{"id":"3f6a937c-a34e-46c0-b89b-924e2ec45794","shortId":"4Q434E","kind":"x402","title":"Pay-per-call portfolio transactions endpoint on Base via x402 (USDC, $0.02/request).","tagline":"Pay-per-call portfolio transactions endpoint on Base via x402 (USDC, $0.02/request).","description":"This x402-enabled endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/31/transactions`. It is part of a broader platform offering data & analytics, AI/ML inference, finance/Web3, and infrastructure utility APIs, all priced at $0.02 per request with no API keys, no rate limits, and no commitments required.\n\nPayment is settled on the Base network using USDC (contract `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The x402 challenge advertises a `maxAmountRequired` of 20000 base units, which at 6 decimals equals $0.02 USD per call. The endpoint uses the \"exact\" payment scheme with a 300-second timeout. 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 this specific endpoint path references a hardcoded portfolio ID (31), it likely returns transaction records for that particular portfolio. Without request/response schema documentation, the exact input parameters and output format are unknown. The platform appears to be a demonstration or early-stage x402 API marketplace with many listed endpoints, but documentation is essentially absent.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","portfolio-transactions","pay-per-call","no-api-key"],"categories":["finance","data"],"synonyms":["portfolio transactions API","x402 finance endpoint","USDC micropayment API","Base network API","pay-per-request transactions","lowpaymentfee API"],"warnings":["No API documentation available — docs, pricing, and README pages all show only 'Connect wallet' with no content","No request or response schema provided; input parameters and output format are unknown","Endpoint path is hardcoded to portfolio ID 31; unclear if other portfolio IDs are accessible","Platform appears early-stage or demonstrative; no SLA or reliability guarantees documented"],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/31/transactions","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/portfolios/31/transactions","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is live and returns a valid x402 challenge with clear pricing, but there is no OpenAPI schema, no request/response documentation, and all doc pages return only a wallet-connect prompt. The endpoint path is hardcoded to a single portfolio ID with no explanation of what data it 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'/request':14,28 '0.02':13,27,68,108 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':92 '20000':100 '300':121 '31':165 '6':105 'Base network API' 'USDC micropayment API' 'absent':210 'access':37 'advertis':96 'ai/ml':58 'analyt':57 'api':64,73,139,200 'appear':190 'base':9,23,87,101 'base-network' 'beyond':132 'broader':53 'call':4,18,111 'challeng':95 'commit':80 'connect':148 'content':154 'contract':91 'data':41,56 'decim':106 'demonstr':194 'detail':128 'doc':138 'document':129,178,207 'earli':197 'early-stag':196 'enabl':32 'endpoint':7,21,33,113,158,205 'equal':107 'essenti':209 'exact':116,180 'finance/web3':60 'format':185 'found':131 'hardcod':162 'id':164 'infer':59 'infrastructur':62 'input':181 'key':74 'land':134 'like':167 'limit':77 'list':136,204 'lowpaymentfee API' 'lowpaymentfee.com':35 'mani':203 'marketplac':201 'maxamountrequir':98 'network':88 'no-api-key' 'offer':55 'openapi':125 'output':184 'page':135,143 'paramet':182 'part':50 'particular':173 'path':159 'pay':2,16 'pay-per-cal':1,15 'pay-per-call' 'pay-per-request transactions' 'payment':82,117 'per':3,17,69,110 'platform':54,189 'portfolio':5,19,39,163,174 'portfolio transactions API' 'portfolio-transactions' 'post':44 'price':66,140 'prompt':150 'provid':36 'rate':76 'readm':142 'record':170 'refer':160 'request':45,70 'request/response':176 'requir':81 'return':145,168 'schema':126,177 'scheme':118 'second':122 'settl':84 'specif':157 'stage':198 'substant':153 'timeout':123 'transact':6,20,40,169 'unit':102 'unknown':187 'usd':109 'usdc':12,26,90 'usdc-settlement' 'use':89,114 'util':63 'via':10,24,42 'wallet':149 'without':175 'x402':11,25,31,94,199 'x402 finance endpoint' 'x402-enabled':30 'x402-payment'","prices":[{"id":"082fa1cb-75f5-4826-a490-e58a5303bec1","listingId":"3f6a937c-a34e-46c0-b89b-924e2ec45794","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/portfolios/31/transactions","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:52:42.339Z"}],"sources":[{"listingId":"3f6a937c-a34e-46c0-b89b-924e2ec45794","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/31/transactions","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:52:42.339Z","lastSeenAt":"2026-04-27T22:33:20.725Z"}],"details":{"listingId":"3f6a937c-a34e-46c0-b89b-924e2ec45794","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/31/transactions \\\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 HTTP 402 with x402 challenge advertising maxAmountRequired of 20000 base units in USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/portfolios/31/transactions"},{"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 contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/portfolios/31/transactions"}],"useCases":["Retrieving transaction history for a specific portfolio via micropayment","Integrating pay-per-call portfolio data into agent workflows","Accessing financial transaction data without API key registration"],"bestFor":["Agents needing on-demand portfolio transaction data without signup","Developers experimenting with x402 payment protocol on Base","Low-volume, pay-as-you-go financial data access"],"notFor":["High-volume bulk transaction data retrieval (no documented rate limits but no SLA either)","Users needing detailed API documentation or guaranteed schema stability","Accessing arbitrary portfolio IDs (endpoint is hardcoded to portfolio 31)"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:00.454Z"},"updatedAt":"2026-04-27T22:33:20.725Z"}}