Podio is a Web Service that aims to provide a customizable online workplace. There are a lot of apps, and you can set up and position your dashboard as you please. However, sometimes the app you want isn't in the set. In that case, they also offer the Podio API to code your own custom apps for use within your Podio workspace.
From the API reference:
What is the Podio API?
The Podio API is a complete programmable interface to all Podio functionality. We currently provide wrappers for Ruby, Java, PHP and Python which make working with common API operations very simple.
What can you do with it?
Quite a lot! In fact, the entire Podio frontend is built on the API, and we've exposed it all for you to use too. If you want to build event-driven applications, you have the ability to register Webhooks in your Podio apps. There are some sensible rate-limits in place, but if you need us to raise them for your app, get in touch.
The API is RESTful, utilizing OAuth2 for Authentication, and with responses formatted in JSON. Podio has done a lot of work to make it easy to use, even for people who aren't normally coders. It does require an API key. The tutorials section of the Documentation is a welcome piece, helping you dive right in and get things done.
Podio held a hackathon in May and the winner shared his insights into the Podio platform:
Many technical entities develop an API as an afterthought and the reliability and consideration (or lack thereof) shows. Podio bravely (!) decided to re-implement their web interface as a client of their own API. This is a brave move, but by testing whether they themselves could work with the API they were providing, they wound up creating a better, more-intuitive app.
There's also a nice Podio presentation from SlideShare (embedded above).