Code editors make life easier for programmers. They point out potential errors and visually display written code. However, most applications lack information on how efficient and sustainable the written lines, the finished programme or the website ultimately are.
The Carbonara tool from Climate+Tech can be integrated as a plug-in in VSCode-based editors such as VSCode and Cursor. Or, coders can run the programme in the background via the command line. Carbonara generates a forecast of the approximate carbon footprint of the application during coding. According to Carbonara founder Christian Woerle, the idea behind this is:
“Provide information as early as possible [for sustainable optimisation], before further costs are incurred or nothing can be changed.”
How does the tool work?
Carbonara was launched in June 2025. Interested parties can already download the tool free of charge, including recommendations for code optimisation. Anyone who would like to use the analysis tool can access the code via GitHub or install the plug-in in the VSCode Marketplace. However, project manager Christian Woerle points out that “help in solving any problems is expressly welcome”. This can be done via the Carbonara homepage, where users can provide feedback via a simple contact form.
Once installed, Carbonara provides an assessment of the expected digital carbon footprint of an application or website, based on its code. Daniela Grau from Carbonara explains to RESET how this works:
“Sustainable code can avoid certain patterns that are less efficient than others. These can be so-called ‘performance issues’, i.e. changes that make the code faster. Or, other aspects, such as centralising computing power at a location that has a green electricity mix.”
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Depending on how many fossil fuels are included in the mix, the website is then displayed in smaller, which is more energy-efficient.
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There is a very simple reason why Carbonara considers these aspects during coding. “If you want to know exactly how much energy code consumes under which conditions, the finished application ideally needs to be analysed in operation using special libraries,” said Grau. At this point, however, “five or six-figure sums” have often already been spent. This means that the code can only be optimised and not completely rewritten. Because of this, Carbonara allows companies to integrate green coding practices right from the start.
Carbonara tests according to recognised standards
For its analysis, Carbonara uses, among other things, a database of “green software patterns” from the Green Software Foundation. Since 2021, the foundation has been providing programmers with design patterns for lines of code already tested for sustainability. Or, as the Green Web Foundation puts it: “Your software’s emissions will be reduced if you use our design patterns.”
However, Carbonara’s review can also be applied to existing applications and websites. According to Daniela Grau, “Carbonara integrates tools at various levels.”
This would allow external websites to check “what amounts of data are being transferred and on which network they are running,” which is the top layer of optimisation. “Code patterns or server configurations can be improved in depth.”
When asked how much emissions could be saved as a result, Christian Woerle replies: “20-30 percent, depending on the region and estimate, so a very significant amount. The nice thing is that in IT, most of these savings can be achieved without anyone having to sacrifice anything, simply through efficiency gains and relocation.”
The design of modern code no longer only affects the device that displays the website or runs an application. Use cases such as streaming service apps show that comparatively lean programmes make massive use of data centres‘ databases—consuming a great deal of energy and water in the process.
However, the fact that applications outsource computing operations or information to cloud servers makes it all the more important to optimise software for sustainability. The Sustainable Games Alliance explained to us that small changes—such as reducing the resolution of an animation in the menu—can have a huge impact on reducing the computing load on servers.
Does sustainable code have disadvantages?
There are generally no disadvantages for users. “Uncompressed images are actually an area where the average website can massively reduce data transfer and thus save CO2 emissions. As a rule, the compression should not be noticeable to the human eye. […] Where compromises make sense is with complex ‘gimmicks’ or animations in the front end,” explains Daniela Grau.
How can we ensure a green digital future?
Growing e-waste, carbon emissions from AI, data centre water usage—is rampant digitalisation compatible with a healthy planet? Our latest project explores how digital tools and services can be developed with sustainability in mind.
However, sustainable programming could become even less of a priority in the coming years. So-called ‘vibe coding’ is becoming increasingly popular with AI tools such as Claude Code and Google’s Gemini CLI. This means that not only developers who can at least understand the code they create, but anyone with internet access has the opportunity to create websites and programmes. However, the code designs created by language models are not sustainable. “In mid-2025, a study classified [AI]-generated code as significantly more CO2-intensive,” says Carbonara. However, the Climate+Tech team believes its database can help integrate green coding practices in AI-generated code in the future.
