CmisSync vs mailboxlayer API

Synchronize documents between your computer and your enterprise file server (Alfresco, SharePoint, Documentum, any CMIS-compliant server)

It is like Dropbox for Enterprise Content Management!
For file sharing/synchronization, don't get a new server or rely on the cloud: just use your existing document management server.
Free and open source.

Free & Simple Email Verification JSON API

Mailboxlayer is a free, simple and powerful JSON API offering instant email address validation & verification via syntax checks, typo and spelling checks, SMTP checks, free and disposable provider filtering, and much more. Its system is REST-based, secured by 256-bit HTTPS encryption, and pursuing the goal of assisting developers and businesses in fighting fraudulent users and increasing success rates of email campaigns.