{"id":"9d2ef311-185c-48d1-bd96-c53427c3e334","shortId":"7W6Txn","kind":"x402","title":"Pay-per-call email API on Base via x402 — $0.02/request in USDC, no API keys required.","tagline":"Pay-per-call email API on Base via x402 — $0.02/request in USDC, no API keys required.","description":"This endpoint at lowpaymentfee.com provides a premium email-related API accessible via the x402 payment protocol. The specific route `/api/v1/emails/30` 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 specified wallet address using USD Coin (USDC) on Base.\n\nThe 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 platform advertises no API keys, no rate limits, and instant access. However, the specific functionality of the `/api/v1/emails/30` endpoint is not documented in the crawled material; the existing title simply says \"Premium API Access\" and no further schema, input parameters, or response format details are available.\n\nThe endpoint is live and returns a valid x402 402 challenge. The payment scheme is \"exact\" with a max amount of 20,000 USDC base units ($0.02) and a timeout of 300 seconds. Without documentation on what the email endpoint actually does (e.g., send email, validate email, lookup email), users should test with a small payment to discover the response format.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-call","email-api","no-api-key","post-method"],"categories":["email","infrastructure"],"synonyms":["email API","email service","x402 email","pay-per-call email","USDC email endpoint","lowpaymentfee email","Base network API"],"warnings":["No documentation available for the /api/v1/emails/30 endpoint — its actual functionality (send, validate, lookup, etc.) is unknown","All doc pages (docs, api, pricing, README) returned only 'Connect wallet' with no substantive content","No input schema or response schema available; callers must discover behavior empirically","The endpoint path includes '/30' which may be a parameter (e.g., batch size, record ID) but this is unconfirmed"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/30","protocol":"x402","transport":"http","auth":{"type":"x402","details":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","version":"2"},"payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","scheme":"exact","network":"base","mimeType":"application/json","resource":"https://lowpaymentfee.com/api/v1/emails/30","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live and returns a valid x402 challenge, but there is no documentation on what the /api/v1/emails/30 endpoint actually does, what inputs it expects, or what it returns. The crawled docs/pricing/README pages all rendered as just 'Connect wallet' with no useful content. This is effectively a stub 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'/request':12,30 '0.02':11,29,63,130,206 '000':67,202 '20':66,201 '300':211 '402':189 '6':79 'Base network API' 'USDC email endpoint' 'accept':58 'access':48,144,167 'actual':220 'address':91 'advertis':135 'ai/ml':119 'amount':199 'analyt':118 'api':6,16,24,34,47,115,137,166 'avail':179 'base':8,26,68,74,97,204 'broader':104 'call':4,22,65,114 'chain':86 'challeng':190 'charg':62 'coin':94 'crawl':158 'data':117,123 'decim':80 'detail':177 'discov':237 'document':155,214 'dozen':109 'e.g':222 'email':5,23,45,218,224,226,228 'email API' 'email service' 'email-api' 'email-rel':44 'endpoint':38,99,152,181,219 'exact':195 'exist':161 'financ':121 'format':176,240 'function':148 'howev':145 'infer':120 'infrastructur':125 'input':172 'instant':143 'key':17,35,138 'limit':141 'live':183 'lookup':227 'lowpaymentfee email' 'lowpaymentfee.com':40,106 'materi':159 'max':198 'network':75 'no-api-key' 'offer':108 'on-chain':84 'paramet':173 'part':101 'pay':2,20,112 'pay-per-cal':1,19,111 'pay-per-call' 'pay-per-call email' 'payment':52,81,192,235 'per':3,21,64,113,131 'platform':105,134 'post':59 'post-method' 'premium':43,165 'price':128 'protocol':53 'provid':41 'rate':140 'relat':46 'request':60,132 'requir':18,36 'respons':175,239 'return':185 'rout':56 'say':164 'schema':171 'scheme':193 'second':212 'send':223 'settl':83 'simpli':163 'small':234 'span':116 'specif':55,147 'specifi':89 'test':231 'timeout':209 'titl':162 'unit':69,205 'usd':93 'usdc':14,32,71,77,95,203 'usdc-base' 'use':92 'user':229 'util':126 'valid':187,225 'via':9,27,49 'wallet':90 'web3':122 'without':213 'x402':10,28,51,188 'x402 email' 'x402-payment'","prices":[{"id":"52c82311-7415-42ec-b48b-e3972d3dc92a","listingId":"9d2ef311-185c-48d1-bd96-c53427c3e334","amountUsd":null,"unit":"per_call","nativeCurrency":"USD COIN","nativeAmount":"20000","chain":"base","payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","paymentMethod":"x402-usd coin","isPrimary":true,"details":{"scheme":"exact","mime_type":"application/json","accepts_all":[{"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","extra":{"name":"USD Coin","version":"2"},"payTo":"0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3","scheme":"exact","network":"base","mimeType":"application/json","resource":"https://lowpaymentfee.com/api/v1/emails/30","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:11.026Z"}],"sources":[{"listingId":"9d2ef311-185c-48d1-bd96-c53427c3e334","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/30","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:11.026Z","lastSeenAt":"2026-04-22T10:32:39.207Z"}],"details":{"listingId":"9d2ef311-185c-48d1-bd96-c53427c3e334","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/30 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-token>\" \\\n  -d '{}'","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 USDC base units on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/30"},{"claim":"The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/emails/30"}],"useCases":["Programmatic email operations paid per-call without subscription or API key management","Agent-driven workflows that need email functionality with on-chain micropayments","Integrating email capabilities into Web3 or crypto-native applications"],"bestFor":["Developers wanting zero-signup, pay-as-you-go email API access","AI agents that can settle x402 payments on Base","Projects needing low-cost per-request email operations without rate limits"],"notFor":["High-volume email sending where per-call pricing becomes expensive at scale","Users who need detailed API documentation and guaranteed SLAs before integrating","Teams without USDC on Base or x402-compatible payment infrastructure"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.494Z"},"updatedAt":"2026-04-22T10:32:39.207Z"}}