# Kurt Mackey steps down as Fly.io CEO in agent-compute reset > Source: > Published: 2026-07-25 22:56:45+00:00 [Kurt Mackey (@mrkurt)](https://twitter.com/mrkurt) is stepping down as chief executive of [Fly.io](https://fly.io/), handing control of the cloud infrastructure provider to former Docker CEO Scott Johnston as Fly.io redirects its product and capital toward computers built for AI agents. Mackey will remain on Fly.io's board and move into an advisory role, according to [his July 24th announcement](https://fly.io/blog/kurt-scott-money-sprites/). The leadership change comes with a $25 million Series D and an explicit decision to make [Sprites](https://fly.io/sprites), Fly.io's persistent computing environments for agents, the center of the business. The move closes an eight-year operating run for a founder whose career has tracked successive generations of developer infrastructure. Mackey ran technology at Ars Technica for eight years before helping build MongoHQ, later renamed Compose, which IBM acquired in 2015. He started Fly.io around two ideas: applications should run close to their users, and cloud infrastructure should combine AWS-like flexibility with Heroku-like usability. Mackey now argues that AI coding agents have weakened both parts of that original pitch. Agents can navigate complicated infrastructure without the carefully designed developer experience Fly.io spent years building, while AI-generated software may increasingly serve smaller, more specialized audiences than the conventional applications Fly.io was designed to host. "Fly.io has been motoring along this year, but I've coasted a bit, letting the company smolder in an unresolved identity crisis," Mackey wrote. Fly.io says it has recorded its strongest financial months and quarter to date, though it has not disclosed revenue or profitability. ### A succession tied to the product reset Johnston's appointment follows discussions with Mackey that began in 2025. Mackey said Fly.io had reached a stage where his experiment-driven management style was producing diminishing returns, and that Johnston had a stronger playbook for converting the infrastructure Fly.io built into a scaled business. Johnston ran Docker for roughly five years before [leaving on February 12th, 2025](https://www.docker.com/press-release/docker-announces-don-johnson-as-new-ceo-succeeding-scott-johnston/). He had joined Docker in 2014 as its first product manager and later served as chief operating officer and chief product officer. His tenure as CEO covered Docker's recovery from a period of financial and strategic strain after the company sold its enterprise business in 2019 and narrowed its focus around developer tools. That history explains the hire. Fly.io has spent years presenting itself as a simpler alternative to the large public clouds, originally describing the product in its [Y Combinator application](https://www.ycombinator.com/companies/fly-io) as a "Global Heroku." The latest shift asks Johnston to repeat a familiar exercise: preserve developer adoption while building a commercial identity around a narrower product thesis. Mackey will continue working on product design and technical direction, areas where he has remained deeply involved. He said a review of Fly.io's codebase shows his name attached to more lines than any other contributor. Johnston is joining Fly.io's board in addition to becoming CEO. ### The $25 million round Fly.io described the financing as a $25 million Series D co-led by [Dell Technologies Capital](https://www.delltechnologiescapital.com/companies?07f11d2f_page=2) and [Intel Capital](https://www.intelcapital.com/fly-io-doubles-down-on-computers-for-agents-with-25m-to-deliver-the-next-generation-of-ai-infrastructure/). [Andreessen Horowitz](https://a16z.com/announcement/investing-in-fly-io/), [EQT](https://eqtgroup.com/about/current-portfolio/fly-io), [Geodesic](https://geodesiccap.com/portfolio/) and Y Combinator also participated. A16z general partner Martin Casado and Dell Technologies Capital managing director Daniel Docter are joining Fly.io's board. The headline amount follows a regulatory disclosure that showed a slightly smaller figure. [RuntimeWire reported on July 22nd](/article/fly-io-23-million-equity-offering-sec-filing) that Fly.io had sold $23.2 million of a planned $25 [million equity offering](/article/funding-u-6-million-equity-round-2-7-million-cash). The filing did not identify the investors, round label or valuation. Fly.io's announcement did not disclose a valuation or explain the difference between the amount reported as sold in the filing and the $25 million Series D. The financing follows the $70 million Series C led by EQT Ventures that Fly.io disclosed in 2023. Fly.io said it had been close to reaching a point where it would not require further outside capital under its previous plan. The agent-infrastructure push changed that calculation, according to Mackey. Fly.io says more than 37,000 customers use its infrastructure, including over 8,000 it categorizes as agent-native. The company also claims revenue from its largest agent-native customers grew nearly twelvefold over the past 12 months, and that agent-native businesses account for about two-thirds of revenue among its largest customers. Fly.io did not disclose the number of customers included in that cohort, the revenue base behind the growth rate or companywide revenue. Those omissions matter because Fly.io is using a subset of its customer base to justify a companywide redirection. The disclosed figures show agent workloads gaining importance inside Fly.io; they do not establish how large the Sprites business is on its own. ### Fly.io's bet on persistent agent computers Sprites are hardware-isolated Linux environments designed to give coding agents persistent state without requiring customers to maintain conventional servers. Each environment has a thin-provisioned disk of up to 100GB, can sleep when idle, and supports checkpoints that restore its filesystem to an earlier state. Fly.io charges for actual compute and storage usage rather than keeping the meter running while a Sprite is inactive. The latest iteration adds a Sprite Block Device that can fork a template drive into many copies, along with Connectors that let an agent make authenticated requests to outside services without receiving the underlying credentials. Fly.io says these were its most requested additions and that some agent companies had continued using its lower-level Fly Machines because Sprites lacked them. Fly Machines and Fly.io's existing application-hosting service will remain available. The change is in resource allocation: Sprites began as a skunkworks project run by a small internal group, while Mackey now says computers for agents will define Fly.io's product direction. The distinction Fly.io is selling is persistence. Short-lived sandboxes work for isolated code execution, while agents performing longer tasks need files, installed packages and application state to survive between sessions. Fly.io is betting that those workloads will require large fleets of inexpensive, recoverable computers that can pause when idle, resume quickly and connect safely to production systems. Johnston inherits a company with a functioning cloud platform, substantial prior funding and claimed demand from agent-focused customers. He also inherits Mackey's decision to narrow Fly.io around a market whose architecture and buying patterns remain unsettled. The Series D gives Johnston capital to make that bet operational. Mackey's departure from the CEO role makes him accountable for the technical thesis without requiring him to run the company built around it.