How to build your own AI developer tools with Claude Code | CJ Hess (Tenex)

02/09/26
Source: Lenny’s Newsletter by Claire Vo. Read the original article

TL;DR Summary of CJ Hess’s Custom AI Tool Flowy Revolutionizes Visual Planning for Developers

CJ Hess, a software engineer at Tenex, created Flowy, a unique tool that converts ASCII diagrams into interactive visual mockups and flowcharts. This approach dramatically improves planning for complex UI and animation workflows compared to traditional text-based diagrams. CJ also employs model-to-model comparison techniques using AI models like Claude and Codex to ensure high-quality AI-generated code. His innovations highlight the early stages of a major shift in how developers collaborate with AI-driven tools.

Optimixed’s Overview: How Flowy Enhances Developer Productivity with Visual AI-Powered Workflows

Introduction to Flowy and Its Developer-Centric Design

Flowy is a custom visualization tool designed by CJ Hess that transforms simple ASCII and JSON-based diagrams into rich, interactive flowcharts and UI mockups. By leveraging this visual approach, developers gain clearer cognitive insights during the planning and design phases, enabling more efficient workflow management, particularly for complex interfaces and animations.

Key Features and Benefits

  • Visual Planning Over ASCII: Flowy moves beyond static ASCII diagrams, providing interactive visuals that improve comprehension and reduce ambiguity in design.
  • Integration with Claude Code: CJ uses Claude Code’s AI capabilities to extend his development environment, allowing seamless generation and manipulation of code based on visual inputs.
  • Model-to-Model Code Review: Employing AI models like Claude and OpenAI’s Codex in tandem enables robust quality assurance through comparative analysis of generated code.
  • Custom Ecosystem Building: Flowy is part of a broader ecosystem that CJ builds around AI tools to accelerate development cycles and bypass typical permission bottlenecks in controlled environments.

Practical Applications and Demonstrations

CJ demonstrated how Flowy converts JSON files into detailed flowcharts and mockups, which can then be directly used to build features. This process reduces translation errors between design and development, streamlining the entire production pipeline.

The Future of Developer-AI Collaboration

CJ Hess emphasizes that tools like Flowy represent just the beginning of a revolution in developer workflows. By integrating AI deeply into the planning, coding, and review processes, developers can expect enhanced productivity, higher code quality, and more intuitive design experiences going forward.