Auto-generate an OpenAPI spec by listening to localhost
Hey HN! We've developed OpenAPI AutoSpec, a tool for automatically generating OpenAPI specifications from localhost network traffic. It’s designed to simplify the creation of API documentation by just using your website or service, especially useful when you're pressed for time. Documenting endpoints one by one sucks. This project originated from us needing it at our past jobs when building 3rd-party integrations. It acts as a local server proxy that listens to your application’s HTTP traffic and automatically translates this into OpenAPI 3.0 specs, documenting endpoints, requests, and…
In plain words
OpenAPI AutoSpec is a development tool that automatically generates OpenAPI 3.0 specifications by monitoring HTTP traffic on localhost. It works as a local server proxy that captures requests and responses from running applications, then translates them into complete API documentation without manual endpoint entry. Designed for developers building integrations or needing quick API docs, it installs via NPM and requires only basic command-line arguments to specify input and output locations.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
Hey HN! We've developed OpenAPI AutoSpec, a tool for automatically generating OpenAPI specifications from localhost network traffic. It’s designed to simplify the creation of API documentation by just using your website or service, especially useful when you're pressed for time. Documenting endpoints one by one sucks. This project originated from us needing it at our past jobs when building 3rd-party integrations. It acts as a local server proxy that listens to your application’s HTTP traffic and automatically translates this into OpenAPI 3.0 specs, documenting endpoints, requests, and responses without much effort. Installation is straightforward with NPM, and starting the server only requires a few command-line arguments to specify how and where you want your documentation generated ex. npx autospec --portTo PORT --portFrom PORT --filePath openapi.json It's designed to work with any local website or application setup without extensive setup or interference with your existing code, making it flexible for different frameworks. We tried capturing network traffic on Chrome extension and it didn't help us catch the full picture of backend and frontend interactions. We aim in future updates to introduce features like HTTPS and OpenAPI 3.1 specification support. For more details and to get started, visit our GitHub page (https://github.com/Adawg4/openapi-autospec). We also have a Discord community (https://discord.com/invite/CRnxg7uduH) for support and discussions around using OpenAPI AutoSpec effectively. We're excited to hear what you all think!
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