The proof class assigned to a source is not a fixed property of the source — it depends on what claim the source is being used to support. The same source can carry different proof weight for different claim types. A regulatory database entry is high proof weight for confirming regulatory compliance status (Class 3) but carries no proof weight for establishing vendor capability beyond what the regulation specifically addresses. The proof class column below reflects the primary class and typical conditions under which each source qualifies.
Class 1 — Direct Documentation Sources
Official product documentation
Vendor-published feature documentation, technical specifications, API references, and product pages. High proof weight for confirming that documented features exist as described. Cannot establish independent market position.
Class 1
Pricing and terms pages
Publicly posted pricing schedules, terms of service, SLA documents, and contract terms. High proof weight for confirming stated commercial terms. Must be current — archived or outdated pages noted as such.
Class 1
Official press releases
Vendor-issued press releases and official announcements. Confirm that a vendor made a specific public statement. Do not independently corroborate the claims made in those statements.
Class 1
SEC and regulatory filings
Publicly accessible regulatory filings including SEC disclosures, annual reports, and official financial statements. High proof weight for confirming financial facts, material risks, and regulatory disclosures that companies are legally required to make accurately.
Class 1 / Class 3
Class 2 — Independent Review Platforms
G2 (g2.com)
Software review platform with documented quality controls including verified reviewer requirements and vendor relationship disclosures. Class 2 for aggregated pattern signals at sufficient volume. Individual reviews are Class 6.
Class 2
Capterra (capterra.com)
Software review platform. Class 2 for aggregated patterns. Note: Capterra accepts vendor participation fees for placement in category listings — this affects the listing order but not individual review content. The aggregated review signal is assessed independently of listing placement.
Class 2
Trustpilot (trustpilot.com)
Consumer review platform with documented quality controls. Class 2 for aggregated pattern signals in categories where consumer-facing service quality is the relevant dimension. Volume and recency requirements apply by category.
Class 2
Google Business Reviews
Publicly accessible aggregated review signals for business entities. Class 2 for aggregated patterns where local or direct service quality is the relevant claim. Not applicable for validating software capability claims.
Class 2
Class 3 — Independent Analysis and Regulatory Sources
Gartner research (public)
Publicly accessible Gartner analysis and Magic Quadrant outputs. Class 3 for market-level context and relative positioning when the referenced content is independently produced and not vendor-commissioned. Gartner's vendor relationship policies are assessed per publication.
Class 3
Forrester public research
Publicly accessible Forrester Wave and research outputs. Class 3 conditions apply. Independence assessment required for each reference — vendor-commissioned Forrester research is reclassified as Class 6.
Class 3
Government and regulatory databases
Public regulatory records from SEC EDGAR, FDA databases, FTC enforcement records, state licensing databases, and equivalent official sources. High proof weight for confirming regulatory status, compliance, and official actions.
Class 3
Independent journalism
Coverage from editorially independent news organizations with documented editorial standards. Class 3 for factual claims reported by journalists with documented sourcing. Editorial interpretation within journalism is noted as such. Does not apply to sponsored content or vendor-placed coverage.
Class 3
Academic and peer-reviewed research
Peer-reviewed research from recognized academic institutions and journals. Class 3 for factual claims within the scope of the research. Funding source independence is assessed — industry-funded research with undisclosed vendor relationships is reclassified.
Class 3
Class 4 — Community and Practitioner Sources
Reddit (professional communities)
Practitioner discussions in professional subreddits with documented community standards. Class 4 when two or more independent practitioner accounts corroborate the same pattern. Individual accounts are anecdotal until corroborated. Vendor-operated communities are excluded.
Class 4
Hacker News discussions
Technical community discussion at news.ycombinator.com. Class 4 for technical pattern signals in software categories when corroborated across multiple independent participants. Not applicable for business claims or non-technical assertions.
Class 4
LinkedIn practitioner discussions
Public professional discussions from practitioners with verifiable professional profiles. Class 4 when corroborated across multiple independent contributors. Vendor employee commentary is noted and assessed for objectivity.
Class 4
Class 5 — Market Signal Tools
Google Trends
Publicly accessible search interest data from Google. Class 5 for establishing relative market attention and trend direction over time. Not applicable for confirming vendor capability claims.
Class 5
Ahrefs / SEMrush (organic signals)
Publicly observable organic search signal data. Class 5 for relative market presence and category attention indicators. Not applicable for confirming capability or quality claims.
Class 5
SimilarWeb public data
Publicly available traffic and engagement estimates. Class 5 for market presence indicators. Treated as approximate signal data, not precise measurement, due to estimation methodology.
Class 5
Source independence assessment
The proof class of a source is assessed for each use, not assumed from the source type. Sources that qualify as Class 3 in one context may be reclassified as Class 6 (submitted evidence) if a commercial relationship between the source and the vendor is identified. Source independence assessments are documented in individual validation outputs. To report a source independence concern, contact [email protected].