Pay-per-call API key access on Base via x402 — $0.02 per request in USDC.
What it does
lowpaymentfee.com is an x402-enabled API platform that sells access to a variety of endpoints across data & analytics, AI & machine learning, finance & Web3, and infrastructure/utility categories. Each request costs $0.02 in USDC on the Base network, settled on-chain with no API keys, no rate limits, and no commitments required.
The specific endpoint at `/api/v1/apikeys/87` is labeled "Premium API Access" and returns a valid x402 challenge (HTTP 402) requesting payment of 20,000 base units of USDC (0x8335…2913 on Base, 6 decimals = $0.02) via the "exact" scheme. The payment is directed to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. The endpoint accepts POST requests.
The broader platform advertises additional endpoints including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and generation — all at the same $0.02/request price point. However, documentation is extremely thin: the docs, API, pricing, and README pages all render only a "Connect wallet" prompt with no further technical detail, schemas, or usage examples. Without request/response schemas or concrete documentation for any of these endpoints, it is unclear what inputs they accept or what outputs they return.
Capabilities
Use cases
- —Agents purchasing one-off API access without needing pre-provisioned keys
- —On-chain pay-per-request access to analytics, AI, or finance endpoints
- —Programmatic access to utility services (geocoding, validation, conversion) with crypto payment
Fit
Best for
- —Developers or agents wanting zero-commitment, pay-as-you-go API access
- —Use cases requiring on-chain payment settlement on Base
- —Quick, low-cost API calls without account registration
Not for
- —Users needing detailed API documentation or guaranteed SLAs
- —High-volume use cases where $0.02/request adds up significantly
- —Users who cannot transact in USDC on the Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/apikeys/87 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-header>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge with clear pricing, but there is virtually no documentation — docs, API, pricing, and README pages all show only 'Connect wallet'. No request/response schemas, no usage examples, and no explanation of what 'Premium API Access' actually returns. This is effectively a stub listing.
Warnings
- —No API documentation available — all doc pages render only 'Connect wallet'
- —No request or response schema provided for this endpoint or any other listed endpoint
- —Purpose of '/api/v1/apikeys/87' ('Premium API Access') is ambiguous — it may provision an API key rather than serve data directly
- —No OpenAPI spec or ai-plugin manifest found
Citations
- —Endpoint returns HTTP 402 with x402 challenge requesting 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/apikeys/87
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/apikeys/87
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Available API categories include Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructurehttps://lowpaymentfee.com
- —Docs, API, pricing, and README pages all show only 'Connect wallet'https://lowpaymentfee.com/docs