{"id":"7c60dd7e-df6c-4407-ad7d-e6c42caf9513","shortId":"CbQqz6","kind":"x402","title":"Pay-per-request email attachment retrieval via x402 on Base (USDC).","tagline":"Pay-per-request email attachment retrieval via x402 on Base (USDC).","description":"This endpoint at lowpaymentfee.com provides access to email attachments via a POST request to `/api/v1/emails/99/attachments`. It is part of a broader platform offering dozens of pay-per-call API endpoints spanning data analytics, AI/ML inference, finance, crypto, and utility services — all settled via the x402 protocol on the Base network using USDC.\n\nThe specific endpoint probed returns a valid x402 challenge (HTTP 402) requesting payment of up to 20,000 base units of USDC (0x8335…2913 on Base). Since USDC uses 6 decimals, this translates to $0.02 per request, consistent with the site's advertised flat pricing of $0.02/request across all endpoints. Payment is made via the x402 \"exact\" scheme to address 0x1A2B…85F3, with a timeout of 300 seconds.\n\nThe platform advertises no API keys, no rate limits, and instant access. However, documentation is extremely thin — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what the email attachments endpoint actually returns or what input it expects beyond an HTTP POST. The endpoint path suggests retrieving attachments for email ID 99, but whether this is a demo resource or a parameterized path is unclear. Treat this listing as a stub until richer documentation is available.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","email-attachments","pay-per-request","no-api-key"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email endpoint","pay-per-call email","USDC API","Base network API","lowpaymentfee","402 payment email"],"warnings":["No OpenAPI or request/response schema available","All documentation pages (docs, API, pricing, README) render only 'Connect wallet' with no content","The endpoint path '/api/v1/emails/99/attachments' uses a hardcoded ID; unclear if parameterized","No description of expected POST body or response format","Platform appears to be a demo or early-stage project with many advertised endpoints but no documentation"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/99/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/99/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 ($0.02 USDC on Base). However, there is no OpenAPI schema, no request/response examples, and all documentation pages are empty beyond a wallet-connect prompt. The purpose of this specific endpoint (email attachments for ID 99) is unclear and 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'/request':125 '0.02':112,124 '000':95 '0x1a2b':139 '0x8335':100 '20':94 '2913':101 '300':145 '402':88 '402 payment email' '6':107 '85f3':140 '99':219 'Base network API' 'USDC API' 'access':30,158 'across':126 'actual':199 'address':138 'advertis':120,149 'ai/ml':59 'analyt':58 'api':54,151,166 'attach':6,18,33,197,215 'avail':243 'base':11,23,74,96,103 'base-network' 'beyond':206 'broader':45 'call':53 'challeng':86 'connect':175 'consist':115 'content':181 'crypto':62 'data':57 'decim':108 'demo':225 'descript':192 'doc':165 'document':160,241 'dozen':48 'email':5,17,32,196,217 'email attachment API' 'email-attachments' 'endpoint':26,55,80,128,198,211 'exact':135 'exampl':189 'expect':205 'extrem':162 'financ':61 'flat':121 'howev':159 'http':87,208 'id':218 'infer':60 'input':203 'instant':157 'key':152 'limit':155 'list':235 'lowpaymentfee' 'lowpaymentfee.com':28 'made':131 'network':75 'no-api-key' 'offer':47 'openapi':185 'page':170 'parameter':229 'part':42 'path':212,230 'pay':2,14,51 'pay-per-cal':50 'pay-per-call email' 'pay-per-request':1,13 'payment':90,129 'per':3,15,52,113 'platform':46,148 'post':36,209 'price':122,167 'probe':81 'prompt':177 'protocol':71 'provid':29 'rate':154 'readm':169 'render':172 'request':4,16,37,89,114 'request/response':188 'resourc':226 'retriev':7,19,214 'return':82,200 'richer':240 'schema':186 'scheme':136 'second':146 'servic':65 'settl':67 'sinc':104 'site':118 'span':56 'specif':79 'stub':238 'substant':180 'suggest':213 'thin':163 'timeout':143 'translat':110 'treat':233 'unclear':232 'unit':97 'usdc':12,24,77,99,105 'usdc-settlement' 'use':76,106 'util':64 'valid':84 'via':8,20,34,68,132 'wallet':176 'whether':221 'x402':9,21,70,85,134 'x402 email endpoint' 'x402-payment'","prices":[{"id":"464aac2c-d271-4d03-aafc-762d0e51b076","listingId":"7c60dd7e-df6c-4407-ad7d-e6c42caf9513","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/99/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":"2026-04-21T18:32:12.782Z"}],"sources":[{"listingId":"7c60dd7e-df6c-4407-ad7d-e6c42caf9513","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/99/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:12.782Z","lastSeenAt":"2026-04-22T01:02:05.566Z"}],"details":{"listingId":"7c60dd7e-df6c-4407-ad7d-e6c42caf9513","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/99/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":"The endpoint returns a 402 challenge requesting up to 20,000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/99/attachments"},{"claim":"USDC asset address is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/99/attachments"},{"claim":"Platform advertises $0.02/request flat pricing with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"Documentation pages render only 'Connect wallet' with no substantive content","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Retrieving email attachments programmatically with per-request USDC payment","Agent-driven workflows that need to fetch email data without API key provisioning","Integrating email attachment access into crypto-native applications"],"bestFor":["Developers wanting keyless, pay-per-use email attachment access","AI agents that can settle x402 payments on Base","Prototyping workflows that need instant API access without signup"],"notFor":["Production email systems requiring documented schemas and SLAs","Users who need bulk email processing at scale (no documented rate limits but no guarantees either)","Non-crypto users who cannot settle USDC payments on Base"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:20.15Z"},"updatedAt":"2026-04-22T01:02:05.566Z"}}