# Re · Research Engine — element 18 of 58 > The web, pre-digested. Turns open questions into sourced answers. - **Group:** 4 · Knowledge & Memory - **Necessity:** Essential - **Price band:** $ · under $30/mo - **Maturity:** Stable - **Edition:** v2026.Q3 · verified 2026-09-13 ## Leading tools (v2026.Q3) - **Perplexity** — cited answers, daily default - **ChatGPT deep research** — deepest reports, biggest reach - **Gemini Deep Research** — free-tier depth, workspace-grounded - **Claude Research** — agentic search, your context - **Elicit** — science literature, systematic rigor ## Our take Deep-research modes changed the job: you now delegate the reading, not just the searching. Keep the judgment. ## Combines with Fm, Kw - Guide: [Best deep research tool for founders (2026)](https://elems.ai/best/best-deep-research-tool-for-founders.html) ## The top 5 — deep dossier (verified 2026-09-13) Perplexity, for the daily habit — the category it invented is now a $500M-ARR, $21B business, and no rival matches its speed-to-cited-answer across free, Pro, and the Comet browser. But deep-research modes changed the job in 2025–26: for the one exhaustive report that replaces a day of reading, ChatGPT deep research (rebuilt on a GPT-5.2-base in Feb 2026) is the strongest single tool. Gemini Deep Research wins when the budget is $0 or the answers live in your Gmail/Drive; Claude Research wins when your work context already lives in Claude and MCP connectors; Elicit wins the moment the question is scientific literature rather than the open web. Keep the judgment — every one of these still hallucinates at the margins. 1. **Perplexity** (Perplexity AI) — Free · Pro $20/mo · Max $200/mo · Enterprise Pro $40/seat · usage-based agent credits on Max. Best for: The default daily research engine — fast, cited answers dozens of times a day, with Research mode and the Comet browser folding search into everything you do. Why: The answer-engine category leader by every measure: $500M ARR (Apr 2026, up 335% YoY), $21.2B Series E-6 valuation (early 2026), 780M queries/month back in May 2025 and 100M+ MAU since. Comet — free since Oct 2025, iOS since Mar 2026 — turns the browser itself into the research surface, and the Feb 2026 subscription-first shift bet the company on answer quality over ads. Watch: Valuation runs ~40x ARR against Google AI Mode giving cited answers away for free inside Search. Publisher scraping-and-attribution fights (News Corp et al.) are unresolved, and answer-level citation accuracy still demands spot-checking. Max/Enterprise pricing was 404 on the vendor page to our crawler — verified via Sacra only. [https://www.perplexity.ai](https://www.perplexity.ai) 2. **ChatGPT deep research** (OpenAI) — In ChatGPT plans: Free (limited/lightweight) · Plus $20/mo · Pro $200/mo (maximum quota) · Business per-seat. Best for: The single exhaustive report — 5–30 minutes of autonomous browsing that replaces a day of reading, footnoted end to end. Why: The mode that defined the deep-research category (Feb 2, 2025, 26.6% on Humanity's Last Exam vs o1's 9.1%) and the most heavily iterated since: rebuilt on a GPT-5.2-based model in Feb 2026 with steering, source limits, and MCP-server data connections. Distribution through ChatGPT's enormous user base makes it the deep-research mode most founders already have. Watch: OpenAI itself warns it "occasionally makes factual hallucinations" and states rumors without conveying uncertainty. Quotas went opaque in 2026 — the pricing page now says only "limited/expanded/maximum"; the last published numbers (Jun 2025) were Pro 250/mo, Plus 25, Free 5 lightweight. Max quota costs $200/mo. [https://openai.com/index/introducing-deep-research/](https://openai.com/index/introducing-deep-research/) 3. **Gemini Deep Research** (Google) — Free tier · AI Pro ~$20/mo (expanded access) · AI Ultra ~$250/mo (highest limits + report visuals). Best for: Free-tier depth and research grounded in your own Gmail, Drive, and Chat alongside the open web. Why: The distribution and grounding play: the original deep-research mode (Dec 2024), now Gemini 3-powered, live in 150+ countries and 45+ languages, and the only top pick