{"id":"4cceb985-1dc8-459a-9668-0de6bf39c03c","shortId":"DsBWrB","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 84) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled in USDC on the Base network at $0.02 per call (maxAmountRequired of 20,000 base units with 6 decimals = $0.02), with no API keys, rate limits, or commitments required.\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 endpoints are priced uniformly at $0.02 per request and settle via 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 schema, no request/response examples, and no description of what the attachments endpoint actually returns or what input it expects. The endpoint is confirmed live (402 challenge captured), but the lack of documentation makes it difficult to use without experimentation.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","micropayment","post-endpoint","json-response"],"categories":["data","email"],"synonyms":["email attachment API","x402 email endpoint","paid email data","lowpaymentfee API","Base USDC micropayment API","email file retrieval"],"warnings":["No OpenAPI or request/response schema available — input format is unknown","All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no content","This endpoint targets a single hardcoded email ID (84); unclear if other email IDs are available","No information on what the attachments response contains or its structure"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/84/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/84/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 with clear pricing, but there is no OpenAPI schema, no request/response examples, and no meaningful documentation beyond a wallet-connect prompt. The specific purpose of this email/attachments endpoint is opaque, and the broader site offers no technical 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'000':66 '20':65 '402':187 '6':70 '84':37 'Base USDC micropayment API' 'accept':44 'access':30 'actual':175 'ai/ml':97 'analysi':100 'analyt':96 'api':75,93,142 'attach':3,15,33,173 'base':8,20,57,67,135 'behind':38 'broader':87 'call':62 'captur':189 'challeng':188 'classif':102 'commit':80 'confirm':185 'connect':151 'convers':119 'data':95 'decim':71 'descript':169 'detail':158 'difficult':197 'doc':141 'document':136,194 'email':2,14,32,35 'email attachment API' 'email file retrieval' 'email-attachments' 'embed':103 'endpoint':26,43,122,174,183 'estim':113 'exampl':166 'exchang':108 'expect':181 'experiment':201 'extrem':138 'feed':107 'financ':104 'gas':112 'gate':92 'generat':120 'geocod':117 'host':85 'id':36 'infer':98 'infrastructur':115 'input':179 'json':49 'json-response' 'key':76 'lack':192 'limit':78 'live':186 'lowpaymentfee API' 'lowpaymentfee.com':28,84 'make':195 'maxamountrequir':63 'micropay':6,18 'micropayment' 'network':58 'openapi':162 'page':146 'paid email data' 'payment':50 'paywal':41 'per':11,23,61,128 'post':45 'post-endpoint' 'price':106,124,143 'prompt':153 'provid':29,83 'quot':111 'rate':77,109 'readm':145 'render':148 'request':12,24,46,129 'request/response':165 'requir':81 'retriev':1,13 'return':48,176 'schema':163 'sentiment':99 'settl':52,131 'span':94 'spars':139 'specif':34 'suit':88 'summar':101 'technic':157 'token':110 'uniform':125 'unit':68 'usdc':54,133 'usdc-base' 'use':199 'util':116 'valid':118 'via':4,16,132 'wallet':152 'web3':105 'without':200 'x402':5,17,40,91 'x402 email endpoint' 'x402-gated':90 'x402-payment'","prices":[{"id":"0cef1508-3868-49fc-8919-d395de36c891","listingId":"4cceb985-1dc8-459a-9668-0de6bf39c03c","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/84/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":"2026-04-21T18:32:13.127Z"}],"sources":[{"listingId":"4cceb985-1dc8-459a-9668-0de6bf39c03c","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/84/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:13.127Z","lastSeenAt":"2026-04-22T02:31:51.471Z"}],"details":{"listingId":"4cceb985-1dc8-459a-9668-0de6bf39c03c","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/84/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":"The endpoint returns a 402 challenge with maxAmountRequired of 20000 in USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/emails/84/attachments"},{"claim":"All endpoints on lowpaymentfee.com are priced at $0.02 per request with no API keys, rate limits, or commitments","source_url":"https://lowpaymentfee.com"},{"claim":"Payment asset is USD Coin (USDC) at contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/84/attachments"}],"useCases":["Retrieving attachments from a specific email record via programmatic API call","Demonstrating x402 micropayment flows on the Base network","Agent-driven email data retrieval with per-request payment"],"bestFor":["Developers experimenting with x402 payment protocol on Base","Agents that need to fetch email attachments without API key management","Low-volume, pay-per-use email data access"],"notFor":["Bulk email processing or high-volume attachment retrieval (no documented batch support)","Users who need detailed API documentation or request/response schemas before integrating","General-purpose email service (this is a single resource endpoint for email ID 84)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:19.663Z"},"updatedAt":"2026-04-22T02:31:51.471Z"}}