OpenAPI Editor & Viewer
Paste your OpenAPI/Swagger spec to edit, validate, and preview endpoints and schemas instantly.
About This Tool
The OpenAPI Editor & Viewer is a free browser-based tool for editing and visualizing OpenAPI (formerly Swagger) specification documents. Whether you are designing a new REST API or reviewing an existing one, this tool gives you a live preview of your endpoints, request parameters, response codes, and data schemas side by side with your YAML or JSON source.
All processing happens entirely in your browser. Your API specifications never leave your machine — there are no server round-trips, no logging, and no third-party analytics on your input. This makes it safe for internal API designs, proprietary schemas, and specifications that reference private infrastructure.
The editor supports both YAML and JSON input modes. You can
toggle between them depending on your preference. The live
preview panel renders endpoints with color-coded HTTP method
badges (GET in green, POST in blue, PUT in orange, DELETE in
red), expandable parameter tables, request body references, and
response status codes. Schemas from the components/schemas
section are displayed as expandable cards showing each field's
name, type, format, and whether it is required.
If you work with related data formats, you may also find the YAML Formatter useful for cleaning up your YAML before pasting it here, or the JSON Schema Generator for creating schemas from sample JSON payloads. For converting between JSON and YAML, try the JSON to YAML Converter.
Three sample specifications are included — Petstore, Todo API, and User Management API — so you can explore the tool immediately without writing any YAML. The Copy and Download buttons let you export your edited spec in a single click.
How to Use
- Select the input mode (YAML or JSON) using the toggle buttons at the top.
- Paste your OpenAPI specification into the left editor panel, or click one of the Sample badges (Petstore, Todo API, User API) to load a demo spec.
- The Live Preview panel on the right instantly renders your API info, endpoints, and schemas.
- Click any endpoint row to expand it and see parameters, request body, and response details.
- Click any schema card to expand it and inspect individual fields, types, and required markers.
- Use the Copy button or press Ctrl+Shift+C to copy the spec to your clipboard.
- Click Download to save the spec as a
.yamlor.jsonfile. - Click Clear to reset both the editor and preview panels.
Popular OpenAPI Editor Examples
FAQ
Is my data safe when using this tool?
Yes. All parsing and rendering is performed client-side in your browser using JavaScript. No data is transmitted to any server. You can safely edit API specifications that contain internal endpoints, authentication details, or proprietary schemas.
Which OpenAPI versions are supported?
The editor works with OpenAPI 3.0.x and 3.1.x specifications. It parses standard structures including info, servers, paths, components/schemas, and securitySchemes. Swagger 2.0 files will parse partially but may not render all features correctly.
Can I switch between YAML and JSON input?
Yes. Use the YAML/JSON toggle buttons at the top of the editor. When you switch modes, you need to paste or write input in the selected format. The preview panel works identically regardless of input format.
What do the colored method badges mean?
Each HTTP method is color-coded for quick identification: GET is green, POST is blue, PUT is orange, PATCH is yellow, and DELETE is red. This follows common API documentation conventions used by tools like Swagger UI and Redoc.
Does the editor validate my OpenAPI spec?
The editor validates the YAML or JSON syntax and checks for basic OpenAPI structure (info, paths, components). It will show syntax errors with line numbers. However, it does not perform full OpenAPI specification validation (e.g., checking that all $ref references resolve correctly).
Can I use this for internal or private APIs?
Absolutely. Since everything runs in your browser with zero server communication, this is ideal for editing internal API specs that should not be uploaded to third-party services. No data leaves your machine at any point.
How do I export my edited specification?
Click the Download button to save the spec as a file (openapi-spec.yaml or openapi-spec.json depending on your input mode). You can also click Copy or press Ctrl+Shift+C to copy the entire spec to your clipboard for pasting into your project.
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