{"id":"42748d24-9840-413c-be5c-cf512279f379","shortId":"VV9BX8","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 for email ID 3) 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 broad suite of pay-per-call 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 minimum commitments. However, this specific endpoint (`/api/v1/emails/3/attachments`) is not listed on the provider's landing page among the advertised API categories, so its exact functionality and response schema are unclear. The endpoint is live and returning a valid x402 402 challenge.\n\nDocumentation beyond the landing page is essentially empty (all doc/pricing/API pages only show a \"Connect wallet\" prompt), so the request body format, expected parameters, and response structure for this endpoint are unknown. Use with caution until more documentation becomes available.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","pay-per-request","json-response"],"categories":["email","storage"],"synonyms":["email attachment API","attachment download","email data retrieval","x402 email endpoint","micropayment email API","lowpaymentfee email"],"warnings":["This specific endpoint (/api/v1/emails/3/attachments) is not listed among the provider's advertised APIs on the landing page.","All documentation pages (docs, pricing, API, README) are empty beyond a 'Connect wallet' prompt — no request/response schemas available.","The endpoint appears hardcoded to email ID 3; generalizability to other email IDs is unknown.","Purpose and content of the 'email attachments' resource is unverified."],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/3/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/3/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 and returns a valid x402 challenge, but there is no documentation, no request/response schema, and the specific endpoint is not listed among the provider's advertised APIs. Effectively a stub 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'0.02':10,22,70,108 '000':74 '20':73 '3':38 '402':159 '6':80 'accept':45 'access':30 'advertis':138 'ai/ml':98 'among':136 'analyt':97 'api':94,113,139 'attach':3,15,33 'attachment download' 'avail':200 'base':8,20,58,75 'becom':199 'behind':39 'beyond':162 'bodi':181 'broad':87 'call':93 'categori':140 'caution':195 'challeng':160 'commit':121 'connect':175 'cost':68 'data':96,101 'decim':81 'doc/pricing/api':170 'document':161,198 'email':2,14,32,36 'email attachment API' 'email data retrieval' 'email-attachments' 'empti':168 'endpoint':26,44,125,151,190 'essenti':167 'exact':63,143 'expect':183 'finance/web3':100 'format':182 'function':144 'host':85 'howev':122 'id':37 'infer':99 'infrastructur':103 'json':50 'json-response' 'key':114 'land':134,164 'limit':117 'list':129 'live':153 'lowpaymentfee email' 'lowpaymentfee.com':28,84 'maximum':67 'micropay':6,18 'micropayment email API' 'minimum':120 'network':59 'page':135,165,171 'paramet':184 'pay':91 'pay-per-cal':90 'pay-per-request' 'payment':51 'paywal':42 'per':11,23,71,92,109 'post':46 'price':106 'prompt':177 'provid':29,83,132 'rate':116 'request':12,24,47,72,110,180 'respons':146,186 'retriev':1,13 'return':49,155 'schema':147 'scheme':64 'settl':53 'show':173 'span':95 'specif':34,124 'structur':187 'suit':88 'unclear':149 'unit':76 'unknown':192 'usdc':55,78 'usdc-base' 'use':60,193 'util':104 'valid':157 'via':4,16 'wallet':176 'x402':5,17,41,62,158 'x402 email endpoint' 'x402-payment'","prices":[{"id":"555146ba-0a7f-4d23-9711-b563f8c6b57b","listingId":"42748d24-9840-413c-be5c-cf512279f379","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/3/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":"2026-04-21T18:32:10.803Z"}],"sources":[{"listingId":"42748d24-9840-413c-be5c-cf512279f379","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/3/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.803Z","lastSeenAt":"2026-04-22T04:02:23.409Z"}],"details":{"listingId":"42748d24-9840-413c-be5c-cf512279f379","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/3/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 endpoint returns a valid x402 402 challenge with USDC on Base, maxAmountRequired 20000 base units","source_url":"https://lowpaymentfee.com/api/v1/emails/3/attachments"},{"claim":"All APIs on lowpaymentfee.com 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":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/3/attachments"}],"useCases":["Programmatically retrieving email attachments behind a paywall","Agent-driven email data extraction with per-call micropayments","Accessing stored email attachment data without API key registration"],"bestFor":["Agents needing on-demand email attachment access with no signup","Developers experimenting with x402 micropayment protocols","Low-volume, pay-as-you-go email data retrieval"],"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 (endpoint is hardcoded to email ID 3)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.784Z"},"updatedAt":"2026-04-22T04:02:23.409Z"}}