{"id":"8f9e6a83-bc12-42db-9974-412f69d85dca","shortId":"aM3cyr","kind":"x402","title":"Retrieve email attachments via x402 micropayment on Base network for $0.02 per request.","tagline":"Retrieve email attachments via x402 micropayment on Base network for $0.02 per request.","description":"This endpoint at lowpaymentfee.com provides access to email attachments through a pay-per-call x402 protocol. Specifically, the route `/api/v1/emails/10/attachments` returns attachment data for email ID 10 when a valid X-PAYMENT header is supplied. Payment is settled in USDC on the Base network at $0.02 per request (20,000 base units with 6 decimals).\n\nThe endpoint is part of a broader platform (lowpaymentfee.com) that offers a variety of x402-gated APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all priced uniformly at $0.02 per request. The platform advertises no API keys, no rate limits, and instant access; the only authentication mechanism is the x402 payment header. No OpenAPI schema or detailed documentation was found beyond the landing page listing; the docs, API, pricing, and README pages all returned only a \"Connect wallet\" prompt with no substantive content.\n\nBecause the specific endpoint path references a hardcoded email ID (`/emails/10/attachments`), it is unclear whether this is a parameterized route (where `10` can be replaced with any email ID) or a fixed demo resource. The response MIME type is `application/json`. The x402 challenge was successfully captured with version 1, confirming the endpoint is live.","tags":[],"capabilities":["x402-payment","email-attachments","usdc-base","pay-per-request","no-api-key"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email","micropayment email","Base USDC email","pay-per-call attachment","lowpaymentfee email"],"warnings":["No OpenAPI or detailed API documentation available — docs/pricing/README pages all return only 'Connect wallet'","Endpoint path contains hardcoded email ID '10'; unclear if parameterized","No request body schema or response schema documented","No example responses available to verify actual output format"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/10/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/10/attachments","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no OpenAPI schema, no request/response examples, and all documentation pages return only a wallet-connect prompt. The endpoint path with a hardcoded email ID is ambiguous. Effectively a stub 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'/emails/10/attachments':181 '0.02':11,24,74,116 '000':78 '1':219 '10':54,192 '20':77 '6':82 'Base USDC email' 'access':32,130 'advertis':121 'ai/ml':105 'analyt':104 'api':101,123,155 'application/json':210 'attach':3,16,35,49 'authent':133 'base':8,21,71,79 'beyond':148 'broader':90 'call':41 'captur':216 'challeng':213 'confirm':220 'connect':164 'content':170 'data':50,103,108 'decim':83 'demo':203 'detail':144 'doc':154 'document':145 'email':2,15,34,52,179,198 'email attachment API' 'email-attachments' 'endpoint':28,85,174,222 'finance/web3':107 'fix':202 'found':147 'gate':100 'hardcod':178 'header':61,139 'id':53,180,199 'infer':106 'infrastructur':110 'instant':129 'key':124 'land':150 'limit':127 'list':152 'live':224 'lowpaymentfee email' 'lowpaymentfee.com':30,92 'mechan':134 'micropay':6,19 'micropayment email' 'mime':207 'network':9,22,72 'no-api-key' 'offer':94 'openapi':141 'page':151,159 'parameter':189 'part':87 'path':175 'pay':39 'pay-per-cal':38 'pay-per-call attachment' 'pay-per-request' 'payment':60,64,138 'per':12,25,40,75,117 'platform':91,120 'price':113,156 'prompt':166 'protocol':43 'provid':31 'rate':126 'readm':158 'refer':176 'replac':195 'request':13,26,76,118 'resourc':204 'respons':206 'retriev':1,14 'return':48,161 'rout':46,190 'schema':142 'settl':66 'span':102 'specif':44,173 'substant':169 'success':215 'suppli':63 'type':208 'unclear':184 'uniform':114 'unit':80 'usdc':68 'usdc-base' 'util':111 'valid':57 'varieti':96 'version':218 'via':4,17 'wallet':165 'whether':185 'x':59 'x-payment':58 'x402':5,18,42,99,137,212 'x402 email' 'x402-gated':98 'x402-payment'","prices":[{"id":"ba4a6d39-2c16-4045-afe9-79799374d38a","listingId":"8f9e6a83-bc12-42db-9974-412f69d85dca","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/10/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":"2026-04-21T18:32:10.557Z"}],"sources":[{"listingId":"8f9e6a83-bc12-42db-9974-412f69d85dca","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/10/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.557Z","lastSeenAt":"2026-04-22T04:02:23.156Z"}],"details":{"listingId":"8f9e6a83-bc12-42db-9974-412f69d85dca","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/10/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 x402 challenge with maxAmountRequired 20000 in USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/emails/10/attachments"},{"claim":"Platform 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 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/10/attachments"}],"useCases":["Retrieving email attachments programmatically without traditional API key signup","Agent-driven workflows that need to fetch email attachment data on demand","Integrating email attachment retrieval into crypto-native applications on Base"],"bestFor":["Developers wanting keyless, pay-per-use email attachment access","AI agents that can settle x402 payments autonomously","Quick prototyping without account registration or rate-limit concerns"],"notFor":["Bulk email processing requiring thousands of requests at low latency (no documented batch support)","Users who need detailed API documentation or OpenAPI specs before integrating","Non-crypto workflows that cannot produce x402 payment headers"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:22.064Z"},"updatedAt":"2026-04-22T04:02:23.156Z"}}