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Yahoo! Developer Network - Frequently Asked Questions

Here is a list of the questions we get asked most frequently, with their answers. If you don't find an answer to your question, please contact us.

Yahoo! Web Services and APIs

Q: What are Yahoo! Web Services and APIs?

Web Services provide application developers access to content and services to build new applications. For example, you can combine our data and services with those you create in a desktop application or those offered by other Web sites. With Yahoo! Web Services, more of the power of the Yahoo! network is in your hands.

Q. Who are Yahoo! Web Services and APIs for?

Yahoo! Web Services are for developers, businesses, and researchers interested in using Yahoo! products, services, data, and content as a resource in their applications. Currently, this program is free, not subject to any SLA or uptime agreement, and subject to daily limits on query volume. If your requirements are above and beyond our standard non-commercial usage policies, please contact us and tell us how we can help your business grow.

Q: What do I need to access Yahoo! APIs?

To access Yahoo! Web Services, we require that you register and use an API Key (sometimes referred to as application ID), which is tied to your application. Your application ID must be sent with each Web Services request. Your application must also follow our Usage Policy.

Q: What is an Application ID?

As noted in the preceding answer, an Application ID is a string that uniquely identifies your application. Think of it like a User-Agent string. If you have multiple applications, you must use a different ID for each one. Get yours here.

Q: What is REST?

REST stands for Representational State Transfer. Most of the Yahoo! Web Services use "REST-Like" RPC-style operations over HTTP GET or POST requests with parameters URL encoded into the request.

For more information about REST, you can start with the following:

Q: What programming languages does Yahoo! support?

You can use any language you like. Our SDK provides libraries and/or examples in various languages.

Q: Where can I get help on using Yahoo! Web Services and APIs? Where do I report bugs or outages?

The best way to report bugs, outages, or unexpected behavior is by posting to the developer support forum for the Web Service or API in question.

Limitations and Commercial Use

Q: What are the guidelines and limitations for applications using Yahoo! Web Services and APIs?

All of our Web Services are available for use up to the standard per-service rate limit in applications and Web sites that comply with our Terms of Use. Many of our Web Services will allow certain kinds of business usage, but this can vary per-service. You can review our general Usage Policies for more information about what is permitted.

Q: Does it cost anything to use Yahoo! Web Services and APIs?

No. We do not charge for access to our Web Services. We make them available for free to you as-is, rate limited, and controlled by the relevant Terms of Use. We will be providing more commercial terms going forward. You may use the services up to their individual standard daily rate limit (see the documentation for specifics) in applications that comply with our Usage Policies.

Q: What are the limits on how much I can use Yahoo! Web Services?

Access is rate-limited based on the caller's IP address, and queries are limited per IP and per day. Each service may have a different access rate limit. See the documentation for each service for more information. Circumvention of these rate limits by any means is expressly forbidden under our Terms of Use .

Q: How will I know when I hit the daily limit?

When a rate limit has been exceeded, the HTTP request will receive an error code of 403, along with a standard XML error response. See our rate limiting documentation for details.

Q: How do I request additional queries?

You can request additional queries for your application via this form. However, not all requests can be approved at this time.

Q: What is the limit on the number of results I can receive per query?

Each service may have different limits on the number of results returned by each query, as well as other variations in supported parameters. The documentation for each service specifies the default number and maximum number you can receive.

Q: Some of your services say "non-commercial use only." What does that mean?

Some of our services are made available only for use in non-commercial applications. For those services, we are not able to place firm limits on what we consider "commercial use" because so many unforeseen uses are invented daily that we need to maintain a level of flexibility — especially while the program is free. That said, the following general examples show uses we consider to be commercial:

  • Use of our services on high traffic, established commercial-oriented or business web sites or applications
  • Applications or web sites monetized indirectly (by advertising, affiliate links) or directly, including subscriber-only content (subscriptions, software-as-a-service, hosted applications where your users pay for access) and for-pay applications, products, or services
  • Productivity tools for businesses created to bring value to a business function, typically only accessible to select users

Developers can create applications that use our APIs and web services as work-for-hire for clients; however, the usage within the application itself must be approved.

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