Pay-per-call API platform on Base (USDC) offering data, AI, finance, and utility endpoints at $0.02/request.
What it does
lowpaymentfee.com is an x402-enabled API platform that hosts a collection of endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and general utility services. Every endpoint is priced at $0.02 per request, settled in USDC on the Base network via the x402 payment protocol. No API keys, accounts, or rate limits are advertised — callers simply attach an x402 payment header to each request.
The specific endpoint at `/api/v1/inbox/108` is listed as "Premium API Access" but its exact functionality is not documented beyond that label. The broader platform advertises endpoints for sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, token quotes, gas estimates, geocoding, validation, conversion, and data generation. All endpoints accept POST requests and return JSON.
The x402 challenge for this endpoint specifies a maxAmountRequired of 20000 base units of USDC (6 decimals), which equals $0.02 per call. Payment is sent to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base. The endpoint is live and returning a valid 402 challenge.
Capabilities
Use cases
- —Agents needing on-demand AI inference (sentiment, summarization, classification) without API key management
- —Fetching real-time crypto token quotes, gas estimates, or exchange rates with per-call payment
- —Geocoding or data validation as a utility microservice in automated pipelines
- —Exporting analytics data or generating insights on a pay-as-you-go basis
Fit
Best for
- —AI agents that need keyless, pay-per-call access to diverse utility endpoints
- —Developers prototyping with low-commitment, no-signup API access
- —Web3-native applications already holding USDC on Base
Not for
- —High-volume production workloads where $0.02/request adds up significantly
- —Users who need detailed SLAs, guaranteed uptime, or enterprise support
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/108 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The endpoint is live and returns a valid x402 402 challenge, but the specific functionality of /api/v1/inbox/108 ('Premium API Access') is entirely undocumented. No OpenAPI schema, no request/response examples, and no description of what this particular inbox endpoint does. The broader site lists many endpoints but provides no detailed docs for any of them. Pricing is clear at $0.02/request.
Warnings
- —The exact purpose and input/output schema of /api/v1/inbox/108 is unknown — 'Premium API Access' is the only description available.
- —No OpenAPI specification, request examples, or response examples are provided for any endpoint on the platform.
- —The /api, /pricing, and /README pages all returned only a 'Connect wallet' prompt with no useful documentation.
- —The platform lists many endpoint categories but none have detailed documentation; actual functionality is unverifiable.
Citations
- —All endpoints are priced at $0.02 per request with no API keys, rate limits, or minimumshttps://lowpaymentfee.com
- —The x402 challenge for /api/v1/inbox/108 specifies maxAmountRequired of 20000 base units of USDC on Basehttps://lowpaymentfee.com/api/v1/inbox/108
- —Platform offers endpoints across data/analytics, AI/ML, finance/Web3, and infrastructure categorieshttps://lowpaymentfee.com
- —USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base networkhttps://lowpaymentfee.com/api/v1/inbox/108