{"id":"331eeba4-e654-43c9-a70e-6ec9ed6f65f0","shortId":"86x2um","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 29) behind an x402 paywall. Payment is settled in USDC on the Base network at $0.02 per request (20,000 base units with 6 decimals). The endpoint accepts POST requests and returns application/json responses.\n\nThe broader lowpaymentfee.com platform advertises a suite of pay-per-call APIs spanning data analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance/Web3 data (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 commitments required — payment is handled entirely via the x402 protocol using USDC on Base.\n\nThe specific endpoint `/api/v1/emails/29/attachments` appears to serve attachment data for a particular email resource. Documentation beyond the landing page is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no additional technical detail. There is no OpenAPI spec, no request/response schema documentation, and no usage examples available. The endpoint is confirmed live (returns a valid 402 challenge), but the lack of documentation makes it difficult to know what request body to send or what the response structure looks like.","tags":[],"capabilities":["x402-payment","usdc-base","email-attachments","pay-per-request","no-api-key"],"categories":["data","email"],"synonyms":["email attachment API","x402 email endpoint","micropayment email API","Base USDC API","pay-per-call email","lowpaymentfee"],"warnings":["No API documentation available — docs, pricing, and README pages only show 'Connect wallet'","No OpenAPI or request/response schema provided","The endpoint path references a specific email ID (29), suggesting it may be a demo or placeholder rather than a general-purpose API","Purpose and expected request body for this email attachments endpoint are unknown"],"endpointUrl":"https://lowpaymentfee.com/api/v1/emails/29/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/29/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 402 challenge, confirming pricing and payment details. However, there is no OpenAPI spec, no request/response schema, no documentation beyond a wallet-connect prompt, and no examples. The purpose of this specific email-attachments endpoint is unclear and may be a demo or placeholder. Effectively a stub 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'0.02':10,22,52,116 '000':56 '20':55 '29':37 '402':205 '6':60 'Base USDC API' 'accept':64 'access':30 'addit':180 'advertis':75 'ai/ml':87 'analysi':90 'analyt':86 'api':83,121,166 'appear':146 'application/json':69 'attach':3,15,33,149 'avail':196 'base':8,20,49,57,141 'behind':38 'beyond':157 'bodi':219 'broader':72 'call':82 'challeng':206 'classif':92 'commit':128 'confirm':200 'connect':175 'convers':109 'data':85,95,150 'decim':61 'detail':182 'difficult':214 'doc':165 'document':156,191,211 'email':2,14,32,35,154 'email attachment API' 'email-attachments' 'embed':93 'endpoint':26,63,112,144,198 'entir':133 'estim':103 'exampl':195 'exchang':98 'extrem':162 'feed':97 'finance/web3':94 'gas':102 'generat':110 'geocod':107 'handl':132 'id':36 'infer':88 'infrastructur':105 'key':122 'know':216 'lack':209 'land':159 'like':228 'limit':125 'live':201 'look':227 'lowpaymentfee' 'lowpaymentfee.com':28,73 'make':212 'micropay':6,18 'micropayment email API' 'network':50 'no-api-key' 'openapi':186 'page':160,170 'particular':153 'pay':80 'pay-per-cal':79 'pay-per-call email' 'pay-per-request' 'payment':42,130 'paywal':41 'per':11,23,53,81,117 'platform':74 'post':65 'price':96,114,167 'prompt':177 'protocol':137 'provid':29 'quot':101 'rate':99,124 'readm':169 'render':172 'request':12,24,54,66,118,218 'request/response':189 'requir':129 'resourc':155 'respons':70,225 'retriev':1,13 'return':68,202 'schema':190 'send':221 'sentiment':89 'serv':148 'settl':44 'span':84 'spars':163 'spec':187 'specif':34,143 'structur':226 'suit':77 'summar':91 'technic':181 'token':100 'unit':58 'usag':194 'usdc':46,139 'usdc-base' 'use':138 'util':106 'valid':108,204 'via':4,16,134 'wallet':176 'x402':5,17,40,136 'x402 email endpoint' 'x402-payment'","prices":[{"id":"5359dd6d-ba30-4fa8-a1f6-862ad09c3663","listingId":"331eeba4-e654-43c9-a70e-6ec9ed6f65f0","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/29/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":"2026-04-21T18:32:10.803Z"}],"sources":[{"listingId":"331eeba4-e654-43c9-a70e-6ec9ed6f65f0","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/emails/29/attachments","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:10.803Z","lastSeenAt":"2026-04-22T11:32:42.715Z"}],"details":{"listingId":"331eeba4-e654-43c9-a70e-6ec9ed6f65f0","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/emails/29/attachments \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-header>\"","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"Endpoint returns a valid x402 402 challenge with maxAmountRequired of 20000 in USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/emails/29/attachments"},{"claim":"All endpoints 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":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/emails/29/attachments"},{"claim":"Docs, API, pricing, and README pages render only a 'Connect wallet' prompt","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Retrieving email attachments programmatically via micropayment","Integrating email data access into agent workflows without API key management","Paying per-request for on-demand email attachment retrieval"],"bestFor":["Agents needing one-off email attachment access without subscription","Developers exploring x402 micropayment-gated APIs","Workflows requiring keyless, pay-as-you-go data access"],"notFor":["Bulk email processing requiring high throughput at low marginal cost","Users who need detailed API documentation and schema guarantees before integration","Non-crypto users who cannot settle payments in USDC on Base"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:21.725Z"},"updatedAt":"2026-04-22T11:32:42.715Z"}}