Pay-per-call email API on Base via x402 — $0.02/request in USDC, no API keys required.
What it does
lowpaymentfee.com hosts a collection of pay-per-request APIs accessible via the x402 payment protocol on the Base network. The specific endpoint `/api/v1/emails/42` is listed under "Premium API Access" and accepts POST requests, settling payments in USDC (contract 0x8335…2913 on Base). Each call costs up to 20,000 base units of USDC, which equals $0.02 (USDC uses 6 decimals). No API keys, subscriptions, or rate limits are advertised — callers simply attach an X-PAYMENT header with a valid x402 payment proof.
The broader platform offers endpoints spanning data & analytics (metrics, reports, data export, insights), AI & ML (sentiment analysis, text summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation), all at the same $0.02/request price point. However, the probed endpoint path `/api/v1/emails/42` does not appear in the site's publicly listed API catalog, so its exact functionality is unclear — it may be an unlisted or legacy email-related resource.
The endpoint is live and returns a proper x402 402 challenge. Documentation beyond the landing page is extremely thin: the /docs, /api, /pricing, and /README pages all render only a "Connect wallet" prompt with no substantive content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available from the crawl.
Capabilities
Use cases
- —Programmatic email data retrieval or operations paid per-call with USDC
- —Agent-driven workflows needing keyless, pay-as-you-go API access
- —Integrating x402-compatible payment flows into automated pipelines
Fit
Best for
- —Developers wanting zero-signup, pay-per-use API access
- —AI agents with x402 payment capability on Base
- —Users who prefer crypto micropayments over subscription billing
Not for
- —Users needing detailed API documentation or OpenAPI specs before integrating
- —High-volume callers who would benefit from bulk pricing or subscriptions
- —Anyone without a Base-network USDC wallet or x402 client
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/emails/42 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but the specific resource (/api/v1/emails/42) is not listed on the site's catalog, there is no OpenAPI spec, no request/response schema, and all documentation pages are empty stubs. The exact functionality of this endpoint cannot be confirmed from available material.
Warnings
- —The endpoint path /api/v1/emails/42 does not appear in the provider's public API listing — its exact purpose is unknown.
- —All documentation pages (/docs, /api, /pricing, /README) returned only 'Connect wallet' with no substantive content.
- —No OpenAPI spec, request schema, or response schema is available — callers cannot know what to send or expect back.
- —The description 'Premium API Access' is generic and does not clarify what this endpoint does.
Citations
- —The site lists APIs at $0.02/request with no API keys, no rate limits, and instant access on the Base network.https://lowpaymentfee.com
- —The x402 challenge specifies maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02.https://lowpaymentfee.com/api/v1/emails/42
- —The endpoint /api/v1/emails/42 is not listed among the publicly advertised APIs on the landing page.https://lowpaymentfee.com