{"id":"8bc5df76-ad8f-4de2-bebd-2d7b852d039b","shortId":"GSHMZs","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 66) 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 pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/crypto data feeds, and utility services — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, this specific endpoint is scoped to retrieving attachments for a particular email resource. No OpenAPI schema, request body documentation, or response examples are available beyond the x402 challenge metadata, so the exact request format and response structure are unknown.\n\nThe endpoint is live and returns a valid x402 challenge (HTTP 402) with version 1 of the protocol. Payment is directed to wallet 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC at contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base. The timeout for payment settlement is 300 seconds.","tags":[],"capabilities":["x402-payment","email-attachments","usdc-base","pay-per-request","json-response"],"categories":["storage","email"],"synonyms":["email attachment API","x402 email endpoint","pay-per-call email","micropayment attachment download","Base USDC API","lowpaymentfee email"],"warnings":["No API documentation available — request body format and response schema are unknown","Endpoint is scoped to a single email ID (66); unclear if other email IDs are accessible","Provider docs, pricing, and README pages return no useful content beyond a wallet-connect prompt","No OpenAPI spec or ai-plugin manifest discovered"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/66/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/66/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 and returns a valid x402 challenge, but there is no OpenAPI schema, no request/response documentation, and no examples. The endpoint path suggests a very narrow resource (email 66 attachments) with unclear utility. Docs, pricing, and README pages all render only a wallet-connect prompt with no substantive 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'000':73 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':189 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':194 '1':180 '20':72 '300':203 '402':177 '6':79 '66':37 'Base USDC API' 'accept':44 'access':30 'ai/ml':97 'analysi':100 'analyt':96 'api':93,118 'attach':3,15,33,134 'avail':150 'base':8,20,57,74,196 'behind':38 'beyond':151 'bodi':144 'broader':86 'call':92 'challeng':154,175 'classif':102 'commit':125 'contract':193 'cost':67 'data':95,105 'decim':80 'direct':186 'document':145 'email':2,14,32,35,138 'email attachment API' 'email-attachments' 'embed':103 'endpoint':26,43,129,167 'exact':62,158 'exampl':148 'feed':106 'finance/crypto':104 'format':160 'host':84 'howev':126 'http':176 'id':36 'infer':98 'json':49 'json-response' 'key':119 'limit':122 'live':169 'lowpaymentfee email' 'lowpaymentfee.com':28,83 'maximum':66 'metadata':155 'micropay':6,18 'micropayment attachment download' 'network':58 'openapi':141 'particular':137 'pay':90 'pay-per-cal':89 'pay-per-call email' 'pay-per-request' 'payment':50,184,200 'paywal':41 'per':11,23,70,91,114 'post':45 'price':111 'protocol':183 'provid':29,82 'rate':121 'request':12,24,46,71,115,143,159 'resourc':139 'respons':147,162 'retriev':1,13,133 'return':48,171 'schema':142 'scheme':63 'scope':131 'second':204 'sentiment':99 'servic':109 'settl':52 'settlement':201 'span':94 'specif':34,128 'structur':163 'suit':87 'summar':101 'timeout':198 'unit':75 'unknown':165 'usdc':54,77,191 'usdc-base' 'use':59,190 'util':108 'valid':173 'version':179 'via':4,16 'wallet':188 'x402':5,17,40,61,153,174 'x402 email endpoint' 'x402-payment'","prices":[{"id":"a9b3fb88-5fa7-4465-b541-bb697b2f92f4","listingId":"8bc5df76-ad8f-4de2-bebd-2d7b852d039b","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/66/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":"2026-04-21T18:32:12.546Z"}],"sources":[{"listingId":"8bc5df76-ad8f-4de2-bebd-2d7b852d039b","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/66/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:12.546Z","lastSeenAt":"2026-04-22T01:02:05.251Z"}],"details":{"listingId":"8bc5df76-ad8f-4de2-bebd-2d7b852d039b","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/66/attachments \\\n  -H \"X-PAYMENT: <x402-payment-header>\" \\\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 HTTP 402 with x402 version 1 challenge requiring USDC payment on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/66/attachments"},{"claim":"Max amount required is 20000 base units of USDC (6 decimals) = $0.02","source_url":"https://lowpaymentfee.com/api/v1/emails/66/attachments"},{"claim":"Provider advertises $0.02/request pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/emails/66/attachments"}],"useCases":["Retrieving email attachments programmatically via micropayment","Agent-driven email data extraction without API key management","Paying per-request for on-demand email attachment access"],"bestFor":["AI agents needing on-demand email attachment retrieval","Developers wanting keyless, pay-per-use email data access","Workflows requiring x402-compatible micropayment endpoints"],"notFor":["Bulk email processing or high-volume attachment downloads (no documented batch support)","Users who need detailed API documentation or guaranteed SLAs","Accessing arbitrary email IDs (this endpoint is scoped to email 66)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:20.512Z"},"updatedAt":"2026-04-22T01:02:05.251Z"}}