Perplexity

Perplexity AI is a search engine rebuilt around AI — every answer comes with numbered citations linking to the exact sources used. Founded in 2022 and valued at over $9 billion by 2025, it has become the go-to tool for anyone who needs AI-generated answers they can actually verify and trust.

The core product is deceptively simple: ask a question, get a clear answer with inline citations, then read the sources yourself. Unlike ChatGPT or Claude which can generate plausible-sounding misinformation, Perplexity grounds every response in live web search results. The free tier includes unlimited basic searches and limited Pro searches per day. Perplexity Pro ($20/month) removes limits and unlocks Deep Research mode.

Deep Research is the standout feature for serious users. Given a complex question — "compare the top five electric vehicle battery manufacturers by energy density and cost per kWh in 2025" — it autonomously runs dozens of web searches, reads the results, synthesizes findings, and produces a multi-page structured report with 30-50 source citations. Tasks that would take a human researcher half a day are completed in under five minutes.