This question has been answered by multiple community members. See the first response.
Its simple site but its made in best CMS.I don't know of any MODX extra that would do all those sites.I was thinking of that but I dont hav ethat much heavy knowledge to convert a bird into an animal.
It might be possible to adapt the Sharedaddy part of Jetpack for use in MODX, but it would be a major job.

Its simple site but its made in best CMS.Does Jetpack post to those services automatically when you publish a post, or does it just send you to their posting page?Hello BOB, you helped me earlier with many problem. Expecting this also. Jetpack has a setting where we can connect our fb, google+, twitter, tumblr and then, when we post the article, it automatically publishes to the connected sites like fb page , twitter.
BTW, the Notify snippet will post to Twitter and Facebook (via a #fb Twitter tag), and optionally send emails to subscribers, but it's not automatic. You have to click on a button to do it.
Its simple site but its made in best CMS.If you can do a RSS feed from articles ( i think theres a RSS addon ), if not theres a possibility to do it with get resources you could use a 3rd party like http://twitterfeed.com/ which does g+ facebook twitter and linkedinI tired when it was a facebook app. Let me try once more. Thanks.
Its simple site but its made in best CMS.If I may, the difficulty of automating this is that you would need to dig into Articles or Collections and find where it is handling the post (or publish) action, so that you can connect the posting to the sharing. That's a bit tricky.Share buttons is good but not automated. And there must be any way to do this with RSS in Modx. I mean a snippet which just check for new feed in RSS and post that to fb etc. If it check feed in regular intervals like, every hour or day, and post.... then it will be good also.
Paulp's suggestion is therefore perhaps the best way, as it avoids this need to connect the two. The rss feed is automatically updated, and this should trigger twitterfeed automatically as well.
The alternative is just to make the share buttons and then click them manually after publishing. But this wouldn't be automated.
Its simple site but its made in best CMS.