{"id":"e37068ca-a4d7-4bc0-955d-e55fc3b8dfa7","shortId":"RUUBqc","kind":"x402","title":"Retrieve email attachments via x402 micropayment on Base for $0.02 per request.","tagline":"Retrieve email attachments via x402 micropayment on Base for $0.02 per request.","description":"This endpoint at lowpaymentfee.com provides access to email attachments (specifically email ID 97) behind an x402 paywall. Payment is settled in USDC on the Base network at $0.02 per request (20,000 base units with 6 decimals). The endpoint accepts POST requests and returns application/json responses.\n\nThe broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance and crypto data (price feeds, exchange rates, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced uniformly at $0.02 per request with no API keys, no rate limits, and no commitments — payment is handled entirely via the x402 protocol using USDC on Base.\n\nDocumentation is extremely sparse. The docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The specific purpose of the /api/v1/emails/97/attachments endpoint is unclear — it is not listed among the advertised APIs on the homepage, and its function (retrieving attachments for a specific email) seems like it may be a demo or placeholder resource rather than a general-purpose API.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","pay-per-request","no-api-key"],"categories":["storage","email"],"synonyms":["email attachment API","x402 email endpoint","micropayment email API","Base USDC API","pay-per-call email","lowpaymentfee"],"warnings":["No documentation available — docs, API, pricing, and README pages all show only 'Connect wallet'","No OpenAPI or schema specification provided","This specific endpoint (/api/v1/emails/97/attachments) is not listed among the advertised APIs on the homepage — may be a demo or placeholder","Request body schema and response format are completely unknown","The endpoint references a hardcoded email ID (97), suggesting it may not be a general-purpose API"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/97/attachments","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/97/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live (returns a valid 402 x402 challenge) and pricing is clear ($0.02 USDC on Base), but there is no documentation, no OpenAPI spec, no request/response examples, and the specific endpoint (/emails/97/attachments) is not listed on the homepage. The docs pages are empty. The endpoint's actual utility is 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'0.02':10,22,52,117 '000':56 '20':55 '6':60 '97':37 'Base USDC API' 'accept':64 'access':30 'advertis':75,194 'ai/ml':87 'among':192 'analysi':90 'analyt':86 'api':83,122,148,195,224 'application/json':69 'attach':3,15,33,203 'avail':178 'base':8,20,49,57,141 'behind':38 'broader':72 'call':82 'classif':92 'commit':129 'connect':157 'convers':109 'crypto':96 'data':85,97 'decim':61 'demo':214 'detail':164 'doc':147 'document':142,173 'email':2,14,32,35,207 'email attachment API' 'email-attachments' 'embed':93 'endpoint':26,63,112,185 'entir':133 'estim':103 'exampl':177 'exchang':100 'extrem':144 'feed':99 'financ':94 'function':201 'gas':102 'general':222 'general-purpos':221 'generat':110 'geocod':107 'handl':132 'homepag':198 'id':36 'infer':88 'infrastructur':105 'key':123 'like':209 'limit':126 'list':191 'lowpaymentfee' 'lowpaymentfee.com':28,73 'may':211 'micropay':6,18 'micropayment email API' 'network':50 'no-api-key' 'openapi':168 'page':152 'pay':80 'pay-per-cal':79 'pay-per-call email' 'pay-per-request' 'payment':42,130 'paywal':41 'per':11,23,53,81,118 'placehold':216 'platform':74 'post':65 'price':98,114,149 'prompt':159 'protocol':137 'provid':29 'purpos':181,223 'rate':101,125 'rather':218 'readm':151 'render':154 'request':12,24,54,66,119 'request/response':171 'resourc':217 'respons':70 'retriev':1,13,202 'return':68 'schema':172 'seem':208 'sentiment':89 'settl':44 'span':84 'spars':145 'spec':169 'specif':34,180,206 'suit':77 'summar':91 'technic':163 'unclear':187 'uniform':115 'unit':58 'usag':176 'usdc':46,139 'usdc-base' 'use':138 'util':106 'valid':108 'via':4,16,134 'wallet':158 'x402':5,17,40,136 'x402 email endpoint' 'x402-payment'","prices":[{"id":"df4c90d9-c65a-465a-909b-abbda717b94b","listingId":"e37068ca-a4d7-4bc0-955d-e55fc3b8dfa7","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/97/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:13.000Z"}],"sources":[{"listingId":"e37068ca-a4d7-4bc0-955d-e55fc3b8dfa7","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/97/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:13.000Z","lastSeenAt":"2026-04-22T01:02:05.817Z"}],"details":{"listingId":"e37068ca-a4d7-4bc0-955d-e55fc3b8dfa7","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/97/attachments \\\n  -H \"X-PAYMENT: <x402_payment_token>\" \\\n  -H \"Content-Type: application/json\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 x402 challenge with maxAmountRequired of 20000 in USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/97/attachments"},{"claim":"All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The platform advertises APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"Docs, API, pricing, and README pages render only a 'Connect wallet' prompt","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Retrieving email attachments programmatically via micropayment","Agent-driven document retrieval from email storage","Demonstrating x402 payment protocol integration"],"bestFor":["Developers experimenting with x402 payment protocol","Agents needing pay-per-call access without API key management","Retrieving specific email attachment data on demand"],"notFor":["Bulk email processing or mailbox management","Users needing well-documented, production-grade email APIs","Anyone requiring free or subscription-based access"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:19.876Z"},"updatedAt":"2026-04-22T01:02:05.817Z"}}