OpenAPI Workbench

View, validate & generate code from OpenAPI documents — in your browser

Specification

OpenAPI 3.0.3YAMLNo issues

    The document passes basic structural validation.

users

get/usersList users

Returns a paged list of users.

https://api.example.com/v2

https://api.example.com/v2/users

Parameters (3)

querylimit
queryoffset
headerX-Request-Trace

Responses

OpenAPI Viewer & Workbench

DataFormatter OpenAPI Workbench is a free, browser-based tool that parses an OpenAPI 3.0/3.1 JSON or YAML document, lists every endpoint and component schema, validates the structure, and generates cURL, fetch, Axios and typed code — with no signup and no upload.

About this tool

What is it?
DataFormatter OpenAPI Viewer & Workbench is a free online tool that parses an OpenAPI 3.0/3.1 JSON or YAML document in your browser, lets you explore every endpoint and schema, validates the structure and generates cURL, fetch, Axios and TypeScript code.
Who is it for?
Developers and API designers who need to understand a documented API quickly, spot structural problems in a spec or get runnable request code without installing a client.
What makes DataFormatter's tool different?
It accepts real-world YAML (block scalars, anchors), resolves $ref safely against circular schemas, and processes everything locally with no upload — including generated code that never carries authorization secrets.

OpenAPI 3.0 vs OpenAPI 3.1

OpenAPI
OpenAPI is a vendor-neutral, machine-readable format for describing HTTP APIs. A single JSON or YAML document lists every endpoint, operation, parameter, request body and response schema, so tools can generate docs, mock servers and client code from it.
OpenAPI 3.0
The 3.0.x line (3.0.0–3.0.4) is the most widely deployed OpenAPI version. It describes operations, servers and components, types nullable values with a separate nullable keyword and bounds with exclusiveMinimum/exclusiveMaximum booleans — the format most published specs use today.
OpenAPI 3.1
The 3.1.x line stays OpenAPI 3 but aligns validation with JSON Schema 2020-12: type: ["string", "null"] replaces nullable, minimum bounds become plain numbers, and a top-level webhooks field is added. DataFormatter's workbench accepts both 3.0.x and 3.1.x in JSON or YAML.

How the OpenAPI workbench helps

Working from a spec file is much faster when you can explore it without reading raw YAML. Load a document and the workbench reduces it to the pieces you actually need: every operation on its tagged endpoint list, every component schema in a searchable list, and a details view for the current endpoint.

  • Endpoint explorer — browse operations by tag with search, then see parameters, request bodies, servers and response codes for each one.
  • Schema explorer — list all components.schemas definitions with searchable property tables that resolve $ref links safely, even in circular schemas.
  • Validation — structural checks report missing response descriptions, duplicate operationIds, unresolved refs and unknown schema types as errors and warnings.
  • Request code generation — one click from cURL to fetch, Axios, Python, Java, Go or C#, honouring path, query and header parameters and JSON bodies.
  • Type generation — turns request and response schemas into TypeScript, Java, C#, Go, Python, Kotlin, Swift or Dart declarations by reusing the JSON to Code engine.
  • Mock responses — every response status gets a clearly-labelled placeholder body generated from its schema, never presented as real API output.

Security details at a glance

Each endpoint reports the authentication it declares — API keys, HTTP Bearer tokens, OAuth 2.0 or OpenID Connect — with the scopes it requests. Generated snippets deliberately omit your credentials so nothing secret is ever copied or exported. As with the other DataFormatter tools, all processing happens locally and documents are never uploaded.

Reading a new API quickly

Upload the spec the team keeps in the repo and jump straight to the operations and schemas you are about to integrate with.

Checking a spec before sharing

Run validation before a pull request — missing response descriptions, duplicate operationIds and dangling $refs are surfaced with their location.

Copying runnable request code

Pick an endpoint, adjust path and query values in the parameter rows, and copy a ready request in the language your client is written in.

Frequently asked questions

Is DataFormatter's OpenAPI workbench free and does it need a signup?

Yes, it is completely free with no account or signup. Paste JSON or YAML, or upload a spec file, and every feature works instantly in the browser.

Does the OpenAPI workbench upload my API specification to a server?

No. Parsing, validation, schema exploration and code generation all run locally in your tab. The document you paste or upload never leaves your machine.

Which OpenAPI versions are supported?

The workbench accepts OpenAPI 3.0.x and 3.1.x documents in JSON or YAML, including real-world YAML with block scalars and anchors. Swagger 2.0 documents are detected and reported as unsupported rather than misinterpreted.

What code does the OpenAPI workbench generate?

For any endpoint it produces cURL commands plus JavaScript fetch, Axios, Python requests, Java, Go and C# snippets, and it converts request or response schemas into TypeScript interfaces, Java classes, C# records, Go structs, Python dataclasses, Kotlin and Swift.

Related tools

Last reviewed September 2026 · DataFormatter team — this tool processes data locally in your browser.