Pay-per-call API key endpoint on Base via x402 — $0.02 per request in USDC.
What it does
This endpoint at lowpaymentfee.com provides "Premium API Access" via the x402 payment protocol. The specific resource `/api/v1/apikeys/72` appears to be one entry point in a broader platform that offers a variety of pay-per-request APIs spanning data & analytics, AI/ML inference, finance & Web3 data, and infrastructure utilities — all priced at $0.02 per call.
Payment is settled on the Base network using USDC (contract 0x8335…2913) through the x402 "exact" scheme. The endpoint returned a valid 402 challenge with `maxAmountRequired` of 20000 base units, which at 6 decimals equals $0.02 USD. No API keys or subscriptions are required; callers simply attach an X-PAYMENT header with a valid x402 payment proof. The timeout window is 300 seconds.
Documentation is extremely sparse — 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 documentation, and no examples of what the endpoint actually returns when paid. The landing page lists sibling endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, geocoding, and more, but none have documented schemas. The exact purpose of `/api/v1/apikeys/72` (as distinct from the other listed endpoints) is unclear — the name suggests it may provision or return an API key.
Capabilities
Use cases
- —Acquiring API access credentials via a single micropayment
- —Agent-driven pay-per-call API consumption without pre-registration
- —Programmatic access to a multi-category API platform using x402 payments
Fit
Best for
- —Agents needing instant API access without signup or API key management
- —Developers experimenting with x402 payment protocol integrations
- —Low-volume, pay-as-you-go API consumption on Base
Not for
- —High-volume production workloads requiring SLAs or guaranteed uptime
- —Users who need detailed API documentation or response schema guarantees
- —Anyone without a Base-compatible USDC wallet
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/72 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, confirming pricing and payment details. However, documentation is essentially nonexistent — all doc pages show only 'Connect wallet'. There is no OpenAPI spec, no request/response schema, and no examples. The exact function of this specific endpoint (/api/v1/apikeys/72) is ambiguous.
Warnings
- —Documentation pages (/docs, /pricing, /api, /README) all render only 'Connect wallet' with no usable content.
- —No OpenAPI or schema documentation available for any endpoint on the platform.
- —The exact purpose and response format of /api/v1/apikeys/72 is undocumented — the name suggests API key provisioning but this is unconfirmed.
- —Sibling endpoints listed on the landing page (AI, finance, utils) are not verified to be live or functional.
Citations
- —Endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 USDC base units on Base networkhttps://lowpaymentfee.com/api/v1/apikeys/72
- —Platform lists APIs across data/analytics, AI/ML, finance/Web3, and infrastructure categories all at $0.02 per requesthttps://lowpaymentfee.com
- —Pricing is $0.02 per request with no API keys, no rate limits, no minimumshttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/apikeys/72