Sometimes people wonder why we bother building APIs since it seems they can end up being used in ways that compete with our own products.
There are idealistic reasons for building APIs, as outlined by Jonathan Rosenberg, but there are also commercial benefits even if you don't share that philosophy. The main one is that APIs reduce the friction involved in making your services more valuable. They make it easier for other people to add data to your services.
They also attract more users to your services by effectively advertising them on other people's sites. As well as increasing your visibility APIs also ensure that users are more likely to try your services since the risk of lock-in is reduced. If you have at least a CRUD API potential users know that there will be a mechanism for extracting their data if something better comes along or if your services change in ways they don't like.
The other benefit of APIs is that they lower the cost of experimentation and increase the set of potential experimenters. These experiments can serve your users in two ways. Firstly they can handle niche use cases without cluttering the user interface of the application. Secondly some of these niche use cases may turn out, after a period of refinement, to be useful for mainstream users or for attracting completely new sets of users.
Another thing we've learned the hard way is that if you don't give people an API or you give them an insufficient API they'll resort to screen-scraping and hacking in order to unlock the value in your product. This can create dependencies on things that were never meant to be stable or it can lead to the emergence of widely-used but unofficial APIs.
That behaviour can harm your product, your developers and your users. For example it can lead to a mismatch in expectations when some developers believe they're using an official API with established deprecation and change management policies. You also have to ensure that the APIs you create don't damage the product, for instance, by making it very easy to spam or game your system.
Providing an API, no matter how good, is just the start. The next challenge is to make something valuable enough that developers will use it in the absence of some extrinsic compulsion.
Firstly this involves making something that's easy to experiment with. So it should be easy to copy-paste a personalised URL into a browser and see a pretty-printed dataset.
Then you have to offer a path from there. The path starts with letting people play even if they don't understand your service all the way to the point where they understand your abstractions and the specifications you're using.
People should be able to go from playing in the browser to playing at a terminal with curl/wget to playing with an OAuth-enabled HTTP client to playing with your specialized wrapper libraries for your API to building businesses upon your platform.
But you can't just stop there. If you want to go from merely offering an API (typically a set of CRUD operations on your product's datasets) to building a viable platform you need to solve some difficult problems:
- how does your platform, as opposed to your product, generate revenue or value for you?
- how does your platform generate revenue or value for those who build upon it?
- how do you respond to and/or incorporate the innovations that will be built upon your platform?
- how do you nudge developers into creating more value than they capture from your users and your platform?
- what happens to this surplus value? Is it being re-invested in the platform or siphoned off?
Even if you solve all these problems you don't have any guarantees of long-term success. The transition from API to platform to ecosystem is difficult and most APIs don't make it. However APIs can still help developers create new possibilities along the way.