Foxden is an idea validation tool aimed at founders, indie hackers, and anyone who wants a reality check before investing time in a concept. Type in your idea and it runs a 5-axis AI score covering market opportunity, uniqueness, feasibility, revenue potential, and timing. Alongside that, it searches seven platforms — App Store, Google Play, Product Hunt, Reddit, GitHub, and more — to surface existing competitors you might have missed. It also estimates market size and surfaces specific improvement suggestions. A swipe-based derivative idea feature lets you explore AI-generated variations on your core concept, useful for pivoting or narrowing a niche. Built by a solo developer, it's priced accordingly: free for three ideas, $3.99/month for unlimited access.