Simplex is achieving a 70 percent reduction in screen development time by using OpenAI’s Codex as its primary coding agent, a significant increase in productivity that reflects a commitment to AI-native software creation. The technology partner established an AI “center of excellence” after ChatGPT launched to create the foundations for employees to use AI and to validate AI-native development processes. This deliberate approach allows Simplex to accelerate development and build internal expertise in AI-driven workflows, moving beyond assistive tools to delegate multi-step tasks directly to artificial intelligence. “We rolled out Codex across the company for three reasons,” explains Kazuya Ujihiro, Executive Principal at Simplex, “First, our internal evaluation showed it offered the best balance of cost, accuracy, and functionality.” Through initial testing on CRUD-based web applications, Simplex also measured a 40 percent decrease in screen design time and a 17 percent reduction in internal integration testing.
Codex & ChatGPT Enable AI-Driven Systems Development
Unlike many organizations still experimenting with AI as an assistive tool, Simplex designated Codex as its primary coding agent, signaling a full integration into its systems development processes. The company’s approach extends beyond simple code generation, with Codex now utilized across design and testing phases, including generating front and back-end code directly from design documents and creating comprehensive unit tests. Simplex is also actively validating automated workflows, running Python scripts from the Codex CLI to continuously move from server implementation to resolving issues identified in end-to-end tests. After ChatGPT launched, Simplex established a center of excellence to create the foundations for employees to use AI and to validate AI-native development processes. We also wanted to define a primary agent so we could accumulate and share usage know-how more efficiently.
Third, it was easier to expand safely and quickly based on our ChatGPT Enterprise seats. These efforts are not simply about accelerating existing processes, but fundamentally rethinking software development itself. Ujihiro notes that “Codex does more than help teams write code faster; it converts design know-how and review expertise into something AI can use, turning individual knowledge into a repeatable organizational advantage.” The company envisions a future where AI can autonomously generate products from requests for proposals, provided databases, API catalogs, and design rules continue to mature.
Simplex Validates AI Impact with Quantitative Measurements
Simplex, a technology partner specializing in consulting and systems development, is moving beyond experimentation to demonstrate measurable gains from integrating artificial intelligence into its software development workflows. This deliberate approach has yielded significant results, with the company now reporting a 70 percent reduction in the time required to develop each screen using OpenAI’s Codex, a quantifiable improvement over traditional methods. Building on that experience, Simplex established a center of excellence to create the foundations for employees to use AI and to validate AI-native development processes. The company’s evaluation process revealed Codex offered the best combination of cost, accuracy, and functionality. Beyond simply accelerating code creation, Simplex is leveraging Codex throughout the entire development lifecycle, including design, testing, and even remediation of nonfunctional requirements. Ujihiro emphasizes that the benefits extend beyond mere engineering hours saved, highlighting a shift towards a model where senior expertise can be more broadly applied.
We rolled out Codex across the company for three reasons. First, our internal evaluation showed it offered the best balance of cost, accuracy, and functionality. Second, we wanted to define a primary agent so we could accumulate and share usage know-how more efficiently. Third, it was easier to expand safely and quickly on the basis of our ChatGPT Enterprise seats.
Kazuya Ujihiro, Executive Principal, Simplex
This figure isn’t theoretical; it stems from practical application within Simplex’s projects focused on CRUD-based web applications, and builds on an earlier initiative where a center of excellence was established after ChatGPT launched to create the foundations for employees to use AI and to validate AI-native processes. Ujihiro emphasizes that Codex’s impact extends beyond mere speed.
Codex does more than help teams write code faster. It converts design know-how and review expertise into something AI can use, turning individual knowledge into a repeatable organizational advantage. People retain final judgment and accountability for quality, while AI handles implementation, validation, and fixes at speed. As that division of labor becomes standard, it will improve not only development speed, but the total value we can deliver to customers.
Kazuya Ujihiro, Executive Principal, Simplex
Simplex is demonstrably altering software development timelines through a commitment to artificial intelligence, achieving a 70 percent reduction in screen development time using OpenAI’s Codex, a figure indicative of substantial gains beyond theoretical improvements. The shift extends beyond simply accelerating code writing.
Codex has made it easier for smaller teams to move design work forward, and it has improved the accuracy of reviews for specifications across multiple files. It is also helping us build a model where senior expertise can be applied more broadly across development. As a result, roles are becoming clearer on the ground: people focus on final decisions and accountability for quality, while AI handles implementation, review, and fixes.
