Have you ever thought about serverless PHP? Thanks to the open-source bref.sh project, we can run our code on AWS Lambda.
This talk will provide you with the background information you need to decide if serverless PHP is right for you. We will then share insights and lessons learned from our experience of operating a customer-facing API with PHP, bref.sh and AWS API Gateway.
You will learn about performance, cold-start latency, file-system limitations, code organisation, and much more. We will not only cover the positive aspects, but also the challenges we faced during implementation and the decisions we questioned in hindsight.
For example, was it a good idea to not use a PHP framework? Come and find out!
Bridging Product and Engineering for a Greener Future: Embedding Sustainability into Software Teams
UXDX EMEA 2026 - Berlin, Germany
Even sustainability-minded teams face friction when balancing product roadmaps with greener engineering practices. In doing so, they are missing out on a lot of potential to reduce not only emissions but also costs.
This talk explores how to integrate sustainability into everyday development without slowing delivery. You’ll learn practical steps to embed sustainability into existing delivery workflows. We’ll discover how to quantify carbon emissions in software and cloud infrastructure and what low-hanging fruits there are to reduce them.
Finally, we discuss what part Product can play in greening your software product, since it’s not only about engineering. You’ll leave the conference with plenty of ideas and concrete actions for a greener software delivery
Know your content footprint – sustainable publishing in a digital world
Neos Conference 2025 – Karlsruhe, Germany
A Content Management System, like every software out there, has an impact on the environment. The point is: we usually don’t see the fumes and the dirt that it causes behind the polished web frontend or the fancy administration interface. But it’s there, and we all should be aware of it.
In this talk, we’ll discuss why the IT is such a significant contributor to the worldwide carbon emissions. We’ll talk about why the insatiable hunger for more and more computational resources even gets worse, and what every one of us can do against it – starting with your favorite CMS.
Sustainable web development — The what, why and how
c`t webdev 2024 - Cologne, Germany
Although we don’t see any dark fumes coming out of our computers, the use of IT comes at a significant environmental cost. The share of global IT greenhouse gas emissions was already equal to that of the aviation industry — even before the AI hype.
This talk will introduce you to the core concepts of sustainability in web development — what are the main drivers of emissions, how can emissions be measured and, of course, how to reduce them.
And even if you are not primarily interested in sustainability, you may be interested in the positive side effects of Green IT, for example on your provider bill or your website success.
Sustainable Software - it’s a win-win-win situation
Green Software Development Munich Meetup 2024 - Munich, Germany
Are you still unsure whether Green IT is worth implementing in your organization, or do you need some good arguments to convince your colleagues?
Writing sustainable software is not just a win for the planet. Focusing on lean and efficient systems has several other, often less obvious, benefits for all stakeholders.
In this talk, we’ll discover how sustainable software engineering can simultaneously advance environmental goals, improve business profitability, and increase developer satisfaction.
How to write sustainable web applications
PHP Developer Day 2024 - Dresden, Germany
Software that is built with sustainability in mind not only has a lower carbon footprint, but it is usually more performant, cheaper to operate and robust. Quite some benefits you won’t miss for sure.
But where to start? How do we even measure the emissions of software? And how can we possibly reduce them?
In this talk, we explored the latest tools and methodologies that help us to write software which not only makes your users happier, but also stresses the environment a little less.
Save Time, Money, and More With Better Performance
Keynote - International PHP Conference May 2024 - Berlin
Nobody likes slow software. But today’s software projects are often bloated and require the latest hardware just to run acceptably. Why is this? And why do we still accept that?
Slow applications are annoying because they waste time and money, and worse, they contribute to the climate crisis. Yet software development continues to follow only one trend: bigger, heavier, more.
JavaScript and PHP are still the foundation of most websites on the Internet, so let’s roll up our sleeves and do something about it!
Sustyweb - The w3c Guidelines for a Sustainable Web
Developer Week 2024 - Nuremberg International PHP Conference May 2024 - Berlin
The newly released W3C Web Sustainability Guidelines, or sustyweb in short, provide a clear path toward a greener and more environmentally conscious web. Although still a public draft, they already contain much more than the usual recommendations to use green hosting and shrink images. For example, they also cover topics like infrastructure, UX design and product management. In this talk, we will delve into these recommendations and explore how developers can adopt them to reduce the carbon footprint of their web applications.
Navigating the Green Path: Plan A’s Journey to Sustainable IT
EcoCompute 2024 - Munich
At Plan A, it is our daily business to measure and reduce our clients’ emissions. However, we are also a tech company ourselves and face the same challenges in this space, such as blind spots in IT emissions.
To lead by example, Plan A has launched its Green IT initiative in 2024. Our goal is clear: we want to know exactly how many emissions our service generates and aim to reduce those as much as possible.
