May I thank whoever is behind HelloSign and HelloFax for making a really, really annoying problem go away. Signing and especially faxing are relics of an old age and thanks to these wonderful people I don't need to find a fax/scanner, especially when travelling.
Dev at HS, here. For our launch we prioritized the top SDKs our community requested. Those SDKs were Java, Ruby, PHP and Python. We know there are a lot of requests for a NodeJS SDK and are looking into how it will fit into a future release. We don't have an official date, but additional sdks (and node.js, in particular) are on the top of our minds.
Ed from BD @HelloSign here. Essentially any process that involves signing a legally binding document is a valid use case because our API makes the process that much simpler. The main ones we see are anyone that needs to send a lot of forms, HR (onboarding, PTO, admin forms), Legal and Real Estate. We've also seen teachers use us for permission slips, gyms for waivers, agencies for releases, etc.