Perfect vs mailfloss

Nodal.js

A web server for Node.js that was built to make developer's life easier

lighttpd

A lightweight and high-performance event-driven web server

NGINX

A high performance free open source web server

XAMPP

An open-source cross-platform web server that is used primarily for local development

Puma

A Ruby/Rack web server built for parallelism

ZeroBounce

An email validation, scoring, and deliverability platform

NeverBounce

Email Marketing

SparkPost

Email Marketing

DeBounce

Email Verification Service

Kickbox

Smarter Email Verification for Marketers and Developers