{"id":"1d1a782d-22ac-45ca-983f-ddb04398bc8b","shortId":"ACjFf4","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/1/attachments`. It is part of a broader platform offering dozens of pay-per-call API endpoints across data analytics, AI/ML, finance, infrastructure, and more — all settled on-chain using USDC on the Base network through the x402 protocol.\n\nThe specific endpoint probed here costs $0.02 per request (20,000 base units of USDC with 6 decimals). Payment is handled inline via the X-PAYMENT header; no API keys, accounts, or rate limits are required. The platform advertises a uniform $0.02/request pricing across all its endpoints. The x402 challenge confirms the endpoint is live, accepting the \"exact\" payment scheme with a 300-second timeout, paying to address `0x1A2B...85F3` using USDC (`0x8335...2913`) on Base.\n\nDocumentation is extremely sparse. The docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further 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 a POST method. The endpoint path suggests it retrieves attachments for email ID 1, but the semantics, required body parameters, and response format are entirely unknown from the available material.","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 email API","Base network API","lowpaymentfee email"],"warnings":["No API documentation available — docs, pricing, and README pages all show only 'Connect wallet'","No OpenAPI or request/response schema provided for this endpoint","The endpoint path '/api/v1/emails/1/attachments' has a hardcoded ID '1', suggesting it may be a demo or placeholder","The broader platform lists many endpoint categories but none appear to include email-related APIs, raising questions about this endpoint's purpose"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/1/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/1/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 (402 challenge confirmed) and pricing is clear ($0.02/request in USDC on Base). However, there is no OpenAPI schema, no request/response examples, and all documentation pages render only a wallet-connect prompt. The purpose and behavior of the email attachments endpoint are essentially undocumented, making this a stub 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'/request':122 '0.02':85,121 '000':89 '0x1a2b':149 '0x8335':153 '1':217 '20':88 '2913':154 '300':143 '6':95 '85f3':150 'Base network API' 'USDC email API' 'accept':136 'access':30 'account':110 'across':56,124 'actual':196 'address':148 'advertis':118 'ai/ml':59 'analyt':58 'api':54,108,163 'attach':6,18,33,194,213 'avail':232 'base':11,23,73,90,156 'base-network' 'beyond':203 'bodi':222 'broader':45 'call':53 'chain':68 'challeng':130 'confirm':131 'connect':172 'content':178 'cost':84 'data':57 'decim':96 'descript':189 'doc':162 'document':157 'dozen':48 'email':5,17,32,193,215 'email attachment API' 'email-attachments' 'endpoint':26,55,81,127,133,195,208 'entir':228 'exact':138 'exampl':186 'expect':202 'extrem':159 'financ':60 'format':226 'handl':99 'header':106 'id':216 'infrastructur':61 'inlin':100 'input':200 'key':109 'limit':113 'live':135 'lowpaymentfee email' 'lowpaymentfee.com':28 'materi':233 'method':206 'network':74 'no-api-key' 'offer':47 'on-chain':66 'openapi':182 'page':167 'paramet':223 'part':42 'path':209 'pay':2,14,51,146 'pay-per-cal':50 'pay-per-call email' 'pay-per-request':1,13 'payment':97,105,139 'per':3,15,52,86 'platform':46,117 'post':36,205 'price':123,164 'probe':82 'prompt':174 'protocol':78 'provid':29 'rate':112 'readm':166 'render':169 'request':4,16,37,87 'request/response':185 'requir':115,221 'respons':225 'retriev':7,19,212 'return':197 'schema':183 'scheme':140 'second':144 'semant':220 'settl':65 'spars':160 'specif':80 'suggest':210 'timeout':145 'uniform':120 'unit':91 'unknown':229 'usdc':12,24,70,93,152 'usdc-settlement' 'use':69,151 'via':8,20,34,101 'wallet':173 'x':104 'x-payment':103 'x402':9,21,77,129 'x402 email endpoint' 'x402-payment'","prices":[{"id":"236d5d85-3a72-48d6-b3c4-32443e50a8ce","listingId":"1d1a782d-22ac-45ca-983f-ddb04398bc8b","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/1/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":"2026-04-21T18:32:10.737Z"}],"sources":[{"listingId":"1d1a782d-22ac-45ca-983f-ddb04398bc8b","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/1/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.737Z","lastSeenAt":"2026-04-22T04:02:23.343Z"}],"details":{"listingId":"1d1a782d-22ac-45ca-983f-ddb04398bc8b","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/1/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 with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/1/attachments"},{"claim":"Platform-wide pricing is $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 is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/1/attachments"},{"claim":"Documentation pages render only a 'Connect wallet' prompt with no further content","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Retrieving email attachments programmatically with per-request USDC payment","Agent-driven email data access without pre-registration or API keys","On-chain micropayment-gated document retrieval"],"bestFor":["Agents needing one-off email attachment access without signup","Developers exploring x402 pay-per-call patterns on Base","Scenarios where keyless, on-demand API access is preferred"],"notFor":["Production email workflows requiring documented schemas and SLAs","Bulk email processing where per-request fees add up quickly","Users who need detailed API documentation before integrating"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.94Z"},"updatedAt":"2026-04-22T04:02:23.343Z"}}