# Probegrade vs. directories that sell placement

Updated 2026-10-17. Category comparison; describes common patterns, not any specific company.

| Dimension | Probegrade | Directories that sell placement |
|---|---|---|
| How sources are ranked | Automated probe measurements | Often by payment, popularity or editorial picks |
| Effect of paying | None on scores; sponsored slots are labeled and separate | Paid listings can appear above unpaid ones |
| What's measured | Uptime, latency, schema validity, freshness, price | Usually nothing measured continuously |
| Audit trail | Hash-chained probe archive per edition | Rarely published |
| Payments for agents | x402 gateway, billed per call | Typically not offered |

More: https://probegrade.com/ratings/ · https://probegrade.com/llms.txt