x402-gated API collection on Base — pay $0.02 per request in USDC, no keys required.
What it does
lowpaymentfee.com hosts a suite of x402-protocol pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and utility services. Every endpoint costs $0.02 per request, settled in USDC on the Base network. There are no API keys, no rate limits, and no upfront commitments — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The specific endpoint `/api/v1/collections/49` is listed as "Premium API Access" and returns an x402 challenge requesting up to 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. The payment scheme is "exact" with a 300-second timeout. The endpoint accepts POST requests and returns `application/json`.
Documentation 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, and no usage examples available from the crawled material. The site's landing page lists many other endpoints in the same pattern (analytics, AI, finance, infrastructure), all at $0.02 each, but provides no detail on request formats or response payloads for any of them. Prospective users should expect to experiment or contact the provider for integration guidance.
Capabilities
Use cases
- —Accessing premium API data without managing API keys or subscriptions
- —Agent-driven workflows that need on-demand paid API calls settled in USDC
- —Programmatic access to a collection endpoint with per-request crypto payment
Fit
Best for
- —Developers who want zero-signup, pay-as-you-go API access
- —AI agents with x402-compatible wallets on Base
- —Users who prefer crypto micropayments over traditional billing
Not for
- —Users who need detailed API documentation or OpenAPI specs before integrating
- —High-volume consumers who want bulk pricing or subscription discounts
- —Developers without a Base-network USDC wallet
Quick start
# 1. POST to the endpoint — you'll get a 402 challenge:
curl -X POST https://lowpaymentfee.com/api/v1/collections/49
# 2. Parse the 402 JSON to get payment details, sign a payment proof,
# then re-send with the X-PAYMENT header:
curl -X POST https://lowpaymentfee.com/api/v1/collections/49 \
-H "X-PAYMENT: <signed-payment-proof>" \
-H "Content-Type: application/json"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, confirming it works. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a landing page listing, and no examples. The actual functionality behind 'Premium API Access' and 'collections/49' is completely opaque.
Warnings
- —No OpenAPI or schema available — request and response formats are unknown.
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content.
- —The purpose of '/api/v1/collections/49' ('Premium API Access') is vague — it is unclear what data or service it provides.
- —No examples or integration guides found anywhere in the crawled material.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/collections/49
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/collections/49
- —All listed APIs cost $0.02 per request with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —The site lists endpoints across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categorieshttps://lowpaymentfee.com