Edwin Morris, a designer at Jane Street, reports a fundamental shift in his professional workflow by replacing traditional design tools like Figma with Claude for software prototyping. Previously, Morris relied on static documents and mockups, but since joining the firm in the summer of 2025, he has transitioned to building functional prototypes directly within the codebase. This approach allows him to test interactive features—such as adding LLM prompts to the internal JSQL query language—and iterate rapidly without the overhead of manual design-to-development handoffs.

The author notes that his reliance on Figma has declined significantly over the past 2 months as he gains proficiency with Claude for larger-scale implementation tasks. He describes using the model to generate 2000+ line diffs (code changes) and implementing new application features that bypass traditional mockup phases entirely. By creating working proofs of concept, Morris claims he can better validate user needs and technical feasibility, allowing teammates to interact with a tangible product rather than a theoretical proposal.

Despite the efficiency gains, Morris identifies potential drawbacks in this new design-as-code methodology. He expresses concern that relying on AI models may trap him in an iterative mindset, potentially limiting his capacity for fluid, creative exploration of entirely new concepts. Additionally, he highlights challenges in team collaboration, as reviewers receive a near-complete feature rather than a preliminary wireframe. To manage this, the design team at Jane Street currently treats prototypes as disposable 'living proposals' where the code serves as a vehicle for design and user experience feedback before a formal production implementation is created by engineers.

Morris observes that this shift has allowed him to engage with technical mediums again, a practice he had largely moved away from after specializing in design documentation as frontend development grew more complex following 2011. Even without expertise in Jane Street’s specific stack—OCaml and Bonsai (a reactive UI library for OCaml)—he finds the model's support indispensable for contributing to the real artifact. He concludes that while the team is still adjusting to the workflow, the ability to build functional prototypes directly has empowered him to explore ideas that would have previously been deemed too risky or time-consuming to prototype.

Edwin Morris, a designer at Jane Street, reports a fundamental shift in his professional workflow by replacing traditional design tools like Figma with Claude for software prototyping. Previously, Morris relied on static documents and mockups, but since joining the firm in the summer of 2025, he has transitioned to building functional prototypes directly within the codebase. This approach allows him to test interactive features—such as adding LLM prompts to the internal JSQL query language—and iterate rapidly without the overhead of manual design-to-development handoffs.

The author notes that his reliance on Figma has declined significantly over the past 2 months as he gains proficiency with Claude for larger-scale implementation tasks. He describes using the model to generate 2000+ line diffs (code changes) and implementing new application features that bypass traditional mockup phases entirely. By creating working proofs of concept, Morris claims he can better validate user needs and technical feasibility, allowing teammates to interact with a tangible product rather than a theoretical proposal.

Despite the efficiency gains, Morris identifies potential drawbacks in this new design-as-code methodology. He expresses concern that relying on AI models may trap him in an iterative mindset, potentially limiting his capacity for fluid, creative exploration of entirely new concepts. Additionally, he highlights challenges in team collaboration, as reviewers receive a near-complete feature rather than a preliminary wireframe. To manage this, the design team at Jane Street currently treats prototypes as disposable 'living proposals' where the code serves as a vehicle for design and user experience feedback before a formal production implementation is created by engineers.

Morris observes that this shift has allowed him to engage with technical mediums again, a practice he had largely moved away from after specializing in design documentation as frontend development grew more complex following 2011. Even without expertise in Jane Street’s specific stack—OCaml and Bonsai (a reactive UI library for OCaml)—he finds the model's support indispensable for contributing to the real artifact. He concludes that while the team is still adjusting to the workflow, the ability to build functional prototypes directly has empowered him to explore ideas that would have previously been deemed too risky or time-consuming to prototype.