Pay-per-call ACH endpoint on Base via x402 — $0.02/request in USDC, no API keys required.
What it does
lowpaymentfee.com hosts a collection of pay-per-request API endpoints settled via the x402 protocol on the Base network using USDC. The specific endpoint at `/api/v1/ach/21` is listed under "Premium API Access" and accepts POST requests. Payment is made per-call with no API keys, no rate limits, and no upfront commitments — each request costs $0.02 (20,000 base units of USDC with 6 decimals).
The broader lowpaymentfee.com platform advertises endpoints across several categories: Data & Analytics (metrics, reports, data export, insights), AI & Machine Learning (sentiment analysis, text summarization, classification, embeddings), Finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and Infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced at $0.02 per request and settle on the Base L2 network.
Documentation is extremely sparse — the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail. There is no OpenAPI schema, no request/response examples, and no description of what the `/api/v1/ach/21` endpoint actually returns. The endpoint is live (returns a valid x402 402 challenge), but without documentation it is unclear what data or functionality "Premium API Access" provides. The "ach" path segment suggests it may relate to ACH (Automated Clearing House) payment processing or data, but this is speculative.
Capabilities
Use cases
- —Accessing premium ACH-related data or functionality on a per-request basis
- —Integrating pay-per-call APIs into agent workflows without managing API keys
- —Testing x402 protocol payment flows on Base network
Fit
Best for
- —Developers experimenting with x402 pay-per-request patterns
- —Agents needing keyless, on-demand API access settled in USDC
- —Low-volume or sporadic API consumers who prefer no subscriptions
Not for
- —Users who need detailed API documentation or request/response schemas before integrating
- —High-volume consumers who would benefit from bulk pricing or rate-limited plans
- —Anyone requiring non-crypto payment methods
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/ach/21 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is zero documentation on what the endpoint does, what inputs it accepts, or what it returns. No OpenAPI schema, no examples, and the docs pages are empty. The purpose of '/api/v1/ach/21' is entirely unclear.
Warnings
- —No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet' with no content.
- —No OpenAPI or request/response schema provided; impossible to know what this endpoint accepts or returns.
- —The purpose of '/api/v1/ach/21' ('Premium API Access') is undefined — the 'ach' path is ambiguous and could relate to ACH payments or be an arbitrary label.
- —Cannot verify what data or service is actually delivered after payment.
Citations
- —The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/ach/21
- —All endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —The platform offers endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/ach/21