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OpenAPI guide

Browse an OpenAPI spec without uploading it.

Open the openapi.yaml or openapi.json file in Blobster. It recognises OpenAPI 3 documents, lists every operation with its parameters, schemas and responses, and can send a test request to a server you choose. The spec itself is never uploaded. Swagger 2.0 files open as a plain tree.

Published 14 October 2026 4 minute read By Mochavi
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Short answer

Use Blobster for a quick, private index of an OpenAPI 3 spec: find an operation, read its parameters, schemas and responses, and send a test request to your own server. For rendered reference docs, or for Swagger 2.0, build HTML docs on your own machine with Redocly CLI.

Key points

  • Blobster detects OpenAPI 3 from the openapi field in JSON or YAML. Swagger 2.0 files use a swagger field and open as ordinary JSON or YAML.
  • The Preview lists operations and filters them by text, method and tag.
  • Each operation shows its operation ID, tags, parameters, request and response schemas and declared responses.
  • Try request sends a call only when you press Send request, to the server you enter, and opens the response as a document.
  • Shared schemas and parameters under components stay browsable in the tree view.

Steps

  • Open the spec file or drag it into Blobster. In Chrome, a raw spec URL can also open straight into Blobster when auto-open is on.
  • OpenAPI documents get a Preview tab. Type part of a path, an operation ID or a tag to filter, or pick a method or tag from the filters.
  • Select an operation to see its parameters (name, location and whether it is required), its request body media types and its responses.
  • Use Copy path, or Copy URL when the spec declares a server.
  • Switch to Tree for components, examples and anything else the Preview summarises, or to Raw for the exact text.

Send a test request

Under each operation, Try request opens a request form. Blobster fills in the first server URL from the spec, the path and the request body example where the spec defines one. Add path and query parameters, headers and variables, and pick an auth mode: none, bearer token, API key header or API key query.

Send request calls the server you entered and opens the response as a new document, so a JSON response gets the tree, search and copy tools. Back returns to the spec. Requests time out after 30 seconds and responses are limited to 5 MB. Blobster keeps the last eight responses in memory. Request presets you save also stay in memory and are cleared when you switch to another operation.

Copy cURL turns the request into a command. It includes the headers and auth you entered without masking, so treat the copied command like the token in it.

Why keep a spec local

Internal specs describe endpoints that have not been announced, server hostnames, authentication schemes and example payloads. Pasting one into a hosted editor means trusting that site with all of it. Blobster opens the file in the extension and keeps it there.

Limits

Blobster is an index and inspector, not a documentation renderer. It does not lay out schemas as reference pages, and it does not recognise Swagger 2.0.

When you need readable docs to share with a team, redocly build-docs turns a Swagger 2.0, OpenAPI 3.0 or OpenAPI 3.1 description into a standalone HTML file on your machine. Swagger UI is also distributed as static files, an npm package and a Docker image if you prefer its interface.

Sources

Local-first workbench

Inspect the data. Keep the document local.

Open JSON, logs, tokens, configs and tables in Blobster without adding an account, telemetry or a public paste URL.

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