{"id":"5f0e9ba7-0117-4274-ac3c-41ff6a48904c","shortId":"jm2BT5","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 email ID 91) behind an x402 paywall. It accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (contract 0x8335…2913) with a maximum cost of 20,000 base units, which equals $0.02 per request (USDC uses 6 decimals).\n\nThe provider lowpaymentfee.com hosts a broader suite of x402-gated APIs spanning data & analytics, AI/ML inference (sentiment, summarization, classification, embeddings), finance/Web3 (price feeds, exchange rates, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all priced at $0.02 per request with no API keys, no rate limits, and no minimum commitments. However, this specific endpoint is scoped to email attachment retrieval for email ID 91.\n\nDocumentation is extremely sparse. The crawled /docs, /api, /pricing, and /README pages all returned only a \"Connect wallet\" prompt with no further content. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is confirmed live (402 challenge captured), but the actual behavior, required POST body fields, and response structure are unknown.","tags":[],"capabilities":["x402-payment","email-attachment-retrieval","usdc-base-network","micropayment","per-request-billing"],"categories":["email","storage"],"synonyms":["email attachments API","x402 email endpoint","paid email access","Base USDC micropayment API","lowpaymentfee email"],"warnings":["No API documentation available — /docs, /api, /pricing, and /README all return only a wallet-connect prompt","No OpenAPI or schema describing request body or response format","Endpoint path references a specific email ID (91); unclear if this is a demo or production resource","The existing title 'Premium API Access' is generic and does not describe the actual endpoint function"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/91/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/91/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 USDC on Base), but there is no documentation, no OpenAPI spec, no request/response schema, and no examples. The endpoint path is oddly specific (email ID 91 hardcoded). Effectively a stub 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'/docs':149 '/pricing':151 '/readme':153 '/request':11,22 '0.02':10,21,70,115 '000':65 '0x8335':57 '20':64 '2913':58 '402':185 '6':75 '91':35,142 'Base USDC micropayment API' 'accept':41 'access':28 'actual':190 'ai/ml':92 'analyt':91 'api':88,120 'attach':3,14,31,137 'avail':179 'base':8,19,52,66 'behavior':191 'behind':36 'bodi':194 'broader':82 'captur':187 'challeng':186 'classif':96 'commit':128 'confirm':183 'connect':159 'content':165 'contract':56 'convers':110 'cost':62 'crawl':148 'data':90 'decim':76 'document':143,174 'email':2,13,30,33,136,140 'email attachments API' 'email-attachment-retrieval' 'embed':97 'endpoint':24,132,181 'equal':69 'estim':104 'exampl':178 'exchang':101 'extrem':145 'feed':100 'field':195 'finance/web3':98 'gas':103 'gate':87 'generat':111 'geocod':108 'host':80 'howev':129 'id':34,141 'infer':93 'infrastructur':106 'json':46 'key':121 'limit':124 'live':184 'lowpaymentfee email' 'lowpaymentfee.com':26,79 'maximum':61 'micropay':6,17 'micropayment' 'minimum':127 'network':53 'openapi':169 'page':154 'paid email access' 'payment':47 'paywal':39 'per':71,116 'per-request-billing' 'post':42,193 'price':99,113 'prompt':161 'provid':27,78 'rate':102,123 'request':43,72,117 'request/response':172 'requir':192 'respons':197 'retriev':1,12,138 'return':45,156 'schema':173 'scope':134 'sentiment':94 'settl':49 'span':89 'spars':146 'spec':170 'specif':32,131 'structur':198 'suit':83 'summar':95 'unit':67 'unknown':200 'usag':177 'usdc':9,20,55,73 'usdc-base-network' 'use':54,74 'util':107 'valid':109 'via':4,15 'wallet':160 'x402':5,16,38,86 'x402 email endpoint' 'x402-gated':85 'x402-payment'","prices":[{"id":"75e6bbb6-4c7d-497e-b140-d7e391177910","listingId":"5f0e9ba7-0117-4274-ac3c-41ff6a48904c","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/91/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":"2026-04-21T18:32:13.233Z"}],"sources":[{"listingId":"5f0e9ba7-0117-4274-ac3c-41ff6a48904c","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/91/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:13.233Z","lastSeenAt":"2026-04-22T01:02:06.123Z"}],"details":{"listingId":"5f0e9ba7-0117-4274-ac3c-41ff6a48904c","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/91/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 402 challenge with x402Version 1, accepting USDC on Base with maxAmountRequired of 20000 base units","source_url":"https://lowpaymentfee.com/api/v1/emails/91/attachments"},{"claim":"USDC asset contract is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/91/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":"The provider offers APIs across data/analytics, AI/ML, finance/Web3, and infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Retrieving email attachments programmatically via micropayment","Agent-driven email data access without API keys","Pay-per-use email attachment download"],"bestFor":["Agents needing on-demand email attachment access without subscription","Developers experimenting with x402 payment protocol","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","General-purpose email sending or inbox management"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:19.535Z"},"updatedAt":"2026-04-22T01:02:06.123Z"}}