Add per-request agent payment headers to existing REST APIs

Add per-request agent payment headers to existing REST APIs targets a $3.6B = 600,000 API providers × $6K ACV (annualized tooling/billing + integration revenue per provider) total addressable market with medium saturation and a year-over-year growth rate of 25% YoY — growth estimate based on RapidAPI and commercial API economy reports showing strong demand for API monetization and metered billing.

Key trends driving demand: Autonomous agents are increasing programmatic API traffic — this creates demand for per-request billing because traditional subscription models aren't granular enough.; API-first products are monetizing with metered and usage-based billing models — this trend makes middleware that supports micro-billing valuable.; Developers prefer turnkey SDKs and gateway plugins that minimize engineering work, creating an opportunity for integration-focused products.; Cloud-native, serverless architecture reduces the cost of inserting middleware, making hosted pay-per-request enforcement practical for more providers..