{"id":"b20550a5-7871-48cd-8e36-c2d5a9f2d5b3","shortId":"tdqxpL","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 31) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled in USDC on the Base network using the x402 \"exact\" scheme, with a maximum cost of $0.02 per request (20,000 base units of USDC with 6 decimals).\n\nThe provider lowpaymentfee.com hosts a broader suite of x402-gated APIs spanning data & analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all priced at $0.02 per call. No API keys or rate limits are advertised; access is granted instantly upon payment via the x402 protocol.\n\nDocumentation is extremely sparse. The crawled /docs, /api, /pricing, and /README pages all returned only a \"Connect wallet\" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no description of what the attachments endpoint actually returns or what input it expects beyond a POST to the given URL. The specific purpose of \"email 31 attachments\" is unclear — it may be a demo or placeholder resource.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","micropayment","post-endpoint"],"categories":["storage","email"],"synonyms":["email attachment API","x402 email endpoint","paid email access","micropayment email API","Base USDC API","lowpaymentfee"],"warnings":["No API documentation available — all doc pages return only 'Connect wallet'","No OpenAPI or output schema describing request parameters or response format","The specific resource '/api/v1/emails/31/attachments' is unexplained; may be a demo or placeholder","No information on what 'email 31' refers to or what attachments are served"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/31/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/31/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.250","qualityRationale":"The endpoint is live (returns 402 with a valid x402 challenge), but there is no OpenAPI schema, no request/response examples, and no meaningful documentation — every doc page just shows 'Connect wallet'. The specific resource ('emails/31/attachments') is unexplained and may be a demo placeholder. Pricing is clear but everything else must be 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'/docs':150 '/pricing':152 '/readme':154 '0.02':10,22,69,123 '000':73 '20':72 '31':37,202 '6':79 'Base USDC API' 'accept':44 'access':30,134 'actual':183 'advertis':133 'ai/ml':96 'analysi':99 'analyt':95 'api':92,127 'attach':3,15,33,181,203 'base':8,20,57,74 'behind':38 'beyond':190 'broader':86 'call':125 'classif':101 'connect':160 'content':166 'convers':118 'cost':67 'crawl':149 'data':94 'decim':80 'demo':210 'descript':177 'document':144 'email':2,14,32,35,201 'email attachment API' 'email-attachments' 'embed':102 'endpoint':26,43,182 'estim':112 'exact':62 'exampl':174 'exchang':107 'expect':189 'extrem':146 'feed':106 'financ':103 'gas':111 'gate':91 'generat':119 'geocod':116 'given':195 'grant':136 'host':84 'id':36 'infer':97 'infrastructur':114 'input':187 'instant':137 'json':49 'key':128 'limit':131 'lowpaymentfee' 'lowpaymentfee.com':28,83 'maximum':66 'may':207 'micropay':6,18 'micropayment' 'micropayment email API' 'network':58 'openapi':170 'page':155 'paid email access' 'payment':50,139 'paywal':41 'per':11,23,70,124 'placehold':212 'post':45,192 'post-endpoint' 'price':105,121 'prompt':162 'protocol':143 'provid':29,82 'purpos':199 'quot':110 'rate':108,130 'request':12,24,46,71 'request/response':173 'resourc':213 'retriev':1,13 'return':48,157,184 'schema':171 'scheme':63 'sentiment':98 'settl':52 'span':93 'spars':147 'specif':34,198 'suit':87 'summar':100 'token':109 'unclear':205 'unit':75 'upon':138 'url':196 'usdc':54,77 'usdc-base' 'use':59 'util':115 'valid':117 'via':4,16,140 'wallet':161 'web3':104 'x402':5,17,40,61,90,142 'x402 email endpoint' 'x402-gated':89 'x402-payment'","prices":[{"id":"a545b397-aaad-49c6-95b6-67c3c7d60c8a","listingId":"b20550a5-7871-48cd-8e36-c2d5a9f2d5b3","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/31/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":"2026-04-21T18:32:10.875Z"}],"sources":[{"listingId":"b20550a5-7871-48cd-8e36-c2d5a9f2d5b3","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/31/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.875Z","lastSeenAt":"2026-04-22T04:02:23.474Z"}],"details":{"listingId":"b20550a5-7871-48cd-8e36-c2d5a9f2d5b3","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/31/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":"Endpoint returns 402 with x402 challenge accepting USDC on Base network, maxAmountRequired 20000 (=$0.02)","source_url":"https://lowpaymentfee.com/api/v1/emails/31/attachments"},{"claim":"Provider advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"Provider hosts additional API categories: Data & Analytics, AI & ML, Finance & Web3, Infrastructure","source_url":"https://lowpaymentfee.com"}],"useCases":["Retrieving email attachments programmatically via micropayment","Agent-driven document retrieval behind a paywall","Demonstrating x402 protocol integration for email data access"],"bestFor":["Developers experimenting with x402 micropayment protocol","Agents needing pay-per-call access to email attachments without API keys","Testing x402 payment flows on Base network"],"notFor":["Production email management or bulk attachment retrieval (no documented schema or guarantees)","Users needing detailed API documentation or SLA commitments","Free or subscription-based email access"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.648Z"},"updatedAt":"2026-04-22T04:02:23.474Z"}}