Konstantin Obenland

This plugin needs Jetpack by WordPress.com to be activated and its Sharing module to be enabled. 
Enter the desired Twitter usernamen in Settings -> Sharing. It will then be appended, every time a visitor shares your content on Twitter
See the <a href="https://dev.twitter.com/docs/tweet-button" title="Tweet Button" rel="nofollow ugc">Tweet Button documentation</a> for details.
<h4>Translations</h4>
I will be more than happy to update the plugin with new locales, as soon as I receive them! 
Currently available in:
<ul>
<li>English</li>
</ul>

Jetpack Twitter Via

Adds 'via @username' to the Tweet Button provided in "Jetpack by WordPress.com"

Automattic

robfelty

Anna McPhee

Greg Ichneumon Brown

kangzj

bluefuton

Dognose

a8ck3n

Jason Moon

trakos

Incredibly powerful and customizable, Jetpack Search helps your visitors instantly find the right content – right when they need it.
Jetpack Search is an easy-to-use WordPress search plugin that enhances the default site search functionality provided by the CMS. Thanks to advanced site search tools, your visitors will experience the best search experience you can offer.
From real-time search filtering and faceting, to instant search results, Jetpack Search has all the features and options for best site search usability and results.
Note: Jetpack Search is free to use for sites with up to 5000 documents and 500 search requests per month. Beyond that, a Jetpack Search subscription, or a Jetpack plan subscription that includes Search is required to use this plugin.
LESS DIGGING, MORE FINDING
Do you have a WordPress site with thousands of posts, pages, and products? No problem. Thanks to a powerful search engine, Jetpack Search helps visitors find exactly what they’re looking for — fast.
KEEP PEOPLE READING & BUYING
Give your visitors instant search results and advanced filtering to help them find what they need and stay longer on your site.
People on eCommerce sites are 2x more likely to purchase something when they search.
FINELY-TUNED SEARCH FOR YOUR SITE
Jetpack Search is a completely customizable WordPress site search plugin, so your visitors get a search experience that blends in seamlessly with your site design.
WHY CHOOSE JETPACK SEARCH?
<ul>
<li>Highly relevant search results organized by modern ranking algorithms</li>
<li>Boosted and prioritized results based on your site’s search stats</li>
<li>Instant search and filtering without reloading the page</li>
<li>Site search filters and facets (by categories, tags, dates, custom taxonomies, and post types)</li>
<li>Improved theme compatibility for both mobile and desktop</li>
<li>Real-time indexing, so your search index is updated within minutes of changes to your site</li>
<li>Integrates seamlessly with WooCommerce</li>
<li>Support for all languages, and advanced language analysis for 38 languages</li>
<li>Highlighted search terms on comments and post content</li>
<li>Fast and accurate spelling correction</li>
</ul>
WITH 💚 BY JETPACK 
This is just the start!
We are working hard to bring more features and improvements to Jetpack Search. Let us know your thoughts and ideas!
<h3>Testimonials</h3>
“I like having a search experience that is sortable, filterable, and feels like it’s integrated natively into the site. Jetpack Search does all of this, but most importantly, it returns great results without heavy configuration.” – Chris Coyier, Web Design Expert (codepen.io / ShopTalk Show)
“If people can get the answers they want quickly without having to email me, it’s pure gold and it makes my job easier. I’m advertising it in my client consultations and telling people to use it because it actually works.” – Kylie Mawdsley, Interior Design Consultant (Kylie M. Interiors)

Jetpack Search

Both the search functionality and plugin support are excellent.

Only limitation is in terms of design of the light box (popup) showing the results and filters. But then, that ensures the ease of integration...

Great functionality and support

Easily add cloud-powered instant search and filters to your website or WooCommerce store with advanced algorithms that boost your search results based …

Jetpack Twitter Via vs Jetpack Search