{"id":"1aeb98c2-f2f2-4757-98cd-8c145dfacb4e","shortId":"BkUnKP","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 58) 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 hosting site lowpaymentfee.com offers a broad catalog of x402-gated API endpoints spanning data analytics, AI/ML inference, finance, crypto, and utility services — all priced at $0.02 per request. However, this specific endpoint (/api/v1/emails/58/attachments) is not listed on the site's public landing page among the advertised APIs. Its purpose — retrieving attachments for a specific email — is unclear in context; it may be a demo, internal, or niche endpoint. No OpenAPI schema, request/response examples, or detailed documentation were found for this endpoint.\n\nThe endpoint is confirmed live: it returns a valid x402 version-1 challenge with a 402 status code. Payment is directed to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 using USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base. The timeout for payment settlement is 300 seconds.","tags":[],"capabilities":["x402-payment","email-attachments","usdc-base","micropayment","post-json"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email","paid email endpoint","lowpaymentfee email","Base USDC email API","402 email attachments"],"warnings":["Endpoint /api/v1/emails/58/attachments is not listed among the site's publicly advertised APIs — may be a demo or internal endpoint","No documentation, OpenAPI schema, or example request/response bodies are available","The endpoint targets a hardcoded email ID (58); unclear if other email IDs are supported or how to discover them","Crawled docs, API, pricing, and README pages all returned only 'Connect wallet' with no substantive content"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/58/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/58/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 documentation, no OpenAPI schema, no request/response examples, and the endpoint is not listed among the site's advertised APIs. The purpose of retrieving attachments for email ID 58 is opaque. This is effectively a stub 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'/api/v1/emails/58/attachments':116 '0.02':10,22,60,72,109 '000':66 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':188 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':191 '20':65 '300':200 '402':180 '402 email attachments' '58':37 '6':70 'Base USDC email API' 'accept':44 'access':30 'address':187 'advertis':129 'ai/ml':99 'among':127 'analyt':98 'api':75,94,130 'attach':3,15,33,134 'base':8,20,57,67,193 'behind':38 'broad':88 'call':62 'catalog':89 'challeng':177 'code':182 'confirm':168 'context':142 'crypto':102 'data':97 'decim':71 'demo':147 'detail':158 'direct':185 'document':159 'email':2,14,32,35,138 'email attachment API' 'email-attachments' 'endpoint':26,43,95,115,151,164,166 'exampl':156 'financ':101 'found':161 'gate':93 'host':83 'howev':112 'id':36 'infer':100 'intern':148 'json':49 'key':76 'land':125 'limit':78 'list':119 'live':169 'lowpaymentfee email' 'lowpaymentfee.com':28,85 'maxamountrequir':63 'may':144 'micropay':6,18 'micropayment' 'network':58 'nich':150 'offer':86 'openapi':153 'page':126 'paid email endpoint' 'payment':50,183,197 'paywal':41 'per':11,23,61,110 'post':45 'post-json' 'price':107 'provid':29 'public':124 'purpos':132 'rate':77 'request':12,24,46,111 'request/response':155 'requir':81 'retriev':1,13,133 'return':48,171 'schema':154 'second':201 'servic':105 'settl':52 'settlement':198 'site':84,122 'span':96 'specif':34,114,137 'status':181 'subscript':80 'timeout':195 'unclear':140 'unit':68 'usdc':54,190 'usdc-base' 'use':189 'util':104 'valid':173 'version':175 'via':4,16 'x402':5,17,40,92,174 'x402 email' 'x402-gated':91 'x402-payment'","prices":[{"id":"045aafd3-945c-4cdf-88bc-59f1ae3e2ee0","listingId":"1aeb98c2-f2f2-4757-98cd-8c145dfacb4e","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/58/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":"2026-04-21T18:32:12.242Z"}],"sources":[{"listingId":"1aeb98c2-f2f2-4757-98cd-8c145dfacb4e","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/58/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:12.242Z","lastSeenAt":"2026-04-22T02:31:50.431Z"}],"details":{"listingId":"1aeb98c2-f2f2-4757-98cd-8c145dfacb4e","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/58/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":"Endpoint returns a valid x402 version-1 challenge with 402 status, accepting USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/58/attachments"},{"claim":"maxAmountRequired is 20000 base units of USDC (6 decimals) = $0.02","source_url":"https://lowpaymentfee.com/api/v1/emails/58/attachments"},{"claim":"Site advertises $0.02/request pricing with no API keys, no rate limits, instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"Payment address is 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3, USDC asset 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/emails/58/attachments"}],"useCases":["Retrieving attachments from a specific email record via programmatic API call","Demonstrating x402 micropayment flows for content retrieval","Agent-driven document or file retrieval behind a paywall"],"bestFor":["Developers experimenting with x402 payment protocol on Base","Agents that need to fetch email attachments with per-call micropayments","Use cases requiring no-auth, pay-per-use access to email data"],"notFor":["Bulk email processing or mailbox management — this targets a single email ID","Users who need detailed API documentation or guaranteed SLAs"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:20.969Z"},"updatedAt":"2026-04-22T02:31:50.431Z"}}