Flow Engineering raises $23M Series A from Sequoia to bring agile software practices to hardware design
Oct 14, 2025 with Pari Singh
Key Points
- Flow Engineering raises $23 million Series A from Sequoia to apply agile software practices like continuous integration to hardware design for aerospace, defense, and nuclear companies.
- The startup's internal tool compressed hybrid rocket engine design from 12 weeks to two hours, validating demand from fast-moving El Segundo clusters like SpaceX and Joby Aviation.
- Flow deliberately targets next-generation hardware makers over legacy primes like Boeing, mirroring GitHub's early strategy of building around innovators rather than incumbents.
Summary
Flow Engineering has closed a $23 million Series A led by Sequoia Capital, backing its bet that the hardware design industry is undergoing the same workflow transformation that reshaped software development two decades ago. The company, founded by Harry Singh, a mechanical engineer who previously worked at BAE Systems and BP, builds a collaborative development platform targeting next-generation aerospace, defense, and nuclear companies.
The core product functions as a single source of truth for requirements and systems design, with continuous integration between the two layers. The analogy to software engineering is deliberate: where agile replaced waterfall in software, Flow argues the same transition is now underway in physical product development, where requirements and designs shift daily rather than being fixed at project outset.
Flow's origin is operationally credible. Singh's prior venture, a hardware consultancy called The Rocket Company, built the platform internally to compress hybrid rocket engine design timelines. Where the industry's best teams needed 12 weeks to move from requirements to detailed design, the internal Flow platform achieved the same output in two hours. That internal tool became the commercial product.
El Segundo, California is the company's primary market, representing roughly 70% of its customer base. Singh identifies the cluster of SpaceX, Nanduro, Joby Aviation, and Archer as representative of the new hardware development paradigm, companies that design iteratively and bottom-up rather than through traditional top-down waterfall processes. Flow explicitly turns away legacy primes like Boeing and Airbus, drawing a direct parallel to how GitHub built its early base around Google and Facebook rather than IBM and Oracle.
The company's path to El Segundo was indirect. Flow launched from London and initially sold into European legacy aerospace, where Singh says customers admired the vision but didn't adopt the software. The El Segundo market found Flow organically and pulled it into the new workflow. That inbound dynamic from a concentrated, fast-moving customer cluster is now the growth engine.