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Your spec never leaves your browser

Unlike other API tools (Postman, SwaggerHub, Stoplight) that sync your specifications to their cloud servers, LangStop OpenAPI Editor runs entirely in your browser. There is no backend, no data collection, and no telemetry. Open DevTools → Network tab to verify — zero requests, every time.

Frequently Asked Questions

What is an OpenAPI Editor?
An OpenAPI Editor lets you design, edit, and validate OpenAPI 3.x specification files in YAML or JSON format with a live preview of your API documentation — all in your browser, with no installation needed.
Is my OpenAPI spec data uploaded to any server?
No. All processing happens 100% in your browser via a Web Worker. Your specification never leaves your computer. You can verify this by opening your browser's DevTools → Network tab while editing — you'll see zero outbound requests.
How do I verify my data stays private?
Open your browser's DevTools (F12), go to the Network tab, and start editing. You will see zero requests to external servers. The editor uses a Web Worker running entirely in your browser's memory.
Can I import an existing OpenAPI spec?
Yes. You can import specs by pasting a URL (raw GitHub URLs work great), uploading a .yaml/.json file, pasting YAML/JSON text directly, or starting from a built-in template like Petstore 3.0 or the empty scaffold.
Do I need an account to use this?
No. There is no signup, no login, no account. The editor is completely free and works instantly.
What OpenAPI versions are supported?
OpenAPI 3.0.x (3.0.0 through 3.0.3) and 3.1.x (3.1.0+) with real-time validation. The editor supports both YAML and JSON formats, including OAS 3.1 features like webhooks and JSON Schema 2020-12.
Can I share my spec with others?
Yes — click the Share button in the toolbar to generate a unique link with your spec embedded (compressed in the URL). Anyone with the link sees a read-only preview. No data is uploaded to any server.
Does the editor work offline?
Yes. After the first load, the editor caches all assets. The spec validation runs in a local Web Worker. Your specs are persisted in your browser's localStorage.

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