Sounds great, but where do you start? Join me on the first steps of a young company’s journey towards sustainable software development. What setbacks have we had to overcome? How do you make the most of limited resources? And how to foster a culture of sustainability in the engineering department?
Speed up your code for the planet
PHP Developer Day 2023 - Dresden, Germany
Almost 8 million tons of CO₂ are emitted by data centers in Germany alone every year to bring our software to life. PHP, still the most widely used programming language on the Internet, plays a large part in this.
But even apart from the negative impact on the global climate, slow software is simply annoying, because it costs money and worsens the user experience. That’s why we want to take a close look at our applications.
Even small changes can make a big difference. In this talk, we’ll take a look at what options we have to identify bottlenecks and how we can fix them. But we also want to fundamentally question how we can write software in the future that does not only know one direction: bigger, heavier, more.
Es geht ums Ganze - Warum Green IT jetzt so wichtig ist
**DATEV Coding Festival 2023 - Remote **
We humans have only a short time left to reduce greenhouse gas emissions worldwide to a tolerable level. If we fail to do so, we are threatened with a rise in temperature that will shake the world as we know it to its foundations. It is therefore up to each individual to take action. And yet, especially in IT, the problem still seems to be taking shape only very slowly in people’s minds. But what part does information and telecommunications technology actually play in climate change? And aren’t green electricity and climate compensation completely sufficient? After all, it’s all about bits and bytes.
If it were that simple, we wouldn’t have to talk about it. Green software engineering is not just a necessary evil, but on the contrary a diverse and exciting complex of topics. From more efficient algorithms and the choice of the right components, to optimising the system architecture and building the infrastructure to include the global energy market, there is much to learn that will help us reduce the emissions of software.
And if we look beyond the end of our nose, there are also some opportunities in the product design, there are also some opportunities to reduce the CO₂ footprint of software. Last but not least, our customers and stakeholders expect us to finally address the issue. So what are we waiting for?
With a little help from my friends: Tools for writing state-of-the-art PHP code
International PHP Conference June 2023 - Berlin International PHP Conference October 2023 - Munich
Writing high-quality code gets easier when you use the right tools to help you. In this talk, you will learn about software quality, insightful metrics and useful tools. Particularly if you work in a team, controlling the overall code quality and standards is key for a maintainable project.
The best tools won’t help if they are not used correctly, so we will also address how to integrate them into your workflow. And, of course, the faster you get the feedback, the better—let’s not wait for the CI pipeline, but rather report problems even before the push.
The Green ElePHPant - How to create sustainable PHP applications
International PHP Conference June 2023 - Berlin
The share of global IT on the worldwide greenhouse gas emission is aiming towards 4% per year and continues to grow. The energy consumption of software is not a marginal problem anymore, and we all have to play a part in the climate solution.
But what can we, as PHP developers, do to mitigate the issue and reduce the carbon emission of our applications? In this talk, we’ll discuss which concrete options there are to create sustainable PHP applications already today.
From algorithms, profiling, and performance benchmarks over frameworks and packages to carbon-aware operations, we’ll cover many ways for you to take action and become part of the global Sustainable Software Engineering movement.
Coding against climate change
code.talks 2022 - Hamburg
Die Menschheit stößt weiterhin enorme Mengen an Treibhausgasen aus. Wir Software-Entwickler*innen haben unseren Anteil daran, denn die ganze Hardware, auf der unsere Software betrieben wird, muss auch erst einmal produziert werden und braucht dann in Betrieb mehr als nur Luft und Liebe. Und der Anteil der IT an den Treibhausgas-Emissionen steigt unaufhörlich. Was können wir dagegen tun?
In diesem Talk erläutere ich zunächst, warum es zumindest kurzfristig nicht reichen wird, unsere Rechenzentren mit Ökostrom zu betreiben oder sich durch Klimakompensationen freizukaufen. Da unsere Software immer umfangreicher und leistungshungriger wird, betrachten wir im Rahmen des Sustainable Software Engineering, welche Möglichkeiten es gibt, Energie einzusparen und so die Emissionen zumindest zu reduzieren. Gerade auch trendige Technologien wie Blockchain und NFTs sind in diesem Zusammenhang sehr problematisch. Und, fast noch wichtiger: wir müssen wieder dazu übergehen, unsere Hardware längerfristig zu betreiben.
Da Software-Entwickler*innen oftmals nur Requirements umsetzen, überlegen wir zum Abschluss noch, inwieweit das Product Design seinen Anteil leisten kann. Und auch als User*innen sollten wir uns unserer Marktmacht bewusst werden und unseren Konsum überdenken.
