Tessl raises $125M at $500M+ valuation to build AI that writes and maintains code


Many startups and larger tech companies have taken a crack at building artificial intelligence to code software. Now, another new player is coming out of the shadows to throw its hat into the ring, with a mission to fix the many problems that will arise when humans and all those AIs are all writing code together.

Tessl is building what it describes as an “AI native” platform that developers and their teams can use to create and maintain software, and on Thursday it opened up a waitlist for those interested in trying it out. 

We say “is building” for a good reason: Tessl’s product has yet to launch, and the plan is to have it ready early next year. But the London-based startup is now sharing a bit more about what it’s doing with some financial fanfare: Tessl has quietly raised $125 million across a seed round and a Series A, both being announced for the first time today. The latest round is led by Index Ventures, with Accel, GV, and Boldstart participating. GV (aka Google Ventures) and Boldstart co-led the seed round.

TechCrunch has confirmed with multiple sources that Tessl’s post-money valuation is north of $500 million.

As you might have surmised, one reason why a company without customers nor a shipped product is getting this kind of attention from top-shelf VCs is because of who is building it. 

Tessl’s CEO and founder is Guy Podjarny, a developer whisperer of sorts. His last startup was Snyk, a cybersecurity firm that was last valued (in 2022) at $7.4 billion. Before that, he was the CTO of Akamai, a role he took after Akamai acquired his first startup, Blaze, which focused on speeding up website loading times. 

“Podjarny is incredibly visionary and thoughtful about his business,” said Carlos Gonzalez-Cadenas, the partner at Index who led the investment. “He’s very, very good [at understanding] developer communities and building developer-oriented businesses.”

Podjarny said in an interview that the concept for Tessl arose from his experience at Snyk. 

Snyk focuses on detecting (and fixing) security vulnerabilities in code, and Podjarny observed that a similar issue was becoming more urgent with code and software interoperability overall — in particular because of the rapid expansion of code written automatically by AIs. 

“What is AI doing to software development?” he recalled asking himself. The answer was: speeding it up, but also creating much more of it automatically. The process of maintaining and shipping updates to that code would compound the complexity and chances of systems breaking. This ends up having a lot of bad implications (security, uptime, cost, efficiency) for organizations. “The more that picture formed in my mind, the more I knew I would build this,” he said.

The startup’s name, Tessl, is a reference to “tessellation,” Podjarny said, as it aims to make sure that software and the code behind it fit neatly together, rather than exist in a messy, overlapping jumble.

Podjarny was cagey about what kinds of applications or code he envisions being built, or maintained, on Tessl. But it sounds like it will actually start small.

“We’re not sharing the full strategy yet on what that is,” he said of target applications or use cases. “I would say that we’re not starting with games. We’re starting with relatively simple software that allows us to build an end-to-end system that is more manageable for LLMs to generate, and more manageable for humans to specify. And we will evolve from there.” 

The basic idea behind the startup goes something like this: Developers and their teams (which include product managers and others who don’t code) can provide specifications to Tessl in the form of natural language or code. Tessl will then write code to match those specifications.

Teams can test that code in a sandbox, where issues can be flagged and addressed, and continue to modify specs as needed. After that, Tessl can be automated to maintain that code to that specification. So if something else risks breaking because of the new code, Tessl will run remediation to identify and fix that. 

It sounds like Tessl is not being conceived as a walled garden. Podjarny said he’s talking to others who have built or are building AI coding assistants, with the idea that these other platforms’ work will also be maintainable using Tessl.

It sounds like Tessl is not being conceived as a walled garden. Podjarny said that he’s talking to others that have built or are building AI coding assistants, with the idea that the work these other platforms produce will also be maintainable using Tessl. This means that while it theoretically will compete with the likes of Anysphere’s Cursor, Poolside, GitHub’s Copilot, Magic, Codeium, Augment, OpenAI, IBM and many more, it could potentially also work with whatever a team is using.

The startup will initially aim to support Java, Javascript and Python, and would add more languages over time, Podjarny added. 

One reason why investors love the idea and are backing it is because of that extensibility. Maintaining code is something that has “a lot of signal” as being important right now, said Gonzalez-Cadenas. “But he’s building a system of record here,” he added. “Once you do that, there is a variety of opportunities.”


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