{"id":"10178a0d-3127-423f-abec-8e09c6c9c3bb","shortId":"PfjaNV","kind":"x402","title":"Retrieve email attachments via x402 micropayment on Base (USDC, $0.02/request).","tagline":"Retrieve email attachments via x402 micropayment on Base (USDC, $0.02/request).","description":"This endpoint at lowpaymentfee.com provides access to email attachments (specifically for email ID 25) behind an x402 paywall. It accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) with a maximum cost of 0.02 USDC per request (20,000 base units at 6 decimals).\n\nThe endpoint is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no commitments. However, the specific endpoint listed here (/api/v1/emails/25/attachments) is not documented on the site's landing page among the advertised API categories, so its exact functionality and response schema are unclear.\n\nThe x402 challenge is live and well-formed (version 1, scheme \"exact\", 300-second timeout). No OpenAPI spec, detailed docs, or example responses were found during crawling — the docs, pricing, and API pages all returned only a \"Connect wallet\" prompt with no additional content. Because of this, the actual behavior of the endpoint beyond the payment gate is uncertain.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","micropayment","post-endpoint"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email endpoint","paid email access","Base USDC API","micropayment email","lowpaymentfee email"],"warnings":["This specific endpoint (/api/v1/emails/25/attachments) is not listed among the provider's publicly advertised APIs — its purpose and response format are unverified.","No OpenAPI spec, request schema, or response schema available.","All documentation pages (docs, pricing, API, README) returned only a 'Connect wallet' prompt with no substantive content.","The endpoint path references a hardcoded email ID (25), suggesting it may be a demo or test resource rather than a general-purpose API."],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/25/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/25/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The x402 challenge is live and well-formed, confirming the endpoint exists and accepts payment. However, this specific endpoint (/api/v1/emails/25/attachments) is not listed among the provider's advertised APIs, there is no OpenAPI spec, no documentation beyond a wallet-connect prompt, and no example request/response data. The actual functionality is essentially 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'/request':11,22 '0.02':10,21,64,106 '000':69 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':58 '1':159 '20':68 '25':36 '300':162 '6':73 'Base USDC API' 'accept':42 'access':28 'actual':198 'addit':192 'advertis':137 'ai/ml':96 'among':135 'analyt':95 'api':92,111,138,181 'attach':3,14,31 'base':8,19,53,70 'behavior':199 'behind':37 'beyond':203 'broader':81 'categori':139 'challeng':151 'commit':118 'connect':187 'content':193 'contract':57 'cost':62 'crawl':176 'data':94,99 'decim':74 'detail':168 'doc':169,178 'document':128 'email':2,13,30,34 'email attachment API' 'email-attachments' 'endpoint':24,76,122,202 'exact':142,161 'exampl':171 'finance/web3':98 'form':157 'found':174 'function':143 'gate':91,206 'howev':119 'id':35 'infer':97 'infrastructur':101 'json':47 'key':112 'land':133 'limit':115 'list':123 'live':153 'lowpaymentfee email' 'lowpaymentfee.com':26,83 'maximum':61 'micropay':6,17 'micropayment' 'micropayment email' 'network':54 'offer':85 'openapi':166 'page':134,182 'paid email access' 'part':78 'payment':48,205 'paywal':40 'per':66,107 'platform':82 'post':43 'post-endpoint' 'price':104,179 'prompt':189 'provid':27 'rate':114 'request':44,67,108 'respons':145,172 'retriev':1,12 'return':46,184 'schema':146 'scheme':160 'second':163 'settl':50 'site':131 'span':93 'spec':167 'specif':32,121 'timeout':164 'uncertain':208 'unclear':148 'unit':71 'usdc':9,20,56,65 'usdc-base' 'use':55 'util':102 'varieti':87 'version':158 'via':4,15 'wallet':188 'well':156 'well-form':155 'x402':5,16,39,90,150 'x402 email endpoint' 'x402-gated':89 'x402-payment'","prices":[{"id":"a24e6f3d-4855-4a7c-ae79-39ab4c124e4b","listingId":"10178a0d-3127-423f-abec-8e09c6c9c3bb","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/25/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":"2026-04-21T18:32:10.903Z"}],"sources":[{"listingId":"10178a0d-3127-423f-abec-8e09c6c9c3bb","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/25/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.903Z","lastSeenAt":"2026-04-22T05:31:58.019Z"}],"details":{"listingId":"10178a0d-3127-423f-abec-8e09c6c9c3bb","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/25/attachments \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-token>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The x402 challenge returns maxAmountRequired of 20000 in USDC (6 decimals) on Base, equaling $0.02 per request.","source_url":"https://lowpaymentfee.com/api/v1/emails/25/attachments"},{"claim":"The platform advertises $0.02/request pricing with no API keys, no rate limits, and instant access on Base network.","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base.","source_url":"https://lowpaymentfee.com/api/v1/emails/25/attachments"},{"claim":"The endpoint is not listed among the provider's publicly advertised API categories (Data & Analytics, AI & ML, Finance & Web3, Infrastructure).","source_url":"https://lowpaymentfee.com"}],"useCases":["Programmatically retrieving email attachments behind a per-request paywall","Agent-driven workflows that need to fetch specific email attachment data","Demonstrating x402 micropayment integration on Base network"],"bestFor":["Agents that need on-demand email attachment retrieval without API key management","Developers experimenting with x402 payment protocol on Base","Low-volume, pay-per-use access to email data"],"notFor":["Bulk email processing or high-volume attachment downloads (no documented batch support)","Users who need detailed API documentation or guaranteed SLAs","General-purpose email sending or inbox management"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.609Z"},"updatedAt":"2026-04-22T05:31:58.019Z"}}