Error level analysis allows you see to see the difference in quality level, represented by brightness. Things which are very bright have been edited most recently, whilst duller parts have been resaved multiple times. This allows you to see not just which parts of the image have been changed, but in what order the changes occurred.

Bell’s service, DomainNotFound.ca, does offer an opt-out service by using a cookie: Note: In order for opt-out to work properly, you need to accept a “cookie” indicating that you have opted out of this service. If you use a program that removes cookies, you will have to repeat this opt-out process when the cookie is deleted. The cookie placed on your computer will contain the site name: “www.domainnotfound.ca”.

This practice is not only surprising, it is an invasive service that has only one purpose: to raise advertising dollars for Bell.ca. Disappointing to say the least.

See also: Comcast trials Domain Helper service DNS hijacker

• HTML 2 Txt – html2txt: online service to convert web pages to plain text
• W3C HTML validator – This is the W3C Markup Validation Service, a free service that checks Web documents in formats like HTML and XHTML for conformance to W3C Recommendations and other standards.
• Jigsaw – Enter the URI of a document (HTML with CSS or CSS only) you would like validated.
• Backwards Compatibility Checker – Web Page Backward Compatibility Viewer
• Header Checker – Enter a URI for a webpage and we’ll tell you what the headers for that page are. This is useful to check the status code for a webpage for SEO purposes.
• Walidator – Validate your XHTML, HTML, CSS, RSS, RDF…
• WebXCACT – WebXACT is a free online service that lets you test single pages of web content for quality, accessibility, and privacy issues.
• Favicon validator – Favicon Validator is a free online service that can be used to validate favicon files, link tags and related items on web pages. If you’d like to double check the favicon on your web page or if you’re having trouble viewing it, enter your web page address and click “Check”
• Selenium – Selenium is a test tool for web applications. Selenium tests run directly in a browser, just as real users do. And they run in Internet Explorer, Mozilla and Firefox on Windows, Linux, and Macintosh. No other test tool covers such a wide array of platforms.
• Vischeck – Vischeck URL is still under development. We know that it will fail on many websites. For example, it won’t work with sites that do an immediate redirect, use Macromedia Flash, or use certain javascript operations. Frames may also cause problems, but you can run each frame separately to get around this.
• Color Filter – Use the colorblind colorlab to select safe colors earlier in the design process.

• Official Php site – PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML.
• Predefined variables – Since PHP 4.1.0, the preferred method for retrieving external variables is with the superglobals mentioned below. Before this time, people relied on either register_globals or the long predefined PHP arrays ($HTTP_*_VARS). As of PHP 5.0.0, the long PHP predefined variable arrays may be disabled with the register_long_arrays directive.
• CakePhp – Cake is a rapid development framework for PHP which uses commonly known design patterns like ActiveRecord, Association Data Mapping, Front Controller and MVC.
• PEAR – PEAR is a community-driven project governed by its developers. PEAR’s governing bodies are subdivided into the PEAR Group, Collectives, and a President.
• Smarty template engine – One of Smartys primary design goals is to facilitate the separation of application code from presentation. Typically, the application code contains the business logic of your application, written and maintained in PHP code. 

• Official MySQL Documentation – The MySQL Reference Manual covers most areas of MySQL use. This manual is for both MySQL Community Server and MySQL Enterprise Server. If you cannot find the answer(s) from the manual, you can get support by purchasing MySQL Enterprise, which provides comprehensive support and services.
• PhpMyAdmin – phpMyAdmin is a tool written in PHP intended to handle the administration of MySQL over the Web. Currently it can create and drop databases, create/drop/alter tables, delete/edit/add fields, execute any SQL statement, manage keys on fields, manage privileges,export data into various formats and is available in 50 languages. GPL License information.
• PosgreSQL docs – PostgreSQL is a powerful, open source relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness.
• PhpPGAdmin – phpPgAdmin is a web-based administration tool for PostgreSQL. It is perfect for PostgreSQL DBAs, newbies and hosting services.
• SQL Notes – Some helpful hints on administrating and working with major linux sql-databases.

