Which free web services are useful as application building blocks?

Question

I used to be a skeptic regarding web services, because I often found the examples given too complex or unconvincing. Stackoverflow, with its use of reCAPTCHA, OpenID, and gravatar, has changed my view. Their use is a showcase of web services that can simplify the deployment of an application by handling part of the required functionality, while also providing more value to the application than what could be achieved by embedding the feature in it.

What other web-service-based application building blocks would you recommend? Ideally, I'm looking for services that are simple to use (RESTful), freely available, reliable, value-adding, and that can be setup with minimal negotiation with their provider.

Answer 1

I think it kind of depend on wich kind of website you are building.

yahoo provides a great number of usefull services. Like if you want to show some financial data on your site.

Answer 2

Google's Chart API is pretty awesome.

Actually Google has a lot of public API's for all kinds of stuff.

• Google API's

Answer 3

"Hi guys, what programming language do you recommend?"

Once you have an idea of what you want to do, your best bet is to spend some time on Programmable Web. They have done a great job of indexing and cataloging various web apis.

Some common building blocks: You want to use RSS or Atom to syndicate data from other sites. You want to use openid or oauth for easy userids and transportable identities. Check out opensocial to make your site easy to interconnect with others.

This is assuming you want to build a site for people to interact with each other and other websites. Once you've narrowed it down from there, Programmable web is a treasure trove of APIs.

Answer 4

eBay provides very well designed and documented API available as web services and RESTful calls. Additionally they have sandbox environment that allows you to play with all APIs with no risk and cost.

Answer 5

I just discovered random.org, a provider of true random numbers. The intereface is documented here. This is a simple get request.