---
title: "AI didn't write our SDK. It changed how we built it."
description: "Stripe's extensibility SDK was built with AI involved across prototyping, architecture, implementation, and refinement, but the main change was to the development loop rather than code-generation speed. For a custom-object design, one engineer produced a working prototype, demo, and documentation site in roughly two days instead of an estimated two to three weeks, allowing the team to evaluate boundaries and reprioritize the feature for the next major launch. The team then used reviewed, detailed specifications and persistent domain guidance to delegate bounded work, including about twenty ESLint rules covering authoring constraints such as sandbox boundaries, imports, and type safety. AI also helped keep scripts, workflows, SDK generation, runtime enforcement, tooling, documentation, examples, and tests aligned, while human judgment remained responsible for abstractions and trade-offs. The post concludes that AI's leverage came from making more artifacts concrete earlier, enabling earlier feedback and a tighter deliverable."
---

# AI didn't write our SDK. It changed how we built it.

[Stripe](https://yomu.fyi/company/stripe) · Mike North · Aug 28, 2026

**Type:** Explainer

## Summary

Stripe's extensibility SDK was built with AI involved across prototyping, architecture, implementation, and refinement, but the main change was to the development loop rather than code-generation speed. For a custom-object design, one engineer produced a working prototype, demo, and documentation site in roughly two days instead of an estimated two to three weeks, allowing the team to evaluate boundaries and reprioritize the feature for the next major launch. The team then used reviewed, detailed specifications and persistent domain guidance to delegate bounded work, including about twenty ESLint rules covering authoring constraints such as sandbox boundaries, imports, and type safety. AI also helped keep scripts, workflows, SDK generation, runtime enforcement, tooling, documentation, examples, and tests aligned, while human judgment remained responsible for abstractions and trade-offs. The post concludes that AI's leverage came from making more artifacts concrete earlier, enabling earlier feedback and a tighter deliverable.

## Context

Platform SDK work is constrained by abstraction and coordination problems: teams must decide how developer experiences should feel, where boundaries belong, which concepts belong in the model, and how multiple product surfaces can remain coherent. Sequential cycles make prototypes, detailed specifications, and feedback expensive, so teams often evaluate ideas later and with less concrete evidence.

## Approach / What changed

The team used AI to create a working custom-object prototype, articulate architectural implications, draft reviewed implementation specifications, and provide persistent domain guidance for delegated work. Agents implemented bounded tasks only after specs were reviewed, with output checked against architectural intent. AI was also used for edge-case exploration, bug reproduction, documentation and example updates, targeted tests, and final-mile refinement.

## Takeaways

- A custom-object prototype with a demo and documentation site was built in roughly two days, replacing an estimated two-to-three-week effort and moving discussion from speculative feasibility to concrete evaluation.
- The spec-first workflow had agents draft detailed GitHub issues before implementation; the team used it to produce roughly twenty ESLint rules with explicit scope, correctness criteria, type-checking requirements, and auto-fix behavior.
- AI did not replace architectural judgment and could produce locally plausible output that violated deeper invariants, making review discipline and persistent domain guidance necessary.

**Tags:** [Architecture](https://yomu.fyi/topic/architecture), [Developer Experience](https://yomu.fyi/topic/developer-experience), [Performance](https://yomu.fyi/topic/performance), [TypeScript](https://yomu.fyi/topic/typescript)

- Source: [Stripe](https://stripe.dev/blog/ai-didnt-write-our-sdk-it-changed-how-we-built-it)
- Source URL: https://stripe.dev/blog/ai-didnt-write-our-sdk-it-changed-how-we-built-it
- Ingested by Yomu: 2026-08-29T12:00:54.028Z

[Read original post](https://stripe.dev/blog/ai-didnt-write-our-sdk-it-changed-how-we-built-it)