SmallDevTools - Handy developer tools with a delightful interface
cutestat - Website Stats and Valuation. CuteStat.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
Rankchart - Rankchart is one of the unique websites that allows you to examine your websites or watch competitors and locate rich information about website technologies, site reputation, errors, SEO, and ad-word recommendations.
Profitable developer tools database - A database of 103+ hand-curated profitable developer tools
Site Worth traffic - Site Worth traffic is a cost-effective site that is introduced to estimate the value, daily page views, daily visitors, and daily revenue of a website.