Tonecast is a SaaS platform that shows what AI assistants (ChatGPT, Claude, Gemini and Perplexity) say about a brand, product, person or topic, and which web pages shaped those answers. People now ask AI assistants which product to buy, whether a company is reliable and who the leading options are. One screenshot of one answer says little: answers change from one run to the next. Tonecast measures them properly. • AI Answers: the engines are sampled every week through their official APIs, with web search on, per prompt, engine and language. AI visibility rate, Tone in AI, recommendation rate and share of voice, each with a 95% confidence interval. • Claim check: every factual claim compared with your fact sheet (consistent, incorrect, outdated, unverifiable). • What shaped it: the source graph behind the answers, in three tiers (Cited, Formative, Owned), each page with its influence weight and the reason it was included. You never select sources. • Early signals: whether the sources move before the answers, active only when a significance test corrected for multiple comparisons says so. • Gap & action list: prompts where only competitors appear, and the pages to update or win. Published methodology and quality targets, versioned scores, the full answers behind every number. Data hosted in the EU. Public demo on fictitious brands, no account needed: https://tonecast.io/app/demo