x402-gated transaction receipt endpoint on Base, paid per-call in USDC.
What it does
This endpoint at lowpaymentfee.com provides access to a transaction receipt (resource ID 308) behind an x402 paywall. The broader lowpaymentfee.com platform advertises a suite of API categories including Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and payment settled in USDC on the Base network.
The specific endpoint `/api/v1/transactions/308/receipt` returns a 402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02 USD. Payment is made via the x402 exact scheme: the caller includes an X-PAYMENT header with a signed payment proof, and the server returns the receipt as application/json. The challenge specifies a 300-second timeout and accepts POST requests.
Documentation on the site is extremely thin — the /docs, /pricing, /api, and /README pages all render only a "Connect wallet" prompt with no further content. There is no OpenAPI spec, no request/response schema beyond the x402 outputSchema stub, and no description of what fields the receipt JSON contains. The platform appears to be a demonstration or early-stage x402 marketplace rather than a mature production API.
Capabilities
Use cases
- —Retrieving a transaction receipt by paying $0.02 in USDC on Base
- —Demonstrating x402 protocol payment flows for agent-to-agent commerce
- —Integrating pay-per-call APIs without traditional API key management
Fit
Best for
- —Developers experimenting with x402 payment protocol
- —Agents that can sign USDC payments on Base
- —Use cases needing keyless, pay-per-request API access
Not for
- —Production workloads requiring documented response schemas and SLAs
- —Users without a Base-compatible wallet or USDC balance
- —High-throughput batch processing where per-call payment overhead is impractical
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/transactions/308/receipt
# Returns 402 with x402 challenge. Include X-PAYMENT header with signed USDC payment proof to receive the receipt.Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but documentation is essentially nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI spec, no response schema, and no explanation of what the transaction receipt contains. The listing is effectively a stub.
Warnings
- —No documentation available — /docs, /pricing, /api, and /README all render only 'Connect wallet'
- —No OpenAPI or response schema provided; the contents of the receipt JSON are unknown
- —The specific endpoint path (/transactions/308/receipt) suggests a single fixed resource rather than a parameterized API
- —Platform may be a demo or early-stage project; maturity and reliability are unclear
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/transactions/308/receipt
- —All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access on the Base networkhttps://lowpaymentfee.com
- —The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com
- —Documentation pages (/docs, /pricing, /api, /README) render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs