Available Deep Research Agents: A Comparison

Overview

Several AI-powered deep research tools are now available to consumers and developers, each with distinct strengths. This report compares the leading options across accuracy, depth, breadth, and accessibility — focusing on tools available via free tiers or Gmail/Google OAuth sign-in.

The landscape is evolving rapidly. As of February 2026, the most capable freely accessible options are Perplexity AI, Google Gemini Deep Research, ChatGPT (with browsing), and Claude.ai. Each takes a different approach to sourcing, synthesis, and citation.

Perplexity AI

Verdict: Best for quick, cited answers.

Perplexity excels at real-time web retrieval with inline citations. Its "Deep Research" mode (Pro tier) runs multi-step searches and synthesizes longer reports. The free tier provides solid single-query answers with source links.

Key strengths:

• Inline citations on every claim

• Real-time web access

• Clean, readable output format

• API available for developers

Limitations: Free tier has query limits; Deep Research mode requires Pro ($20/mo). Reports can be shallow on niche topics.

Google Gemini Deep Research

Verdict: Best depth for long-form research.

Gemini's Deep Research feature (available via Google One AI Premium or free with limitations) creates multi-page research documents with structured sections. It leverages Google Search's index and can produce 10,000+ word reports.

Key strengths:

• Exceptional depth on well-documented topics

• Structured output with table of contents

• Google Search integration (fresh results)

• Free tier available with Gmail account

Limitations: Can hallucinate on niche topics; slower than competitors; export options limited.

ChatGPT with Browsing

Verdict: Most flexible, but inconsistent citations.

GPT-4o with browsing enabled can research topics in real time. The "Deep Research" feature in ChatGPT Pro runs extended multi-step research sessions (up to 30 minutes) and produces detailed reports.

Key strengths:

• Highly capable reasoning and synthesis

• Can follow complex, multi-part research briefs

• Code interpreter integration for data analysis

Limitations: Free tier has limited browsing; Deep Research is Pro-only ($200/mo); citation quality varies.