Pay-per-call email API on Base via x402 — $0.02/request in USDC, no API keys required.
What it does
This endpoint at lowpaymentfee.com provides a premium email-related API accessible via the x402 payment protocol. The specific resource `/api/v1/emails/3` accepts POST requests and charges $0.02 per call (20,000 base units of USDC on the Base network, where USDC has 6 decimals). Payment is settled on-chain to a designated wallet address, with no API keys, rate limits, or upfront commitments required.
The endpoint is part of a broader platform (lowpaymentfee.com) that offers dozens of pay-per-call APIs spanning data & analytics, AI/ML inference, finance & Web3 data, and infrastructure utilities — all priced at $0.02 per request. The x402 challenge is live and well-formed, returning a standard 402 response with payment parameters including asset address (USDC on Base), payTo address, and a 300-second payment timeout.
Documentation on the site is extremely sparse — the docs, pricing, API, and README pages all render only a "Connect wallet" prompt with no further content. The exact functionality of the `/api/v1/emails/3` endpoint (e.g., whether it sends emails, validates them, or retrieves email data) is not documented anywhere in the crawled material. The listing title "Premium API Access" is generic and does not clarify the endpoint's purpose. Prospective callers should be aware that they are paying for an endpoint whose behavior is not publicly documented beyond its URL path.
Capabilities
Use cases
- —Programmatic email operations via a single POST call with crypto micropayment
- —Agent-driven workflows needing email functionality without API key provisioning
- —Testing x402 payment protocol integrations with a low-cost endpoint
Fit
Best for
- —Developers experimenting with x402 pay-per-call patterns
- —AI agents that need keyless, on-demand email API access
- —Crypto-native applications on Base that want frictionless API billing
Not for
- —Production email workflows requiring documented SLAs and detailed API specs
- —Users who need free or fiat-billed email services
- —Anyone requiring clear documentation of request/response schemas before calling
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/emails/3 \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-token>" \
-d '{}'Endpoint
Quality
The x402 challenge is live and well-formed, confirming the endpoint exists and accepts payment. However, there is zero documentation on what this endpoint actually does — no request/response schema, no examples, no description beyond a generic title. The docs, pricing, and README pages are all blank. This is effectively a stub listing.
Warnings
- —Endpoint functionality is completely undocumented — the name 'Premium API Access' and path '/api/v1/emails/3' give no clear indication of what the endpoint does or what inputs it expects.
- —All documentation pages (docs, pricing, README, API) return only a 'Connect wallet' prompt with no usable content.
- —No request or response schema is available; callers cannot know what to send or what to expect back.
- —The '/3' suffix in the path is unexplained — it may refer to a specific resource ID, version, or tier.
Citations
- —The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base networkhttps://lowpaymentfee.com/api/v1/emails/3
- —USDC asset address on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913https://lowpaymentfee.com/api/v1/emails/3
- —Platform advertises $0.02/request pricing with no API keys, no rate limits, and instant accesshttps://lowpaymentfee.com
- —Docs, pricing, API, and README pages render only a 'Connect wallet' prompthttps://lowpaymentfee.com/docs