Hacker News: Zakodiac

Show HN: Mockd – Mock Server for HTTP, gRPC, GraphQL, WebSocket, MQTT, SSE, Soap

Zakodiac — Wed, 25 Mar 2026 12:59:16 +0000

I kept ending up running WireMock for REST, some random Node for WebSocket, a hacky gRPC mock and whatever else I needed ad-hoc. So I built one that does all of them. The core is a shared engine (matching, state management, templates, chaos injection) and each protocol is just another interface on top of it. Once that clicked it got fun to add more. The part I'm most interested in feedback on: digital twins. You import a real API's OpenAPI spec, bind endpoints to stateful tables, and get a mock that behaves like the real service. stripe-go runs 49/49 tests against mockd. twilio-go passes 13/13.

As all things tend to start from annoyance, I built this because I got annoyed while at a client with a normal modern stack that integrates with legacy bank SOAP APIs. Your options were basically spin up WireMock or don't test it... Sooo ~120K lines of Go late .. I built mockd, no CGO, Apache 2.0. Single binary, 12ms startup.

Comments URL: https://news.ycombinator.com/item?id=47516758

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New comment by Zakodiac in "Software factories and the agentic moment"

Zakodiac — Sun, 08 Feb 2026 06:05:24 +0000

The Digital Twin Universe is the most interesting thing in this article and the part most people are glossing over. The real question Simon nails is: how do you prove software works when both the implementation and the tests are written by agents? Because agents will absolutely game your test suite - return true, rewrite assertions to match broken output, whatever gets them to green.

Their answer of keeping scenarios external to the codebase like a holdout set is smart. And building full behavioral clones of services like Okta, Jira, Slack so you can run thousands of end to end scenarios without hitting rate limits or production - that's where the actual hard engineering work is. Not the code generation, the validation infrastructure.

Most teams trying this will skip that part because it's expensive and unglamorous. They'll let agents write code and tests together and wonder why things break in production. The "factory" part isn't the agents writing code. It's having robust enough external proof that the code does what it's supposed to.