Rezonant, the London startup founded by former Stripe UK CTO Emma Burrows (pictured), has launched out of stealth with a product development workspace for teams building with AI coding agents.
The company, previously backed by General Catalyst and Firstminute Capital to the tune of $6 million dollars in Seed funding, is opening signups today after several months in a private beta.
Rezonant’s pitch is that AI has made code dramatically faster to produce, but it has not made teams any better at deciding what to build, which has created a huge new bottleneck in software development.
“Coding agents have made software delivery much, much faster,” Burrows told Pathfounders. “For the past 20 years, we have evolved all of these processes to basically allow us to deal with the fact that engineering is incredibly expensive. But now that coding is almost the fastest bit of the whole process, that has really turned a lot of things on its head.”
Rezonant is designed to sit above tools such as Cursor, Claude Code and GitHub Copilot. It gives product managers a live, multiplayer workspace where they can turn product ideas into structured specs and tasks that AI coding agents can execute, grounded in the codebase, rather than floating around in ideas sketched in Notion, Linear, Slack and Figma.
The startup’s argument is that the old product workflow is starting to creak. Product managers are still writing specs in Notion or Google Docs, translating them into tickets in Linear, checking designs in Figma, referencing meeting notes, and trying to make sure engineers understand the original intent. Meanwhile, some of those ‘engineers’ are gradually becoming AI agents.
“There’s this squeeze point for product managers, and the ratio of product managers to engineers is changing,” Burrows said. “A lot more is being asked of them. And so they need to be able to do their jobs as sped up as engineers, if not more, so that they don’t get dragged into just building, you know, basically slop.”
This means that Rezonant is not so much another documentation tool as a control layer for the age of AI-assisted software development.
“The PMs are the real drivers of the strategy, of the kind of technical products, and they need tooling to help them do that,” Burrows said. “So that’s why we built Rezonant.”
This first release helps teams write PRDs and product briefs from the tools they already use. Its Chrome extension, Rezonant Alter, allows a product manager to literally talk through a feature idea with their voice, naturally. Rezonant then turns that into a structured product document, pulling in context from the codebase and connected tools such as GitHub, Notion, Figma and Granola.
Burrows said the voice was not a gimmick, but a way of capturing how product people actually think.
“You talk to the product and describe it out loud,” she said. “Because it’s such a natural way of working that product managers are used to, it’s a very natural thing for them to do. But also because of the way you naturally think and talk… it actually captures a lot more of the nuances of the right material.”
That material then becomes the training for the downstream agent.
“It’s the voice piece,” Burrows said, “but it’s also understanding the context of what you’re looking at, what you’re pointing at, and then connecting that with the codebase is really the big unlock for us.”
Burrows also said writing for agents is not the same as writing for strong human engineers.
“I think agents need more specification than your average excellent engineer,” she said. “You don’t want any grey area in terms of what they are being asked to do, because they will run with that. And you’ll end up with garbage at the end in many cases.”
That insight puts Rezonant in a early category: AI-native product management and specification tools. Its competitors are not so much single companies as the existing stack product teams have glued together such as Notion, Google Docs, Linear, GitHub, Figma, Slack and the coding agents themselves. There are also emerging AI-native spec tools such as ChatPRD.
That said, Burrows expects the market to become more crowded.
“I think it will be a hot space,” she said. “There’s no doubt about that. As a startup, one of the most important things is timing. Have you entered the market at the right time and then can you keep pace with the changes? Which right now in AI is a pretty big challenge.”
Linear’s recent declaration that “issue tracking is dead” is part of the same shift towards agents. If coding agents accelerate engineering, then task tracking, product scoping and engineering refinement are all up for grabs.
Burrows said Rezonant originally grew out of the human process of engineering refinement: taking a vague product idea and breaking it into small, shippable chunks. But agents have made that process more important.
“For coding agents, it’s actually much closer to that process,” she said. “You don’t want any grey area.”
The company will charge through a seat-based SaaS model with usage credits. The standard business tier is expected to be around $25 per seat, with additional credits for teams that want to run more development through Rezonant.
The longer-term vision is more ambitious than better PRDs. Burrows says she wants Rezonant to become infrastructure for product development automation, letting companies decide which parts of the workflow they want to automate while retaining control.
“The long-term vision really is to build on top of that and build much more automation,” she said. “So any company can decide what they want to automate in this flow, end to end, and do it with control.”
That raises issue of teams shipping software so fast it starts to degrade. Burrows thinks that may be the next big problem.
“I think we’re going to see over the next six months a trend where companies shipped too fast,” she said. “If you can do that, then where does the gate on quality sit? Products need to think hard about where they want to allow things to happen very quickly, and whether they want to be more deliberate, so that they end up with the product that’s actually coherent and elegant, rather than just a mess. I think they'll be a lot of experimentation on that front.”