that browses your Workspace data and hundreds of websites in one run, with audio overviews of the finished report. The free tier makes it the zero-budget default. Watch: Numeric quotas are unpublished — 'higher limits' is all Google commits to. Report visuals (charts, simulators) are gated to the ~$250/mo Ultra tier and vanish entirely if you include Workspace sources. The 18+ requirement and Keep-Activity dependency for report history are easy to trip over. [https://gemini.google/overview/deep-research/](https://gemini.google/overview/deep-research/) 4. **Claude Research** (Anthropic) — Included in all paid Claude plans: Pro $17–20/mo · Max from $100/mo · Team $20/seat · Enterprise. Best for: Sourced investigation woven into the assistant where your work already lives — chained agentic searches over web plus MCP connectors, Workspace, and enterprise document catalogs. Why: Launched Apr 15, 2025 as a Max/Team/Enterprise beta, now on every paid plan down to Pro. Its distinct approach — multiple searches that build on each other with easy-to-check citations, plus Gmail/Calendar/Docs integration and admin-enabled RAG cataloging on Enterprise — makes it the strongest pick for research entangled with your own context rather than the open web alone. Watch: No dedicated quota: Research shares your plan's normal usage limits and burns them noticeably faster. Output favors verifiable synthesis over the hour-long, hundred-source reports ChatGPT and Gemini produce — a feature for checking, a limit for exhaustiveness. [https://claude.com/blog/research](https://claude.com/blog/research) 5. **Elicit** (Elicit (spun out of Ought)) — Free (limited agent/reports) · Pro $49/mo · Scale $169/mo · Enterprise custom. Best for: When the question is scientific — literature search, screening, and data extraction over 138M papers with systematic-review rigor instead of open-web vibes. Why: The scientific-literature research engine with real workflow depth: Research Agent, Reports, and automated Systematic Literature Reviews across 138M papers and 545k clinical trials, trusted by 5M+ researchers. Enterprise tier claims PRISMA-grade screening/extraction accuracy — the standard actual evidence teams are held to — with vendor-reported 80% time savings on reviews. Watch: Vendor-claimed metrics (5M researchers, 80% savings) lack third-party audit. Literature-only — it will not research the open web, markets, or competitors. Serious use lands on Pro fast, and figure extraction is gated to the $169/mo Scale tier. [https://elicit.com](https://elicit.com) ### How to choose - If You ask dozens of sourced questions a day and want the fastest answer-with-citations loop → Perplexity Pro at $20 — and let Comet make the browser the research surface. At $0, Gemini's free tier is the fallback. - If The deliverable is one deep, footnoted report that replaces a day of reading → ChatGPT deep research — Plus covers most founders; only report-a-day power users need Pro's maximum quota at $200. - If Half the answer lives in your own inbox, docs, and meetings → Gemini Deep Research with Workspace sources — or M365 Copilot Researcher in Microsoft shops, or Claude Research if your context is already wired up via MCP connectors. - If The question is scientific, clinical, or will be peer-reviewed → Elicit for the workflow (screening, extraction, PRISMA-grade reviews); Consensus for fast evidence checks; Undermind when discovery itself is the hard part. - If Research is a feature of your product or agent, not a tab you open → Buy the API layer, not a subscription: Exa for index quality, Parallel for price-performance ($1/1k entry), Tavily for agent-framework ubiquity. ### The field (19 more) Exa, Consensus, You.com / ARI, Kagi, Undermind, SciSpace, scite, Liner (dead), M365 Copilot Researcher, Grok research, Tavily (acquired), Parallel Web Systems, STORM / Co-STORM, NotebookLM, Google AI Mode, Brave Search API, Phind (fading), Neeva (dead), Elicit (Ought era) (renamed) Full dossier data: https://elems.ai/e/re.json --- Source: [elems.ai](https://elems.ai/e/re.html) — the periodic table of the AI-led startup. Data: https://elems.ai/elements.json (CC BY 4.0, cite elems.ai).