The Half-Life of an x402 Listing

This article examines the stability of x402 listings on Coinbase's platform. It details a measurement conducted between October 3rd and November 7th, 2026, tracking the change in the number of endpoints listed in Coinbase's x402 discovery index. The index decreased from 153 to 56 endpoints over this period, despite no changes in the endpoints themselves.

The article explains that the reduction in the index size is due to listings expiring rather than being removed by the platform. It breaks down the measurement process and findings, noting that listings are removed based on the age of their most recent payment, with a separation of 3.8 days between listings and non-listings. The article also discusses the implications of this expiration mechanism for sellers, suggesting that listings should be viewed as trailing windows of payment status rather than a catalog of existing services.

It emphasizes the importance of understanding the age of the newest payment for each listed listing to anticipate expiry. The piece concludes by stressing that sellers should not treat x402 listings as assets, but rather as indicators of payment activity, and that the index provides a reliable, though not definitive, measure of a service's ongoing status.