Here is a list of tools I use on a daily basis and I know I can trust, I have used hundreds of different tools over the last 10 years and this list is continually changing, if I find a new feature that I think could be beneficial to I'll add it to this list and likewise if something gets outdated I'll remove it from this list.
Development Languages
Python

Python is a programming language that lets you work quickly and integrate systems more effectively.
Java

GTmetrix is a free tool that analyzes your page's speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers advice how you can improve your site speed.
JQuery

jQuery is a cross-platform JavaScript library designed to simplify the client-side scripting of HTML.jQuery is the most popular JavaScript library in use today.
Javascript

In computing, JavaScript is a high-level, dynamic, untyped, and interpreted programming language. It has been standardized in the ECMAScript language specification.
PHP

PHP is a server-side scripting language designed primarily for web development but also used as a general-purpose programming language. One of it's main uses is WordPress.
MYSQL

MySQL is a database system used on the web; MySQL is a database system that runs on a server; MySQL is ideal for both small and large applications
Content Management Systems
WordPress

WordPress is web software you can use to create a beautiful website, blog, or app. We like to say that WordPress is both free and priceless at the same time.
Joomla

Joomla! is an award-winning content management system (CMS), which enables you to build Web sites and powerful online applications.
Email marketing
Infusionsoft

Infusionsoft is a private company that offers an e-mail marketing and sales platform for small businesses, including products to streamline the customer lifecycle.
Mailchimp

Online email marketing solution to manage subscribers, send emails, and track results. Offers integrations with other programs.
Get Response

Powerful tools built for success and ease of use,Constantly updating there software with new an innovative features
Landing Page Builders
Optimize Press

OptimizePress automatically generates fully responsive pages for you when you with no extra work. So now your landing pages, sales pages and membership sites will all look stunning on any device
Leadpages

Leadpages generates leads and sales for your business on the web, in emails, via text messaging, and on social media. Meet the powerful tools that make it possible.
Social Media
Hootsuite

Manage all your social profiles, promote your brand, generate quality leads, and increase website traffic — all from one easy to use tool. Perfect for everyone, from small business to large enterprise.
Data Analysis
Google Analytics

Get the data you need to make intelligent marketing and business decisions with Google Analytics. Available for websites, apps, and enterprise businesses.
GTmetrix

GTmetrix is a free tool that analyzes your page's speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers advice how you can improve your site speed.