Search for a username across multiple social media and developer platforms (GitHub, Reddit, X/Twitter, Instagram, LinkedIn, TikTok, Facebook, YouTube, Pinterest, Telegram, Discord, Mastodon, Keybase, HackerOne, GitLab, Medium) to check if accounts exist. Use this for OSINT investigations to map a person's online presence or verify identity claims. Returns JSON with fields: username, total_found (count), and platforms (array of objects with name, exists (boolean), url, and status_code). Read-only HTTP checks to public profile pages, no authentication required.