Retrieve email attachments via x402 micropayment on Base for $0.02 per request.
What it does
This endpoint at lowpaymentfee.com provides access to email attachments (specifically email ID 53) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (USD Coin) at a cost of $0.02 per request (20,000 base units with 6 decimals). No API keys or rate limits are required — callers simply include an X-PAYMENT header with a valid x402 payment proof.
The broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto data feeds, and infrastructure utilities — all priced at $0.02 per request on the Base network. However, this specific endpoint (/api/v1/emails/53/attachments) is not listed on the provider's landing page among the advertised API categories. Its purpose — retrieving attachments for a specific email — is unclear in context, and no documentation, request schema, or response schema is available beyond the x402 challenge itself.
The endpoint is live and returns a well-formed x402 challenge (version 1, scheme "exact"). The payment address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, and the USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base. The maximum timeout for payment settlement is 300 seconds.
Capabilities
Use cases
- —Retrieving email attachments programmatically with per-request micropayments
- —Agent-driven email data retrieval without API key management
- —Accessing email content behind a crypto paywall on Base
Fit
Best for
- —Agents or services that need on-demand email attachment retrieval with no subscription
- —Developers experimenting with x402 payment protocol on Base
- —Workflows requiring keyless, pay-as-you-go API access
Not for
- —Bulk email processing requiring high throughput at lower per-unit cost
- —Users who need detailed API documentation or guaranteed SLAs
- —Non-crypto workflows that cannot settle payments on Base network
Quick start
curl -X POST https://lowpaymentfee.com/api/v1/emails/53/attachments \
-H "Content-Type: application/json" \
-H "X-PAYMENT: <x402-payment-proof>"Endpoint
Quality
The endpoint is live and returns a valid x402 challenge, but there is no documentation, no request/response schema, and the specific endpoint (/api/v1/emails/53/attachments) is not listed among the provider's advertised APIs. The purpose and expected input/output are unclear.
Warnings
- —This specific endpoint (/api/v1/emails/53/attachments) is not listed among the provider's advertised API categories — its purpose is unclear.
- —No request body schema or response schema is documented anywhere.
- —The docs, pricing, API, and README pages all returned only a 'Connect wallet' prompt with no actual content.
- —The endpoint appears to serve a single hardcoded email ID (53); generalizability is unknown.
Citations
- —The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 in USDC on Base networkhttps://lowpaymentfee.com/api/v1/emails/53/attachments
- —The platform advertises $0.02 per 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/emails/53/attachments