APIs.guru Getting Started: Explore OpenAPI Directory (2026)

Getting started overview

APIs.guru provides a comprehensive, community-curated directory of OpenAPI specifications for various public APIs. Unlike platforms that offer direct API access or a unified SDK, APIs.guru functions as a repository of API definitions. This means your 'getting started' process focuses on discovering relevant APIs, understanding their specifications, and then using those specifications to interact with the chosen API directly, often through a client library generator or a direct HTTP client.

The core value of APIs.guru lies in its collection of machine-readable API definitions, primarily in the OpenAPI Specification format. These specifications detail an API's endpoints, operations, parameters, authentication methods, and response structures. By providing these definitions, APIs.guru enables developers to:

• Discover APIs: Browse a wide range of public APIs across different categories.
• Understand API Capabilities: Review detailed API documentation generated from the OpenAPI specification.
• Generate Client Libraries: Use tools like Swagger Codegen or OpenAPI Generator to create SDKs in various programming languages directly from the specification.
• Automate API Interactions: Integrate API calls into workflows using the structured information provided by the OpenAPI definition.

This guide will walk you through finding an API on APIs.guru, obtaining its OpenAPI specification, and making a sample request using a common HTTP client like curl, which can be informed by the specification.

Create an account and get keys

APIs.guru itself does not require an account or API keys because it is a directory of OpenAPI specifications, not an API provider. All the OpenAPI definitions are freely accessible and can be browsed or downloaded directly from the APIs.guru OpenAPI Directory. You do not need to sign up, log in, or generate any credentials to use APIs.guru's services.

However, the individual APIs listed within the APIs.guru directory often require their own accounts and API keys for access. When you select an API from the directory, you will typically need to visit that specific API provider's website to:

1. Sign up for an account: Register with the API provider (e.g., Stripe, Twilio, Google Cloud).
2. Obtain API credentials: Generate API keys, tokens, or other authentication details specific to that provider. These credentials are what you will use to authenticate your requests against the third-party API.
3. Review API-specific documentation: Consult the provider's official documentation for details on their authentication mechanisms, rate limits, and specific usage policies.

For example, if you find the Stripe API specification on APIs.guru, you would then go to the Stripe website to create an account and obtain your Stripe API keys. These keys would then be used when making requests to the actual Stripe API endpoints, not to APIs.guru.

Your first request

To make your first request, you'll first need to select an API from the APIs.guru directory and obtain its OpenAPI specification. For this example, we'll use a simple, publicly available API that doesn't strictly require authentication for basic requests, if one is available and suitable within the directory for demonstration purposes. If not, we will proceed with the general steps, noting where API-specific authentication would be inserted.

Step 1: Browse and select an API

1. Navigate to the APIs.guru OpenAPI Directory.
2. Browse the list of APIs or use the search functionality to find an API of interest. For this example, let's consider an API like the Esri ArcGIS Geocoding API, as it is often listed and has publicly accessible endpoints for basic queries.
3. Click on the API entry to view its details and access its OpenAPI specification. You'll typically find a link to the raw JSON or YAML file.
4. Download the OpenAPI specification file (e.g., arcgis.com.arcgis-geocoding.json).

Step 2: Understand the API endpoint from the specification

Open the downloaded OpenAPI specification file in a text editor. Look for the servers array to identify the base URL and the paths object to find available endpoints and their methods (GET, POST, etc.).

For the ArcGIS Geocoding API, you might find a base URL like https://geocode.arcgis.com/arcgis/rest/services/World/GeocodeServer/ and a path like /findAddressCandidates for address geocoding.

An example path might look like this in the spec (simplified):

{
  "paths": {
    "/findAddressCandidates": {
      "get": {
        "summary": "Find Address Candidates",
        "parameters": [
          {
            "name": "address",
            "in": "query",
            "description": "The address to be geocoded.",
            "required": true,
            "schema": {
              "type": "string"
            }
          },
          {
            "name": "f",
            "in": "query",
            "description": "The response format (json, pjson).",
            "required": true,
            "schema": {
              "type": "string",
              "enum": ["json", "pjson"]
            }
          }
        ],
        "responses": {
          "200": {
            "description": "Successful response with geocoding results."
          }
        }
      }
    }
  }
}

From this, we can deduce that a GET request to /findAddressCandidates with address and f query parameters is expected.

Step 3: Construct and execute your first request

Using curl, you can construct a request based on the information from the OpenAPI specification and the API's base URL.

