What We Know About ChatGPT Search Ranking Factors

ChatGPT Search isn't Google Search

ChatGPT Search launched in October 2024 and reached general availability in early 2025. By 2026 it's the second-most-used answer engine after Google's AI Overviews. For agencies advising clients on SEO, "ranking" is no longer a single-engine optimization problem — it's a multi-engine one.

ChatGPT Search uses Bing's index as its primary retrieval source, but the ranking signals it applies on top of that index are substantially different from both Bing's traditional ranking and Google's. This post covers what's confirmed by OpenAI documentation, what's inferred from observed citation patterns over the last 12 months, and what to optimize for if you want to be cited.

Confirmed: how the system works

From OpenAI's published documentation and developer talks:

1. Index source is Bing. ChatGPT Search retrieves from Bing's web index for live results. Pages not indexed by Bing cannot be cited.
2. Citations are required for "Search" mode answers. When the user invokes search (via the search button or by triggering OpenAI's automatic search heuristic), the response must include source citations.