Both are favorites of people who outgrew ChatGPT defaults — for opposite reasons. Perplexity is what search should have become; DeepSeek is what free AI became. The choice is about whether your questions live on the web or in your head.
Perplexity for cited, current answers from the live web (free tier; Pro $20). DeepSeek for unlimited free frontier-class reasoning and coding. Many researchers run both — combined cost: still just $20.
By Perplexity AI. Full Perplexity profile →
By DeepSeek AI. Full DeepSeek profile →
Best for: Research with verifiable sources, fact-checking, exploring unfamiliar topics
Weakness: Less suited for creative writing or open-ended chat
From $0 (free)/mo. Top tier: $200/mo.
Best for: Math, logic, coding for users on a budget — or curious experimenters
Weakness: Hosted in China; data residency may matter; less polished UX
From $0 (free)/mo. Top tier: $—/mo.
Pick Perplexity when answers must be current and checkable: live web search, citations on every claim, 300+ Pro searches a day. Its free tier is generous too — pay only when research is daily work.
Pick DeepSeek for thinking rather than finding: math, code, analysis and drafting with frontier-class reasoning, unlimited and free. It doesn't search the live web with citations — that's the whole trade.
Questions about the world right now → Perplexity. Questions a smart mind can reason through → DeepSeek, for free.
At reasoning and coding, yes. At research, no — DeepSeek can't match live web search with citations, which is Perplexity's entire product.
If research with sources is daily work, yes — they don't overlap much. If you mostly want a strong thinking partner, DeepSeek free may be all you need.
Both are the best free tiers in AI: Perplexity's unlimited quick searches, and DeepSeek's fully unlimited everything.