• Keyword suggestion tool – This is a handy little tool will show you the results of your query from both Wordtracker and Overture for determining which phrases are searched most often.
• Keyword tracker – This utility can be used to check search engines (currently supporting Google, Yahoo and MSN) for search engine ranking and track those ranking historically, which as you probably know is critical when doing Internet marketing for your website(s).
• Co-op ad network - Many sites have a lot of content for users which could be used for a shared advertising network. So the way I figured it, is why not use it and create the first cooperative advertising network (it’s free by the way).
• Overture keyword tool – Not sure what search terms to bid on? Enter a term related to your site and we will show you.
• Wordtracker – With Wordtracker you’ll know which are the best keywords to drive more traffic to your sites.

• NSI – Web Hosting, web site design and domains from Network Solutions
• Sedo Domain parking – Sedo is the leading marketplace for buying and selling domain names and websites
• Country code list – VisiBone’s “split list” of Internet Country Codes
• 3Char domains – Domain Name Valuations have always been a tricky task, and it’s often amazing to see the vast differences in valuations suggested from one source to another.
• Domain Tools & much more – Whois history database, Detailed uptime reports on providers, Patent pending reverse IP search, Alerts when a domain use trademarks, DNS stuff, whois, traceroute, and ping.

• Domain lookup – Ajax-powered instant domain search. Start typing and you’ll see if the domains you want to buy are available or not.

• Project IP – Detailed information about you and your computer. In addition to your IP address, Project IP lists just about everything a webserver can find out about your computer. Enjoy!
• Future pagerank – This tool will query Google’s various data centers to check for any changes in PageRank values for a given URL. Usually all data centers will output the same, but if queried during an update, you might get a glimpse of any upcoming changes in your chosen URL’s PageRank value.
• Page Strength – The tool is designed to satisfy the curiosity of webmasters, surfers and web marketing professionals seeking a better metric to quickly assess a site/page’s relative importance and visibility.
• Web page analyzer – The script calculates the size of individual elements and sums up each type of web page component. Based on these page characteristics the script then offers advice on how to improve page load time.
• WayBack Machine – Browse through 85 billion web pages archived from 1996 to a few months ago.
• Domain to IP – Enter domains or full URLs (one per line) to look up their IP addresses. You may enter up to 50 domains.
• Verify pagerank – Different websites offer them every day – those “Super-PageRank Domains”. But beware: More and more dubious providers try to sell completely worthless domains to you with bogus tricks. Use this chance to check if the displayed PageRank is real.
• Web Form Factory – Web Form Factory is an open source web form generator which automatically generates the necessary backend code to tie your form to a database.
• RFC Ref – Internet RFC/STD/FYI/BCP Archives
• Alexa – The Top 10 Sites moving up or moving down in the traffic rankings, as measured by the change in the number of users visiting the site.
• Google dance tool – Google Datacenter Watch Tool
• Visual pagerank – View the PageRank of links visually rather than in text.
• Rusty brick – This tool attempts to determine a future Google PageRank value of a particular site. In other words, we try to determine the PageRank value of the URL you enter below, as it would be after the next Google PageRank update. The tools does several calculations to come to this figure.

• Getting started with HTML – a short introduction to writing HTML. What is HTML? It is a special kind of text document that is used by Web browsers to present text and graphics.
• HTML 4.01 – This specification defines the HyperText Markup Language (HTML), the publishing language of the World Wide Web. This specification defines HTML 4.01, which is a subversion of HTML 4.
• HTML Characters – Alpha Codes
• Use the right DOCTYPE – In case you aren’t familiar with the DOCTYPE element, it’s quite simply an element used to declare what language (and its level) a document uses, and optionally what document type definition (DTD) is to be used in its handling.
• All about Character encoding – a quick summary of key information related to character encodings in HTML and XML.
• HMTL & CSS tutorial by example – htmlPlayground
  XHTML+CSS REFERENCE BY EXAMPLE
  0.3 BETA

If you create your archive using php, you can include this bit of code on your pages to make each one, just one click away from displaying source code:

1. Create this bloc of php in the top of the template file

<?phpfunction curPageURL() {
$pageURL = ‘http’;
if ($_SERVER["HTTPS"] == “on”) {$pageURL .= “s”;}
$pageURL .= “://”;
if ($_SERVER["SERVER_PORT"] != “80″) {
$pageURL .= $_SERVER["SERVER_NAME"].”:”.$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
} else {
$pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
}
return $pageURL;
}
?>

2. Add this link to all your pages

<a href=”view-source:<?php echo curPageURL(); ?>” target=”_blank”>View source of current page</a>