By this post, we are not suggesting for a moment that your Android mobile device would be a good substitute as a development platform to your desktop or laptop. All it brings in vision with the existing apps available.
The apps that you are to find below have not been designed to be an alternative mobile solution to typical development desktop software, but are really handy apps to have when you are out and on the move. For a web developer, these apps have enough functionality to write and test and your inspired code ideas.
1. SilverEdit || Source 
SilverEdit is the ultimate web designer tool for Android devices. With SilverEdit, you may Create, Edit, Preview your pages offline or online. Manage, upload and download files through the FTP as well as manage your local files and folders by SilverEdit. SilverEdit supports most known web type documents and the ability to save your documents as whatever file type you would like. Also you may customize the editor to suite you.
2. Learn PHP Fast || Source
Everything you need to know to get a good grip on programming with PHP. PHP is a general-purpose server-side scripting language originally intended for Web development to create dynamic Web pages.
3. View Web Source || Source
With this application, you will be able to view the source of any website. Also you will be able to select text, search for text as well as copy and paste the HTML.
4. Webmaster’s HTML Editor Lite || Source
CSS, PHP, JavaScript, HTML editor with syntax highlighting and code completion. So have a handy source code editor in your pocket. Web Master’s HTML Editor Lite is an HTML, PHP, JS, and CSS editor for web developers.
5. HTML & CSS The Good Parts || Source
With this realistic app, you will learn how to work with HTML and CSS far more effectively than is normal practice for most web developers.
6. Web Developer News PHP, CSS || Source
Web Developer avails you the newest news for web developers and anyone involved in making the websites into a categorized list – from CSS to HTML, PHP, Ruby & Rails, and loads of tutorials to get you inspired.
7. Dev cheats || Source
This free app is a must for every developer by giving a brief compilation of cheatsheets, including: PHP, Python, Ruby on Rails, jQuery, CSS, SEO, Apache, Regular Expressions, SVN, C++, Drupal, HTML5, Javascript, Mysql, WordPress and many more.
8. Console² || Source
Console² allows you display errors filtered by type, language (JavaScript, CSS, XML) and context (Chrome, Content). Also it gives a simple search box (as seen in the History and Bookmarks sidebars), hiding of duplicates, sidebar optimizations, a customizable toolbar and some more accessibility improvements.
9. ConnectBot SSH Client || Source
ConnectBot is a Secure Shell client for the Android platform. Its ultimate goal is to generate a secure connection through which you may use a shell on a remote machine and move files back and forth to your phone.
10. Adobe Shadow || Source
Adobe Shadow is for web developers and designers who develop mobile web projects. This is really for web designers and developers who are targeting mobile browsers.