Ask HN: API or service to connect, read and publish to major social networks?

I'm about to embark on a project to create a social media management portal for a client. It requires integrations with about 15 most popular social networks. And for each of them, we would need OAuth support, being able to read comments, posts and messages, being able to respond to posts, comments and messages, and publish posts.

I would really really like to avoid maintaining these APIs myself and was hoping there’d be a reliable third-party service that I could use.

Here’re some of the networks we’re looking to connect to:

- [ ] LinkedIn - [ ] Reddit - [ ] Google+ - [ ] Twitter - [ ] Facebook - [ ] Pinterest - [ ] Tumblr - [ ] Instagram - [ ] YouTube - [ ] FourSquare

Does anyone know of an API or service we could use here?