|
 |
👋 Hi, this is Gergely with a subscriber-only issue of the Pragmatic Engineer Newsletter. In every issue, I cover challenges at Big Tech and startups through the lens of engineering managers and senior engineers. If you’ve been forwarded this email, you can subscribe here.
Why Ramp built its own in-house coding agent, Inspect
A fintech company rejected the easy route and homebrewed its own coding agent – and is now a step ahead of coding agents from frontier AI labs. An in-depth look
|
| |||||||||||||||
At a select few tech companies, they write most of their code with their own, custom-built, internal AI coding agents. This is different from most of the industry which uses AI coding agents and harnesses like Codex, Claude Code, Cursor, OpenCode, GitHub Copilot, etc. At Ramp, their own version is called Inspect, while at Block it’s Goose (open source), at Stripe it’s Minions, and River at Shopify.
But why not just use what frontier labs and coding harness AI startups already offer; why take the time and effort?
We reached out to Ramp, a fintech company big on building its internal AI infrastructure, and sat down with the founding team of Inspect and engineering leadership. We talked with CTO Rahul Sengottuvelu, head of engineering Hamid Dadkhah, and Zach Bruggeman, principal engineer and founding engineer of Inspect.
Today, we cover:
What is Inspect? Imagine an AI coding agent running on remote sandboxes with access to most internal data sources, and verifying all backend and frontend changes on the remote machine.
Why build your own background coding agent? Engineers and designers at Ramp were dissatisfied with third-party harnesses: they wanted to run more than a few agents in parallel – which local machines don’t support – to have better frontend tooling, and also faced demand for remote development environments.
How Ramp uses Inspect: coding, bugfixing in Slack, debugging, and building internal agents like code review and incident management on top of the Inspect platform
Tech stack and architecture: React/Vite, Cloudflare Durable Objects, SQLite, Cloudflare Agents SDK, Modal sandboxes.
What makes Inspect so popular? The machine in the cloud is a developer machine, plus it has access to numerous internal integrations via API and MCP.
Inside the sandbox. OpenCode, services for development (e.g. Postgres, Redis, RabbitMQ, Temporal), Chromium, and VS Code Server. Plus, we check out smart tricks to make sandboxes spin up in five seconds or less(!!)
Collaboration & feedback. All Inspect sessions are public and open to collaboration, with no opt-outs allowed. More than 150 people at Ramp have contributed to the project.
If you’re like us, you might wonder what the point would be of building your own harness and investing the time and resources in it, given all the choices already out there. This article sets out to answer that question, to understand why other places chose a similar path, and how a non-AI frontier lab can build more efficient tooling than what the frontier AI labs offer. It looks like the “buy, don’t build” tooling convention might not apply to AI tools!
Let’s get into it.
The bottom of this article could be cut off in some email clients. Read the full article uninterrupted, online.
1. What is Inspect?
Inspect is Ramp’s internal background coding agent, shipped and opened internally last November. Engineers at Ramp can use any tool they want, but 75% of merged PRs are now raised by Inspect; a clear indication that many engineers prefer the tool over others:
 |