{"id":"61b514a3-43f4-4e6a-bc54-03c9ed129a77","shortId":"yVT28J","kind":"x402","title":"x402-gated email endpoint on Base, pay $0.02 per request in USDC with no API keys.","tagline":"x402-gated email endpoint on Base, pay $0.02 per request in USDC with no API keys.","description":"This endpoint at lowpaymentfee.com provides premium API access via the x402 payment protocol. The specific resource `/api/v1/emails/16` appears to be part of a broader platform offering dozens of pay-per-call endpoints spanning data analytics, AI/ML inference, finance, crypto, and utility services — all gated behind x402 micropayments on the Base network.\n\nPayment is settled in USDC (contract 0x8335…2913 on Base) using the \"exact\" scheme. The x402 challenge advertises a maxAmountRequired of 20,000 base units, which at 6 decimals for USDC equals $0.02 per request. The platform advertises no API keys, no rate limits, and instant access — callers simply attach an X-PAYMENT header with a valid x402 payment proof.\n\nThe specific functionality of the `/api/v1/emails/16` resource is not documented in the crawled material. The landing page lists categories like Data & Analytics, AI & ML, Finance & Web3, and Infrastructure utilities, but does not enumerate an \"emails\" category. The endpoint accepts POST requests and returns application/json. Without further documentation or example responses, the exact data returned by this email-related endpoint remains unclear.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","email-data","json-response","no-api-key","micropayment"],"categories":["data","email"],"synonyms":["email API","premium email endpoint","x402 email","lowpaymentfee email","pay-per-call email","Base USDC API","micropayment email"],"warnings":["The /api/v1/emails/16 endpoint is not listed on the provider's landing page among its advertised APIs — its purpose is unclear.","Documentation pages (/docs, /pricing, /README) returned no useful content, only a 'Connect wallet' prompt.","No OpenAPI spec, no request/response examples, and no description of what the emails endpoint returns.","The endpoint path includes a numeric ID (16), suggesting it may reference a specific record rather than a general-purpose API."],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/16","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/16","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live (402 challenge captured) and pricing is clear ($0.02 USDC on Base). However, the specific /emails/16 resource is not documented anywhere in the crawl material, there is no OpenAPI schema, no example request/response, and the docs/pricing/README pages all returned only a 'Connect wallet' stub. The actual functionality is 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'0.02':9,26,119 '000':109 '0x8335':93 '20':108 '2913':94 '6':114 'Base USDC API' 'accept':186 'access':42,133 'advertis':104,124 'ai':170 'ai/ml':71 'analyt':70,169 'api':16,33,41,126 'appear':52 'application/json':191 'attach':136 'base':7,24,85,96,110 'behind':80 'broader':58 'call':66 'caller':134 'categori':166,183 'challeng':103 'contract':92 'crawl':160 'crypto':74 'data':69,168,200 'decim':115 'document':157,194 'dozen':61 'email':4,21,182,205 'email API' 'email-data' 'email-rel':204 'endpoint':5,22,36,67,185,207 'enumer':180 'equal':118 'exact':99,199 'exampl':196 'financ':73,172 'function':150 'gate':3,20,79 'header':141 'infer':72 'infrastructur':175 'instant':132 'json-response' 'key':17,34,127 'land':163 'like':167 'limit':130 'list':165 'lowpaymentfee email' 'lowpaymentfee.com':38 'materi':161 'maxamountrequir':106 'micropay':82 'micropayment' 'micropayment email' 'ml':171 'network':86 'no-api-key' 'offer':60 'page':164 'part':55 'pay':8,25,64 'pay-per-cal':63 'pay-per-call email' 'pay-per-request' 'payment':46,87,140,146 'per':10,27,65,120 'platform':59,123 'post':187 'premium':40 'premium email endpoint' 'proof':147 'protocol':47 'provid':39 'rate':129 'relat':206 'remain':208 'request':11,28,121,188 'resourc':50,154 'respons':197 'return':190,201 'scheme':100 'servic':77 'settl':89 'simpli':135 'span':68 'specif':49,149 'unclear':209 'unit':111 'usdc':13,30,91,117 'usdc-base' 'use':97 'util':76,176 'valid':144 'via':43 'web3':173 'without':192 'x':139 'x-payment':138 'x402':2,19,45,81,102,145 'x402 email' 'x402-gated':1,18 'x402-payment'","prices":[{"id":"2a742cb0-67a2-496d-a8af-1fd76768d406","listingId":"61b514a3-43f4-4e6a-bc54-03c9ed129a77","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/16","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:10.856Z"}],"sources":[{"listingId":"61b514a3-43f4-4e6a-bc54-03c9ed129a77","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/16","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.856Z","lastSeenAt":"2026-04-22T11:32:42.746Z"}],"details":{"listingId":"61b514a3-43f4-4e6a-bc54-03c9ed129a77","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/16 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-proof>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The platform advertises $0.02 per request with no API keys, no rate limits, and instant access on the Base network.","source_url":"https://lowpaymentfee.com"},{"claim":"The x402 challenge specifies maxAmountRequired of 20000 base units in USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base.","source_url":"https://lowpaymentfee.com/api/v1/emails/16"},{"claim":"The landing page lists Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories but does not list an emails category.","source_url":"https://lowpaymentfee.com"}],"useCases":["Retrieving email-related data or records via a single paid API call","Integrating low-cost email data lookups into agent workflows","Programmatic access to email resources without managing API keys or subscriptions"],"bestFor":["Agents needing on-demand email data with no subscription overhead","Developers who want to pay per call in USDC on Base","Low-volume or sporadic usage patterns where flat-rate plans are wasteful"],"notFor":["High-volume email sending or transactional email delivery","Users who need detailed documentation or SLA guarantees before integrating","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.706Z"},"updatedAt":"2026-04-22T11:32:42.746Z"}}