Research methodology

Articles

We start with a practical question and identify what evidence would answer it. We prefer primary documentation, source code, original research, public datasets, and reproducible tests. Articles link to their sources, show publication and update dates, and separate documented facts from our analysis. A vendor claim is evidence of what that vendor says its product does; it is not proof of measured performance. Where we have not tested a claim ourselves, we say so.

Lay of the Land

The directory is a maintained index of products and projects that take part in agent search. It is a selected reference, not a complete census or a ranking. Each entry has a primary source, a short description of its documented role, and a profile with questions to ask when evaluating it. We place an entry in the category that best describes its primary role. A company can appear more than once when it offers distinct products at different layers, so the entry count is not a count of unique companies.

The source-reach table compares a smaller set of source-facing products. Public web, finance, and research marks mean that the linked product material documents search or access to those source domains. They do not imply comparable depth, licensing, freshness, quality, or price. Products such as vector databases and rerankers are in the directory but are not included in that source-reach comparison because they operate on material supplied to them. A dash means we have not cited enough evidence for that mark; it does not assert that a capability is absent.

We mark backtesting only when product documentation describes a way to query source data as it existed at a specified past point in time. A publication-date filter alone does not qualify: it may return a document acquired later, and it does not reconstruct the historical index. Point-in-time features also differ. For example, filtering current search candidates by a stored page version is narrower than replaying the exact ranking that a past search would have returned. Valyu's historical cache can fall back to a live crawl unless historical_cache_strict is set to only. Read the linked documentation and test the behavior against your own evaluation set.

Logos identify products and do not imply endorsement. The directory review date records when we checked the entries, not a guarantee that every linked product is unchanged today. We welcome corrections with a product URL, the claim in question, and a supporting primary source. Confirmed material changes are reflected on the affected page and in its update date.