{"id":"02875b60-deab-4902-82c0-c57531a0c722","shortId":"xar79W","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 16) 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 broader suite of pay-per-call 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 at $0.02 per request with no API keys, no rate limits, and no minimum commitments. However, this specific endpoint — `/api/v1/emails/16/attachments` — is not listed on the provider's landing page among the advertised APIs, so its exact functionality and response format are unclear.\n\nThe endpoint is live and returns a valid x402 challenge (HTTP 402) when called without payment. No OpenAPI schema, documentation, or example responses are available for this specific resource. The provider's docs, pricing, and API pages all render only a \"Connect wallet\" prompt with no additional technical detail.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","pay-per-request","no-api-key"],"categories":["email","storage"],"synonyms":["email attachment API","fetch email attachments","x402 email endpoint","micropayment email API","Base USDC API"],"warnings":["This specific endpoint (/api/v1/emails/16/attachments) is not listed among the provider's advertised APIs on the landing page — its purpose and response format are unknown.","No documentation, OpenAPI spec, or example responses are available for this endpoint.","All non-landing crawled pages (docs, api, pricing, README) returned only a 'Connect wallet' prompt with no technical content.","Response schema is entirely undocumented; integrators must discover the format empirically."],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/16/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/16/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 OpenAPI schema, no documentation, no example request/response, and this specific endpoint is not listed among the provider's advertised APIs. The crawled docs/pricing/API pages are empty beyond a wallet connect prompt. Effectively a stub 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'0.02':10,22,69,126 '000':73 '16':37 '20':72 '402':178 '6':79 'Base USDC API' 'accept':44 'access':30 'addit':213 'advertis':156 'ai/ml':97 'among':154 'analysi':100 'analyt':96 'api':93,131,157,202 'attach':3,15,33 'avail':191 'base':8,20,57,74 'behind':38 'broader':86 'call':92,180 'challeng':176 'classif':102 'commit':139 'connect':208 'convers':119 'cost':67 'data':95 'decim':80 'detail':215 'doc':199 'document':186 'email':2,14,32,35 'email attachment API' 'email-attachments' 'embed':103 'endpoint':26,43,122,143,168 'estim':113 'exact':62,160 'exampl':188 'exchang':108 'feed':107 'fetch email attachments' 'financ':104 'format':164 'function':161 'gas':112 'generat':120 'geocod':117 'host':84 'howev':140 'http':177 'id':36 'infer':98 'infrastructur':115 'json':49 'key':132 'land':152 'limit':135 'list':147 'live':170 'lowpaymentfee.com':28,83 'maximum':66 'micropay':6,18 'micropayment email API' 'minimum':138 'network':58 'no-api-key' 'openapi':184 'page':153,203 'pay':90 'pay-per-cal':89 'pay-per-request' 'payment':50,182 'paywal':41 'per':11,23,70,91,127 'post':45 'price':106,124,200 'prompt':210 'provid':29,82,150,197 'quot':111 'rate':109,134 'render':205 'request':12,24,46,71,128 'resourc':195 'respons':163,189 'retriev':1,13 'return':48,172 'schema':185 'scheme':63 'sentiment':99 'settl':52 'span':94 'specif':34,142,194 'suit':87 'summar':101 'technic':214 'token':110 'unclear':166 'unit':75 'usdc':54,77 'usdc-base' 'use':59 'util':116 'valid':118,174 'via':4,16 'wallet':209 'web3':105 'without':181 'x402':5,17,40,61,175 'x402 email endpoint' 'x402-payment'","prices":[{"id":"e4e06c5f-e03e-4775-8f06-d813fcccf61e","listingId":"02875b60-deab-4902-82c0-c57531a0c722","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/16/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":"2026-04-21T18:32:10.680Z"}],"sources":[{"listingId":"02875b60-deab-4902-82c0-c57531a0c722","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/16/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.680Z","lastSeenAt":"2026-04-22T04:02:23.297Z"}],"details":{"listingId":"02875b60-deab-4902-82c0-c57531a0c722","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/16/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 valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/16/attachments"},{"claim":"All listed APIs 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 advertises APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"The /api/v1/emails/16/attachments endpoint is not listed among the provider's advertised APIs","source_url":"https://lowpaymentfee.com"}],"useCases":["Retrieving attachments from a specific email record via micropayment","Programmatic access to email attachment data without API key registration","Agent-driven email attachment retrieval settled on Base L2"],"bestFor":["Agents needing one-off email attachment retrieval without signup","Developers experimenting with x402 pay-per-call protocols","Workflows requiring no-auth, no-rate-limit access to email data"],"notFor":["Bulk email processing or mailbox management","Users who need documented response schemas before integrating","Accessing emails other than ID 16 (only this resource path is confirmed)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.923Z"},"updatedAt":"2026-04-22T04:02:23.297Z"}}