Proposes adding a new 'subscribe' scheme to x402 to enable subscription-based access, as the current protocol only supports one-time payments. This would allow hybrid monetization, predictable recurring revenue, and AI agent optimization.
## Summary I propose adding a new `subscribe` scheme to x402 that enables services to offer subscription-based access alongside the existing `exact` (pay-per-use) scheme. ## Motivation Many services (SaaS, APIs, content platforms) benefit from subscriptions, but currently x402 only supports one-time payments. Adding subscriptions would: 1. Enable hybrid monetization (pay-per-use + subscriptions) 2. Support predictable recurring revenue 3. Allow AI agents to optimize between payment methods 4. Maintain x402's HTTP-native simplicity ## High-Level Design ### 1. Discovery: Services return both schemes in 402 response (unchanged flow) ```json // 402 Payment Required { "accepts": [ { "scheme": "exact", "maxAmountRequired": "10000" }, { "scheme": "subscribe", "tiers": [ { "id": "basic", "amount": "5000000", "cycle": "monthly" } ] } ] } ``` ### 2. Subscribe (same X-PAYMENT header) ```json { "scheme": "subscribe", "payload": { "action":