{"id":"1a347c93-7803-4e90-b2e8-aa542aa29d2f","shortId":"NRFRKU","kind":"x402","title":"x402-gated portfolio transactions endpoint on Base, paid per-call in USDC.","tagline":"x402-gated portfolio transactions endpoint on Base, paid per-call in USDC.","description":"This endpoint at lowpaymentfee.com provides access to portfolio transaction data via a POST request to `/api/v1/portfolios/55/transactions`. It is part of a broader platform (lowpaymentfee.com) that offers dozens of x402-paywalled API endpoints spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all settled on the Base network using USDC.\n\nThe specific endpoint probed here returns an x402 challenge requesting up to 20,000 base units of USDC (0.02 USD, since USDC uses 6 decimals) per call, paid to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` on Base. The platform advertises a flat $0.02 per request across all endpoints, with no API keys, no rate limits, and no minimum commitments. The payment scheme is \"exact\" with a 300-second timeout.\n\nDocumentation is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no substantive content. There is no OpenAPI schema, no request/response examples, and no description of what fields the transactions endpoint accepts or returns. The endpoint title \"Premium API Access\" and the path suggest it retrieves or creates transactions for a specific portfolio (ID 55), but the exact data model is unknown. The platform appears to be a demonstration or early-stage x402 API marketplace rather than a mature production service.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","portfolio-transactions","per-call-pricing","no-api-key"],"categories":["finance","data"],"synonyms":["portfolio transactions API","x402 paid API","USDC micropayment API","Base network API","pay-per-call API","lowpaymentfee","crypto payment API"],"warnings":["No API documentation available — docs, pricing, and README pages all show only 'Connect wallet'","No OpenAPI or request/response schema provided; input and output formats are unknown","The endpoint path references a hardcoded portfolio ID (55), suggesting it may be a demo or placeholder","The broader platform lists many endpoints but none have documented behavior"],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/55/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/55/transactions","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 no description of what the endpoint actually does beyond its URL path. The docs pages are empty. This is effectively a stub 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'0.02':98,118 '000':93 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':110 '20':92 '300':142 '55':207 '6':103 'Base network API' 'USDC micropayment API' 'accept':184 'access':34,192 'across':121 'address':109 'advertis':115 'ai/ml':65 'analyt':64 'api':60,126,151,191,227 'appear':217 'base':8,22,76,94,112 'base-network' 'broader':50 'call':12,26,106 'challeng':88 'commit':134 'connect':160 'content':166 'creat':200 'crypto payment API' 'data':38,63,68,211 'decim':104 'demonstr':221 'descript':177 'doc':150 'document':145 'dozen':55 'earli':224 'early-stag':223 'endpoint':6,20,30,61,82,123,183,188 'exact':139,210 'exampl':174 'extrem':147 'field':180 'finance/web3':67 'flat':117 'gate':3,17 'id':206 'infer':66 'infrastructur':70 'key':127 'limit':130 'lowpaymentfee' 'lowpaymentfee.com':32,52 'marketplac':228 'matur':232 'minimum':133 'model':212 'network':77 'no-api-key' 'offer':54 'openapi':170 'page':155 'paid':9,23,107 'part':47 'path':195 'pay-per-call API' 'payment':136 'paywal':59 'per':11,25,105,119 'per-cal':10,24 'per-call-pricing' 'platform':51,114,216 'portfolio':4,18,36,205 'portfolio transactions API' 'portfolio-transactions' 'post':41 'premium':190 'price':152 'probe':83 'product':233 'prompt':162 'provid':33 'rate':129 'rather':229 'readm':154 'render':157 'request':42,89,120 'request/response':173 'retriev':198 'return':85,186 'schema':171 'scheme':137 'second':143 'servic':234 'settl':73 'sinc':100 'span':62 'spars':148 'specif':81,204 'stage':225 'substant':165 'suggest':196 'timeout':144 'titl':189 'transact':5,19,37,182,201 'unit':95 'unknown':214 'usd':99 'usdc':14,28,79,97,101 'usdc-settlement' 'use':78,102 'util':71 'via':39 'wallet':161 'x402':2,16,58,87,226 'x402 paid API' 'x402-gated':1,15 'x402-payment' 'x402-paywalled':57","prices":[{"id":"0123188b-a196-42b0-85e3-8506c67c2174","listingId":"1a347c93-7803-4e90-b2e8-aa542aa29d2f","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/55/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":"2026-04-18T18:53:06.144Z"}],"sources":[{"listingId":"1a347c93-7803-4e90-b2e8-aa542aa29d2f","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/55/transactions","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:53:06.144Z","lastSeenAt":"2026-04-27T21:34:10.246Z"}],"details":{"listingId":"1a347c93-7803-4e90-b2e8-aa542aa29d2f","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/55/transactions \\\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":"The endpoint returns an x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/portfolios/55/transactions"},{"claim":"The platform advertises $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/55/transactions"},{"claim":"Docs, API, pricing, and README pages render only a 'Connect wallet' prompt","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Fetching or posting portfolio transaction records behind a micropayment wall","Demonstrating x402 payment protocol integration for API monetization","Programmatic access to financial portfolio data without traditional API keys"],"bestFor":["Developers experimenting with x402 payment protocol","Agents that can settle USDC payments on Base for per-call API access","Use cases needing keyless, pay-per-request API access"],"notFor":["Production workloads requiring documented request/response schemas","Users who need free or subscription-based API access","Applications requiring detailed API documentation or SLAs"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:59.259Z"},"updatedAt":"2026-04-27T21:34:10.246Z"}}