Pay-per-call API platform on Base network — $0.02/request via x402 USDC payments.
What it does
lowpaymentfee.com is an x402-enabled API platform that offers a variety of endpoints across data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. Each request costs $0.02 in USDC on the Base network, settled via the x402 exact-payment scheme with no API keys, rate limits, or subscriptions required.
The specific endpoint at `/api/v1/inbox/27` is listed as "Premium API Access" and accepts POST requests. The x402 challenge confirms it is live, requiring a maximum of 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) per call, paid to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base. The payment timeout is 300 seconds.
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 at the same $0.02 price point. However, no OpenAPI schema, detailed documentation, or example request/response payloads were found during the crawl. The `/api`, `/pricing`, and `/README` pages all returned only a "Connect wallet" prompt with no additional content. The exact functionality behind `/api/v1/inbox/27` ("Premium API Access") is unclear — it may be a generic inbox or message endpoint, but no schema or documentation describes its input or output format.
Capabilities
Use cases
- —Programmatic access to paid API endpoints without requiring API keys or subscriptions
- —Agent-driven workflows that need on-demand paid API calls settled in USDC on Base
- —Exploring x402 payment protocol integrations for micro-transaction APIs
Fit
Best for
- —Developers experimenting with x402 payment-gated APIs
- —Agents that can settle USDC payments on Base L2
- —Use cases requiring keyless, pay-as-you-go API access
Not for
- —Users who need detailed API documentation or guaranteed SLAs before integrating
- —Applications requiring free or fiat-only payment methods
- —Production workloads that depend on well-documented request/response schemas
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/inbox/27 \
-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, confirming pricing and payment details. However, there is no OpenAPI schema, no documentation, no example requests or responses, and the purpose of /api/v1/inbox/27 is entirely undocumented. The crawled pages beyond the homepage returned only 'Connect wallet' with no useful content.
Warnings
- —No OpenAPI or schema documentation available for any endpoint
- —The exact functionality of /api/v1/inbox/27 ('Premium API Access') is undocumented — input/output format unknown
- —All secondary pages (/api, /pricing, /README) returned only 'Connect wallet' with no content
- —No example requests or responses available to verify what the endpoint actually does
- —The platform lists many endpoints on its homepage but none have documented schemas
Citations
- —The endpoint returns a 402 x402 challenge requiring 20000 base units of USDC on Base (= $0.02)https://lowpaymentfee.com/api/v1/inbox/27
- —The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base networkhttps://lowpaymentfee.com
- —USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/inbox/27
- —Payment is sent to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3https://lowpaymentfee.com/api/v1/inbox/27