Announcing circle: a Haskell client for Circle's REST API

I’m stoked to announce the initial release of circle, an unofficial but feature-complete Haskell client for Circle’s REST API. This library (and usage guide) is available on Github and on Hackage.

circle supports calling all of the V1 endpoints enumerated in the Circle documentation, and it will support all Circle’s V1.1 features in the next release (Circle launched their V1.1 API as I was finishing this project, lol). This project is experimental, please download it and try it out if you’re curious, and feel free to reach out to me via email or via the Github issues if you spot anything amiss :)


You’ll need to set the environment variable CIRCLE_API_KEY (or something like that) to connect to Circle’s sandbox (or production) environments. Get your keys here.

import Circle.Client
import Circle.Types
import Network.HTTP.Client (newManager)
import Network.HTTP.Client.TLS (tlsManagerSettings)
main :: IO ()
main = do
  manager <- newManager tlsManagerSettings
  config <- sandboxEnvConfig "CIRCLE_API_KEY"
  result <- circle config manager getConfigurationInfo
  case result of
    Right CircleResponseBody b -> print bs
    Left CircleError e -> print e

More documentation on how to use this library can be found on Github


At my old job, we considered building a crypto off-ramp for our customers to convert USDC to Fiat currency, and one of the stablecoin APIs we considered for this integration was Circle. Their REST API documentation was great, but integrating with it would require writing our own library to call it, since there weren’t any existing open-source libraries for Circle’s API that were written in Haskell (a classic conundrum in the Haskell ecosystem). Around that time, I got the idea that such a library could be written and open-sourced and hopefully be useful to folks beyond my coworkers.

Then, after all that, the crypto off-ramp project was shelved, other priorities took over, and I never ended up getting the chance to work on this API client. However, now that I’ve had more time on my hands during this little career sabbatical, one of the things I wanted to do during this time off was to make this vision a reality. I know API clients aren’t the most “hard-core” of engineering projects, but building this was a lot of fun, and I hope future Haskell users find it useful.


I wanted to shout out a few people that were instrumental in me getting this project done (some of whom probably didn’t even know it).

First off, I was heavily inspired by the following libraries with respect to how they implemented their API clients, and I used a similar design for mine:

Next, I wanted to shout out janus from for recommending that I try using autodocodec for writing my JSON serialization instances (and I also want to thank NorfairKing for writing that library!)

Lastly, I wanted to shout out (another old coworker) Vaibhav Sagar for giving me a hand uploading this package to Hackage.