Example request for the ArcGIS Geocoding API to find candidates for an address:

curl -X GET \
  "https://geocode.arcgis.com/arcgis/rest/services/World/GeocodeServer/findAddressCandidates?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA&f=json" 

This command sends a GET request to the specified endpoint with the address query parameter and requests a JSON format response. The output will be the JSON response from the ArcGIS Geocoding API, containing potential address candidates.

Common next steps

After successfully making your first request using an API's OpenAPI specification from APIs.guru, several common next steps can enhance your API integration workflow:

1. Generate a Client Library: Instead of manually crafting curl commands, use tools like OpenAPI Generator or Swagger Codegen to automatically generate an API client in your preferred programming language (e.g., Python, Java, JavaScript). This provides a ready-to-use SDK that handles HTTP requests, serialization, and deserialization, significantly speeding up development.

   
       # Example using OpenAPI Generator CLI
       openapi-generator generate -i your-api-spec.json -g python -o ./my_python_client
       

2. Explore Advanced Endpoints: Review the OpenAPI specification for other available endpoints, operations (POST, PUT, DELETE), and more complex data models. Understand how to interact with resources, send data in request bodies, and handle different response types.
3. Implement Authentication: For most production APIs, you will need to implement proper authentication. The OpenAPI specification will describe the authentication schemes (e.g., API Key, OAuth2, HTTP Basic). Refer to the target API provider's documentation for specific implementation details on how to use your API keys or tokens securely. For instance, OAuth 2.0 is a common framework for delegated authorization.
4. Error Handling and Rate Limits: Integrate error handling into your code to gracefully manage API responses indicating failures (e.g., HTTP 4xx or 5xx status codes). Also, be aware of and implement strategies for handling rate limits imposed by the API provider to avoid getting blocked. The OpenAPI specification might hint at common error responses, but the API provider's documentation is the definitive source.
5. Integrate into an Application: Incorporate the generated client library or direct API calls into your application's codebase. This involves managing API credentials securely (e.g., using environment variables or a secrets manager), structuring your code for maintainability, and testing your integration thoroughly.
6. Stay Updated: APIs can evolve. Periodically check the APIs.guru directory or the API provider's official channels for updated OpenAPI specifications. Regenerate your client libraries if significant changes occur to ensure compatibility.

Troubleshooting the first call

When making your first API call using an OpenAPI specification from APIs.guru, you might encounter issues. Here's a guide to common problems and their solutions:

• Incorrect Endpoint or Method:
  • Problem: Receiving 404 Not Found or 405 Method Not Allowed errors.
  • Solution: Double-check the OpenAPI specification for the exact path and HTTP method (GET, POST, PUT, DELETE) for the endpoint you are trying to reach. Ensure the base URL is correct.
• Missing or Incorrect Parameters:
  • Problem: Receiving 400 Bad Request errors or unexpected responses.
  • Solution: Verify that all required parameters (as marked in the OpenAPI spec) are included in your request. Check parameter names, data types, and formats. For query parameters, ensure they are correctly URL-encoded.
• Authentication Issues:
  • Problem: Receiving 401 Unauthorized or 403 Forbidden errors.
  • Solution: This is a common issue. APIs.guru does not provide API keys; you must obtain them from the target API provider. Ensure you have valid credentials (API key, token, OAuth access token) and that they are included in the request according to the API's authentication scheme (e.g., in headers, as a query parameter). Consult the target API's official documentation for precise authentication instructions, for example, AWS Security Credentials or Google OAuth 2.0.
• Network Connectivity:
  • Problem: Request timeouts or connection refused errors.
  • Solution: Check your internet connection. Ensure there are no firewalls or proxy settings blocking your outbound requests. Try accessing the API's base URL directly in a web browser to confirm it's reachable.
• JSON/XML Formatting Errors:
  • Problem: Receiving 400 Bad Request when sending a request body (e.g., for POST/PUT requests).
  • Solution: Ensure your request body (JSON, XML) is correctly formatted and matches the schema defined in the OpenAPI specification. Check content-type headers (e.g., Content-Type: application/json).
• Rate Limiting:
  • Problem: Receiving 429 Too Many Requests errors.
  • Solution: You've sent too many requests in a short period. Wait for the rate limit to reset (often indicated by Retry-After headers) or space out your requests.
• Outdated OpenAPI Specification:
  • Problem: The API behaves differently from what the specification describes.
  • Solution: While APIs.guru strives for up-to-date specifications, APIs can change. Always cross-reference with the target API provider's official documentation if you suspect discrepancies.

When troubleshooting, always refer to the specific error messages returned by the API. They often provide valuable clues about what went wrong. Additionally, tools like Postman or Insomnia can help visually construct and test API requests, simplifying the debugging process.