{"id":"c7fb371f-105c-47dc-bba8-567e603760fe","shortId":"XJYbHE","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 13) behind an x402 paywall. The endpoint accepts POST requests and returns JSON. Payment is settled on the Base network using USDC (USD Coin) at a cost of $0.02 per request (20,000 base units with 6 decimals). No API keys or rate limits are required — callers simply include an X-PAYMENT header with a valid x402 payment proof.\n\nThe broader lowpaymentfee.com platform advertises a suite of APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/Web3 data (price feeds, exchange rates, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints share the same $0.02-per-request pricing model and x402 payment protocol on Base. However, this specific listing covers only the `/api/v1/emails/13/attachments` endpoint.\n\nDocumentation on the site 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 example payloads available. The endpoint is confirmed live (returns a proper 402 challenge), but the actual behavior, required request body fields, and response format are unknown.","tags":[],"capabilities":["x402-payment","email-attachments","usdc-base-network","micropayment","post-endpoint","json-response"],"categories":["email","storage"],"synonyms":["email attachment API","x402 email endpoint","paid email access","lowpaymentfee email","Base USDC email API","micropayment email attachments"],"warnings":["No API documentation available — docs, pricing, and README pages all show only 'Connect wallet'","No OpenAPI or JSON schema for request or response bodies","Endpoint path is hardcoded to email ID 13; unclear if other email IDs are accessible","The purpose and content of the email attachments are completely undocumented","No examples of successful responses available"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/13/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/13/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 with a valid 402 challenge and clear pricing ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and the endpoint path suggests a single hardcoded resource (email 13) with no explanation of what it returns. Effectively a stub 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'0.02':10,22,65,136 '000':69 '13':37 '20':68 '402':205 '6':73 'Base USDC email API' 'accept':44 'access':30 'actual':209 'advertis':101 'ai/ml':109 'analysi':112 'analyt':108 'api':76,105,166 'attach':3,15,33 'avail':196 'base':8,20,55,70,147 'behavior':210 'behind':38 'bodi':213 'broader':98 'caller':83 'challeng':206 'classif':114 'coin':60 'confirm':200 'connect':175 'convers':129 'cost':63 'cover':152 'data':107,117 'decim':74 'detail':182 'doc':165 'document':157,191 'email':2,14,32,35 'email attachment API' 'email-attachments' 'embed':115 'endpoint':26,43,132,156,198 'estim':123 'exampl':194 'exchang':120 'extrem':162 'feed':119 'field':214 'finance/web3':116 'format':217 'gas':122 'generat':130 'geocod':127 'header':90 'howev':148 'id':36 'includ':85 'infer':110 'infrastructur':125 'json':49 'json-response' 'key':77 'limit':80 'list':151 'live':201 'lowpaymentfee email' 'lowpaymentfee.com':28,99 'micropay':6,18 'micropayment' 'micropayment email attachments' 'model':141 'network':56 'openapi':186 'page':170 'paid email access' 'payload':195 'payment':50,89,95,144 'paywal':41 'per':11,23,66,138 'per-request':137 'platform':100 'post':45 'post-endpoint' 'price':118,140,167 'prompt':177 'proof':96 'proper':204 'protocol':145 'provid':29 'rate':79,121 'readm':169 'render':172 'request':12,24,46,67,139,212 'request/response':189 'requir':82,211 'respons':216 'retriev':1,13 'return':48,202 'schema':190 'sentiment':111 'settl':52 'share':133 'simpli':84 'site':160 'span':106 'spars':163 'spec':187 'specif':34,150 'suit':103 'summar':113 'technic':181 'unit':71 'unknown':219 'usd':59 'usdc':58 'usdc-base-network' 'use':57 'util':126 'valid':93,128 'via':4,16 'wallet':176 'x':88 'x-payment':87 'x402':5,17,40,94,143 'x402 email endpoint' 'x402-payment'","prices":[{"id":"ba82e3ad-0170-41b3-8c58-515df5c9dfb4","listingId":"c7fb371f-105c-47dc-bba8-567e603760fe","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/13/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":"2026-04-21T18:32:10.241Z"}],"sources":[{"listingId":"c7fb371f-105c-47dc-bba8-567e603760fe","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/13/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.241Z","lastSeenAt":"2026-04-22T05:31:57.319Z"}],"details":{"listingId":"c7fb371f-105c-47dc-bba8-567e603760fe","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/13/attachments \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-proof>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"Endpoint returns 402 with x402 challenge advertising USDC on Base network at maxAmountRequired 20000","source_url":"https://lowpaymentfee.com/api/v1/emails/13/attachments"},{"claim":"Platform advertises $0.02 per request pricing with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"USDC contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/emails/13/attachments"},{"claim":"Docs, API, pricing, and README pages render only 'Connect wallet' with no further content","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Programmatically retrieving email attachments behind a paywall","Agent-driven access to stored email data with per-request micropayments","Integrating email attachment retrieval into automated workflows without API key management"],"bestFor":["Agents needing on-demand email attachment access with no subscription","Developers experimenting with x402 micropayment protocols","Workflows requiring keyless, pay-per-use email data retrieval"],"notFor":["Bulk email processing or high-volume attachment downloads (no documented batch support)","Users needing detailed API documentation or guaranteed SLAs","Accessing arbitrary email IDs (this endpoint is hardcoded to email 13)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:22.486Z"},"updatedAt":"2026-04-22T05:31:57.319Z"}}