AI Deep Research Comparison, ChatGPT vs Gemini vs Perplexity vs Claude vs Grok

“Deep research” is the agentic mode in a chatbot that spends several minutes reading tens of web pages and then writes a long, structured, cited report, a different job from quick AI search, which answers in seconds from a handful of pages. This page lines up the five modes a Sri Lankan student, analyst or freelancer actually chooses between: ChatGPT Deep Research, Gemini Deep Research, Perplexity Deep Research, Claude Research and Grok DeepSearch.

1. The dataset

The comparison is a curated, cited table, not a benchmark and not an opinion score. Each row records the underlying model, the cheapest plan that unlocks deep research, the free-tier allowance, the paid run limit, typical report length, citation style, export targets, private-data connectors and real-time-web access, taken straight from the vendor's own pages. Because deep-research limits change often, every figure is dated with a 2026-07-05 LAST_VERIFIED stamp.

2. The recommender

The tool is a transparent, rules-based recommender, no live API calls, no scoring model. It runs in two steps:

1. Filter.For each tool it finds the cheapest plan whose price is within your budget, whose monthly run limit meets your minimum, and, if you asked, is free. Tools without document export or private connectors are dropped when you require those. A tool with no qualifying plan is set aside as a “near miss” with the exact constraint it failed.
2. Rank.Survivors are sorted by a key order tied to your use case, Academic report leads on report depth then export then citation quality; Market research leads on runs per month then sources per run; News & real-time leads on live-web freshness. Ties break by lower price, then more runs.

The top survivor becomes the recommendation and the second the runner-up. If nothing clears every filter, the tool shows the nearest options and which constraint each fails, so the page never dead-ends.

3. The LKR line is indicative

The recommendation card multiplies the USD plan price by a fixed CBSL middle rate of Rs 300per USD to show an approximate rupee cost. This is a constant, not a live feed, your bank's rate plus FX margin will differ by a few percent. For a live USD-to-LKR rate with Wise, Payoneer and Skrill fees, use the Freelancer USD-LKR calculator in Related tools.

4. Cross-checks

The data module exports verifyWorkedExamples() , which recomputes the worked examples below, including the fractional budget, negative-input error, runs-boundary and no-match cases, and verifyDatasetIntegrity(), which asserts unique ids, non-negative prices and runs, axis scores in range, and an https source on every row. A typo in a quarterly price update fails a test instead of shipping silently.

• OpenAI: ChatGPT Deep Research FAQ (run limits by plan)
• OpenAI: ChatGPT pricing (Free, Plus, Pro)
• Google: Gemini Deep Research overview & Docs export
• Google: AI plans (AI Pro, AI Ultra)
• Perplexity: Introducing Perplexity Deep Research
• Perplexity: Help Center & FAQ (free vs Pro limits)
• Anthropic: Claude Research
• Anthropic: Claude pricing (Pro, Max)
• xAI: Grok plans & DeepSearch (Free, SuperGrok)
• Columbia Journalism Review (Tow Center): AI citation-accuracy study
• Central Bank of Sri Lanka: Exchange Rates (indicative LKR line)

Plans, run limits, citation behaviour and export options were last cross-checked against the official sources on 2026-07-05. Consumer tiers only; Team, Enterprise and API plans are out of scope. LKR is indicative at Rs 300/USD.