Tessl

London-based Tessl is building an 'AI-native' approach to software development, generating secure, maintainable code from natural-language specifications. Its bet is on spec-driven development, where the specification - not the code - becomes the durable source of truth that AI keeps in sync. Founded in 2024 by serial entrepreneur Guy Podjarny, it launched with significant funding and considerable attention. It is among the startups arguing that AI will reshape not just how code is written but how software is fundamentally structured.