{"id":"45082c23-62e2-4b43-884d-ac6215fef972","shortId":"ar4yKE","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 email ID 9) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled in USDC on the Base network at $0.02 per call (maxAmountRequired of 20,000 base units with 6 decimals = $0.02), with no API keys, rate limits, or subscriptions required.\n\nThe provider lowpaymentfee.com hosts a broader suite of x402-gated APIs spanning data & analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced uniformly at $0.02 per request and settle on the Base network using USDC.\n\nDocumentation is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The specific purpose and data format of the email attachments endpoint is unclear beyond the generic \"Premium API Access\" label. The endpoint is confirmed live via a valid x402 challenge response.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","per-request-micropayment","no-api-key"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email endpoint","micropayment email access","Base USDC API","pay-per-request email","lowpaymentfee API"],"warnings":["No API documentation available — docs, pricing, and README pages only show 'Connect wallet'","No OpenAPI or request/response schema provided","The specific purpose and data format of /api/v1/emails/9/attachments is unclear","The endpoint path references a hardcoded email ID (9), suggesting it may be a demo or placeholder"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/9/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/9/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.250","qualityRationale":"The endpoint is confirmed live via a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the purpose of this specific email attachments endpoint is opaque. This is effectively a stub 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'000':66 '20':65 '6':70 '9':37 'Base USDC API' 'accept':44 'access':30,193 'ai/ml':97 'analysi':100 'analyt':96 'api':75,93,144,192 'attach':3,15,33,184 'avail':174 'base':8,20,57,67,134 'behind':38 'beyond':188 'broader':87 'call':62 'challeng':204 'classif':102 'confirm':198 'connect':153 'convers':119 'data':95,179 'decim':71 'detail':160 'doc':143 'document':138,169 'email':2,14,32,35,183 'email attachment API' 'email-attachments' 'embed':103 'endpoint':26,43,122,185,196 'estim':113 'exampl':173 'exchang':108 'extrem':140 'feed':107 'financ':104 'format':180 'gas':112 'gate':92 'generat':120 'generic':190 'geocod':117 'host':85 'id':36 'infer':98 'infrastructur':115 'json':49 'key':76 'label':194 'limit':78 'live':199 'lowpaymentfee API' 'lowpaymentfee.com':28,84 'maxamountrequir':63 'micropay':6,18 'micropayment email access' 'network':58,135 'no-api-key' 'openapi':164 'page':148 'pay-per-request email' 'payment':50 'paywal':41 'per':11,23,61,128 'per-request-micropayment' 'post':45 'premium':191 'price':106,124,145 'prompt':155 'provid':29,83 'purpos':177 'quot':111 'rate':77,109 'readm':147 'render':150 'request':12,24,46,129 'request/response':167 'requir':81 'respons':205 'retriev':1,13 'return':48 'schema':168 'sentiment':99 'settl':52,131 'span':94 'spars':141 'spec':165 'specif':34,176 'subscript':80 'suit':88 'summar':101 'technic':159 'token':110 'unclear':187 'uniform':125 'unit':68 'usag':172 'usdc':54,137 'usdc-base' 'use':136 'util':116 'valid':118,202 'via':4,16,200 'wallet':154 'web3':105 'x402':5,17,40,91,203 'x402 email endpoint' 'x402-gated':90 'x402-payment'","prices":[{"id":"ab22cdbe-8e26-40ea-bffa-b865e58e638c","listingId":"45082c23-62e2-4b43-884d-ac6215fef972","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/9/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":"2026-04-21T18:32:12.979Z"}],"sources":[{"listingId":"45082c23-62e2-4b43-884d-ac6215fef972","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/9/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:12.979Z","lastSeenAt":"2026-04-22T01:02:05.793Z"}],"details":{"listingId":"45082c23-62e2-4b43-884d-ac6215fef972","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/9/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":"Endpoint returns a valid x402 challenge with maxAmountRequired of 20000 in USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/9/attachments"},{"claim":"All endpoints priced at $0.02 per request with no API keys, no rate limits, 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/9/attachments"}],"useCases":["Retrieving email attachments programmatically with per-call payment","Agent-driven workflows that need to fetch email data without managing API keys","Integrating email attachment retrieval into automated pipelines using crypto micropayments"],"bestFor":["Agents or bots that need one-off email attachment retrieval without subscription overhead","Developers experimenting with x402 payment-gated APIs on Base","Low-volume, pay-as-you-go access to email data"],"notFor":["High-volume email processing where per-request fees add up quickly","Users who need detailed API documentation or guaranteed SLAs","Non-crypto users who cannot settle payments in USDC on Base"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:20.004Z"},"updatedAt":"2026-04-22T01:02:05.793Z"}}