Building Stripe's API | Hacker News Reader

Building Stripe's API

amberonrails.com

138 pointsboucher17 comments

This is a great post. I'm currently building an API that's really inspired by Stripe's API. I'm trying to mimic a lot of these elements, from the easy authentication through to the really useful error messages.

One of the things I'm not so sure about is the local bindings for each language. I'm tempted to just use off-the-shelf HTTP clients or a very thin wrapper in each language and write code snippets based on them. I'm not sure I see the value in writing full client bindings - I've often found it harder to use in many cases when I use these 'opinionated' bindings in the past. You often end up with a choice of entirely following the libraries views on error handling or digging around and breaking upgrades by modifying these libraries directly. I've always preferred much thinner wrappers that have no knowledge of the underlying API calls. Would love more opinions!

(I work at Stripe.)

As an API author, I think your goal should be to make interacting with your API as simple and robust as possible. The downside with just recommending off-the-shelf HTTP clients is that there's always a ton of logic (whether request formatting, error handling, or turning responses into first-class objects) that the vast majority of consumers of your API want and will have to write on their own. If you look at the internals of our bindings, a lot of the logic is around understanding exceptions (https://github.com/stripe/stripe-ruby/blob/master/lib/stripe...) or interstanding semantics of our API (https://github.com/stripe/stripe-ruby/blob/master/lib/stripe...), which are tasks that would take a newcomer a lot of time to get get spun up on.

There will always be frameworks where your bindings don't work (e.g. our Ruby bindings aren't compatible with EventMachine) or paradigms that they violate (e.g. using error return values in PHP rather than throwing exceptions). That's actually ok -- just because you can't support everyone doesn't mean you should support no one. Instead, we put a lot of effort into making our bindings compatible with as broad of a range of environments as possible (e.g. https://github.com/stripe/stripe-python/blob/master/stripe/_...).

So my advice would be write bindings which convert the semantics of your API to the consumer's language, but which constrain the consumer's application as little as they can. Even if people end up having to use a lower-level abstraction to talk to your API, they can probably steal code or ideas from what you've written.

That's great advice, thanks! Hadn't thought about how it improves the ability of the vast majority of developers to get up to speed with handling edge cases. That's a really good point. Perhaps I'll start with thin wrappers and progressively add deeper bindings to get the best of both worlds.

Writing bindings makes sense if people are paying you to consume your API (AWS, Stripe, Twilio, etc) - it makes it easier for people to pay you money. If not the decision gets a little murkier.

I wrote a lot along similar lines here:

http://kev.inburke.com/kevin/client-library-design/

I personally think API design should be done by someone who has background in both UX and engineering. Even though you know your audience is going to technical, you'll eventually have people across the spectrum from noobs to pros using your APIs.

I completly agree. We often forget that an API is still an interface, and it is often more a designer and part that a technical part.(but still a technical part or maybe a cultural technical part) In Real Life, product interface design or service interface design is often better made by external desiner that focus on understanding OBJECTIVELY how users will and want interact with , than the original producer or provider which will be affected by what he wants to expose and its history and vision about his product.

I disagree. As a programmer every function signature you write is an interface to the code inside. API design is a slightly higher-level version of this. I would expect good engineers to be able to design good API's, it's a natural extension of something they should be good at anyway.

Engineering and UX design are both examples of communication. When I write code I communicate with multiple audiences in mind - the compiler, my current and future colleagues, and future versions of me, that might not remember what this variable is, so better name it meaningfully. Similarly I communicate with my employers about what they want me to develop, and I communicate with our users, to help them understand what this thing that I coded does, and how that is beneficial to them.

I find that the best engineers (indeed the best people in any role) are the best communicators, who are constantly aware of the many audiences that they are communicating with and are always weighing these many different needs. A good engineer is an ambassador between the technical and non-technical.

I think interface designer should be the person who understand the use case of it's users.

On a related note, I think the design and organization of your API's documentation is equally as important as the design of the API itself. Stripe's mostly single-page two-column layout (found here: https://stripe.com/docs/api) is brilliant, and makes it extremely easy to find what you're looking for.

Great explanatory post. I was wondering if dog-fooding would come up but I guess Stripe is one online service in which dog-fooding -- in terms of providing views of the service content -- would be non-straightforward.

Also, who else thought the domain name referred to a new client-side framework for RoR? :)

Though perhaps not as dog-fooding as some other projects, we do build (almost) all of our dashboard on top of our API. This was one of my first goals at Stripe, and I think it's been a huge win for us. We also have a couple of employees who run a real business with Stripe.

Fantastic post, and it's chock full of great tips!

As someone who was just finished building v1 of a REST API for $work, I wish I had learned some of these lessons 6 months ago. I took a lot of inspiration from Stripe and Twilio but there are so many things I'd do differently for version 2. One advantage I do have is that our API is not consumer facing so I didn't do as much work on the docs and example request/response as I would have otherwise.

My favorite slide was the one showing the details of a particular POST request. I'm not currently logging requests like this, but my eyes have been opened now to the possibilities it brings. Just the ability to debug a response alone would make it worth it. No more tailing apache and backend logs!

We looked at Stripe as a source of inspiration when we were rebuilding our API: http://developers.box.com/docs/

I've always wondered how this was implemented:

> We keep a per-user version which reflects the state of the API the first time the user made an API request

As someone who's just adding stripe to a rails app now, I <3 Stripe.

I think this is a mis-leading title. It should be "Building With Stripe's API". Unless I missed it, I didn't see any behind the scenes stuff about the tech or infrastructure Stripe uses to build out and sustain their API.

Don't think so... the article talks about the driving factors in the decisions made at Stripe when designing the API that should be exposed as the product of the company. The article isn't about how to use Stripe's API to build stuff, it is about why they made the decisions to support and not support the functionality they did.

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