{"id":"81df904e-a512-4867-9772-0197151867f4","shortId":"R2nbQN","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 resource `/api/v1/emails/99` 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 handled inline via the X-PAYMENT header — no API keys, accounts, or rate limits are required.\n\nThe provider operates a broader platform offering dozens of pay-per-call endpoints across categories including data & analytics, AI/ML (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints share the same $0.02/request pricing model and settle on the Base L2 network using USDC.\n\nDocumentation is extremely sparse — the docs, pricing, and API pages all render only a \"Connect wallet\" prompt with no further technical detail. The specific functionality of the `/api/v1/emails/99` endpoint (e.g., what email data it returns or processes, what request body it expects) is not documented anywhere in the crawled material. The endpoint is confirmed live via a valid 402 challenge, but without schema details or example payloads, integration requires experimentation.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-call","email-api","no-api-key","no-rate-limit"],"categories":["email","data"],"synonyms":["email API","premium email endpoint","x402 email","pay-per-request email","Base USDC email API","lowpaymentfee email"],"warnings":["No documentation available — docs, pricing, API, and README pages all render only 'Connect wallet' with no technical content.","The specific purpose and expected input/output of /api/v1/emails/99 is completely undocumented; the name 'Premium API Access' is generic.","No OpenAPI schema, no example requests or responses, no error documentation.","The '/emails/99' path suggests a specific resource ID but its meaning is unclear."],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/99","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/99","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.250","qualityRationale":"The endpoint is confirmed live via a valid 402 challenge, but there is no documentation on what the /api/v1/emails/99 endpoint actually does, what request body it expects, or what it returns. Docs pages are empty. This is effectively a stub 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'/request':12,30,148 '0.02':11,29,63,147 '000':67 '20':66 '402':218 '6':79 'Base USDC email API' 'accept':58 'access':48 'account':94 'across':114 'ai/ml':119 'analysi':121 'analyt':118 'anywher':205 'api':6,16,24,34,47,92,168 'base':8,26,68,74,155 'bodi':199 'broader':104 'call':4,22,65,112 'categori':115 'challeng':219 'charg':62 'classif':123 'confirm':213 'connect':174 'convers':140 'crawl':208 'data':117,192 'decim':80 'detail':181,223 'doc':165 'document':160,204 'dozen':107 'e.g':189 'email':5,23,45,191 'email API' 'email-api' 'email-rel':44 'embed':124 'endpoint':38,113,143,188,211 'estim':134 'exampl':225 'exchang':129 'expect':201 'experiment':229 'extrem':162 'feed':128 'financ':125 'function':184 'gas':133 'generat':141 'geocod':138 'handl':83 'header':90 'includ':116 'infrastructur':136 'inlin':84 'integr':227 'key':17,35,93 'l2':156 'limit':97 'live':214 'lowpaymentfee email' 'lowpaymentfee.com':40 'materi':209 'model':150 'network':75,157 'no-api-key' 'no-rate-limit' 'offer':106 'oper':102 'page':169 'pay':2,20,110 'pay-per-cal':1,19,109 'pay-per-call' 'pay-per-request email' 'payload':226 'payment':52,81,89 'per':3,21,64,111 'platform':105 'post':59 'premium':43 'premium email endpoint' 'price':127,149,166 'process':196 'prompt':176 'protocol':53 'provid':41,101 'quot':132 'rate':96,130 'relat':46 'render':171 'request':60,198 'requir':18,36,99,228 'resourc':56 'return':194 'schema':222 'sentiment':120 'settl':152 'share':144 'spars':163 'specif':55,183 'summar':122 'technic':180 'token':131 'unit':69 'usdc':14,32,71,77,159 'usdc-base' 'use':158 'util':137 'valid':139,217 'via':9,27,49,85,215 'wallet':175 'web3':126 'without':221 'x':88 'x-payment':87 'x402':10,28,51 'x402 email' 'x402-payment'","prices":[{"id":"092d4528-6ef5-4aed-831a-952bdf9d7ed0","listingId":"81df904e-a512-4867-9772-0197151867f4","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/99","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:13.060Z"}],"sources":[{"listingId":"81df904e-a512-4867-9772-0197151867f4","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/99","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:13.060Z","lastSeenAt":"2026-04-22T02:31:51.404Z"}],"details":{"listingId":"81df904e-a512-4867-9772-0197151867f4","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/99 \\\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":"Endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/99"},{"claim":"All endpoints priced at $0.02/request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/emails/99"},{"claim":"Provider offers endpoints across data & analytics, AI/ML, finance & Web3, and infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Accessing email-related data or functionality on a per-call basis without needing an API key","Integrating email services into agent workflows that support x402 micropayments","Programmatic email operations settled instantly on Base L2"],"bestFor":["Developers or agents that already support x402 payment flows","Low-volume or sporadic email API usage where subscription pricing is wasteful","Crypto-native applications on the Base network"],"notFor":["Users who need detailed API documentation before integrating","High-volume email operations where per-call pricing becomes expensive","Users without access to USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:19.875Z"},"updatedAt":"2026-04-22T02:31:51.404Z"}}