YouTube: https://www.youtube.com/watch?v=spPflIHmxz8
Coding against climate change - Sustainable software engineering
International PHP Conference October 2021 - Munich International PHP Conference June 2022 - Berlin
Mankind is releasing enormous quantities of greenhouse gases, which are continuously heating our planet’s atmosphere. Yet, we as developers can’t do much about it anyway, since after all, we only produce code, and that doesn’t hurt anyone. Isn’t that right?
Of course, it’s not quite that simple. The energy that powers our servers and sends our data around the globe has to be produced somehow. Even though the share of regenerative energy sources continues to increase, every year counts if we want to limit global warming to a halfway tolerable level. We can do a lot more than run our laptops in energy-saving mode or the IDE in dark mode. Of course, we can use more efficient algorithms, but also the system architecture and infrastructure plays a significant role. And, if we think outside the box, there are also some opportunities in product design to reduce the carbon footprint of our users.
YouTube: https://www.youtube.com/watch?v=aAdGNw2JMZw
Reduce Boilerplate Code with PHP 8
International PHP Conference October 2021 - Munich
With PHP 8, some new, quite interesting features have been introduced. Some of these features can even help us remove code like getters and setters that have been necessary in the past to work around the shortcomings in earlier PHP versions. As a benefit, the code will even become more robust and easier to maintain than before.
After the theoretical part, we will have a small live coding session and see how we can shrink a typical PHP class to a fraction of its original size — without losing any features! Is it finally time to get rid of some best practices that we used without question for many years?
YouTube: https://www.youtube.com/watch?v=8TfKDMLvi8I
Frameworkless - the new black?
International PHP Conference June 2021 - Online
Frameworks are undoubtedly helpful. They wouldn’t exist otherwise. Yet are they always necessary? What drawbacks do we blindly accept when we chose our beloved framework again for the next project without even thinking about if it fits the actual problem? And why is it cool to consider oneself a Symfony or Laravel developer instead of a PHP developer?
In this talk we’ll have a brief look at the history of PHP frameworks in general, discuss their good and bad sides and eventually come up with the unthinkable: why not try going without a framework in the first place? We will discover the standardisation that has happened within the PHP ecosystem and how it helps to achieve framework-less applications.
Finally, we’ll have a look at a simple webservice written in Vanilla PHP. We will consider when it is beneficial to use a framework, when we should rather ditch them and if there maybe is a sweet spot in-between both extremes.
YouTube: https://www.youtube.com/watch?v=D3Qvt7YeewU
Refactoring - Change your running system
**Eurostaff Meetup January 2020 - Berlin **
January 2020, when Covid-19 still was some sort of freaky virus going around in China only, I had the please to speak on the Eurostaff Meetup about Technical Debt and Refactoring.
The talk was about my experience with Technical debt, which I also wrote down in this series of articles.
Go here for the slides of my presentation.
Continuous Testing and beyond - Software Quality in Web projects
Test Automation Day Conference 2018 - Berlin
Surely it’s not a new insight, but software with lesser bugs leads to happier customers, non-frustrated developers and eventually increased revenue. So why not just test the heck out of it in the first place?
Well, this still has not yet settled in the DNA of every web developer. This talk is about the options you have if you want to test Web projects in, let’s say, the PHP ecosystem.
Of course it’s not limited to that, as we don’t go into any language details. We start with the the basics, explore what measures might be easiest to use in your project (a bit like these “low hanging fruits” that creepy sales guy keeps babbling about), make a detour on some advanced or probably even exotic testing techniques, have another short stop on Software Quality measures and finally end up with the conclusion that testing simply has to be automated and happen before every single deploy to production. Period.
Read the Slides about Continuous Testing and beyond - Software Quality in Web projects
The Lone Stranger or: You can’t establish Clean Code on your own
Clean Code Days 2016 - Munich
You’d love to use Clean Code principles in your project, but you seem to be all alone in the world? If you try to establish Clean Code all by yourself, you will end with rolling the same boulder up the hill again and again, because you can either start fixing the code of others, or try to keep your code clean and watch the rest of the code rot. Both are options, but not good ones. So what can you do?
This talk can roughly be separated into two parts. Firstly we talk about why you need help to get Clean Code into your products, and provide you some bullet-proof arguments which “the Management” can’t deny. But it’s not only about the Management - you have to convince your co-workers, if there are not yet into it. “But Uncle Bob says…” will not be enough, especially in the PHP world.
Nobody can write perfect code at first; it will always require iterations to improve it. So secondly, we introduce some basic Clean Code related measures, which can be added even to existing projects one by one. Here we’ll see how to generally support the daily development and refactoring process. Starting with relatively simple measures like Code Styling and Code Reviews, over to Automated tests, Code Metrics and finally Continuous Integration.
All examples will be in PHP, or PHP-related. However developers from other languages are more than welcome, as we don’t dive deep into the language features and are happy to learn from others.
Read the Slides about The Lone Stranger or: You can’t establish Clean Code on your own