For programmers, building a new application is never as simple as writing the code. That's because most software depends on other software, such as database management systems, to work. Just because an application works on your laptop doesn't mean it will work well on your company's data center, which might lack some of the software it depends on.

Investors have poured hundreds of millions of dollars into startups like HashiCorp and GitLab that try to streamline the process of getting applications ready to run in data centers. One of the most prominent of these is Docker, which popularized "containers," a technology that makes it easier to bundle up software to run in the cloud.

But Docker cofounder Solomon Hykes believes the technology he built the company around will soon be eclipsed by a newer technology for building portable applications known as WebAssembly, or "WASM" for short. Hykes and others think WASM is a faster and more secure alternative to traditional containers. Had WASM been around in 2008 when Hykes and company built Docker, they "wouldn't have needed” to create Docker, Hykes tweeted in March. "That's how important it is."

Hykes, who stepped down as CTO of Docker last year but is still on the company's board, isn't exactly a neutral party. He's an investor in a WASM-focused startup called Wasmer. And he quickly followed his initial tweet to say Docker might someday support WASM applications. Docker did not respond to a request for comment.

He's not the only one who sees promise in the new technology. Mozilla and other web browser makers introduced WASM in 2017 as a new way to create applications that run in all major browsers, including Chrome, Firefox, and Safari. But it’s also being used to create applications that run outside of browsers. For example, cloud computing companies Fastly and Cloudflare now let customers run WASM applications on their servers.

It's still early days for WASM. Only a few languages, including C, C++, and Mozilla's Rust are currently supported. Cloudflare only recommends using WASM on its service for narrow, computing heavy uses, such as audio processing or resizing images, not for building full-blown applications. But Wasmer founder Syrus Akbary believes it will eventually become a universal computing platform, fulfilling Java's 1990s "Write once, run anywhere" marketing tagline.

Java lived up to that promise, to an extent. But as application development has grown more complex, developers now face challenges beyond ensuring that an app runs on multiple hardware architectures and operating systems. One is the need to install and configure additional software to make an application work properly. Docker and similar tools tackle that problem. But Fastly CTO Tyler McMullen says previous technologies designed to make applications more portable tend to create a trade-off between security and performance. WASM, he says, doesn't require such compromises. "We looked at existing technologies and nothing else fit our needs," he says.

WASM's benefits stem from its origins as a browser technology. Browsers now exist for practically every computing device you can think of. Browser makers and web-standards bodies have spent years ensuring that web developers can write code that will work on practically any standards-compliant browser, regardless of the end user's hardware and operating system. Browser makers have also taken pains to keep websites’ code isolated from your device’s operating system and even from other websites you might have open.

WASM started as a way for developers to write software that runs in the browser using languages other than JavaScript, the standard language for code that runs in a browser. Over the years JavaScript has evolved into a powerful language that can create complex desktop-like applications such as Google Docs, but it still has its limitations. Performance is a big one.