Here are some links and tools I've found useful for web development.
Ultimate CSS Gradient Generator : online tool to easily generate CSS gradients (with cross-browser compatibility)
Debuggex : online tool to visualize regular expressions. Must-have to debug hard-to-read regexps.
Flexbox CSS Tricks : A graphic memento for CSS flexbox positionning model.
HTML Color Codes : Memento of 140 named color codes.
CSS Compressor : online tool to minify CSS data (removes comments and newlines).
BrowserStack : online tool for website testing (on many desktop and mobile browsers). free trial with registration1.
Mobile1st : online tool for website testing (mobile browsers). free trial with registration2.
Ico Converter : quickly convert a picture to ICO format (with multiple sizes).
UTF Cast : a desktop tool to batch convert files to UTF-8/16/32 encoding. Free application is limited to UTF-8 output and missing non-critical functionnalities.
Base64 Image Encoder : a online tool to convert a picture (1MB max) to a Base64-encoded data uri. Useful for inlining icons directly in html source code, when CSS or an URL is not an option.
Base64 Decode/Encode : online tool to encode/decode base64 data.
Unix Timestamp Converter : convert a Unix timestamp to a human-readable date.
RGB Color Converter : convert a RGB-formatted color to CMJK.
X-Icon Editor : Simple online icon editor ; can handle 4 icon sizes in a single ico file. Useful for providing custom favicons.
Online JSON Viewer : Format a JSON string to a human-readable string (with padding and newlines) or tree view.
XML Viewer : Format XML data to a human-readable data or tree view.
