{"id":"4554601d-77a9-423f-8fb8-7a277c4798ba","shortId":"MKgWDr","kind":"x402","title":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.","tagline":"x402-gated portfolio endpoint on Base, pay $0.02 per request in USDC — no API keys required.","description":"This endpoint at `/api/v1/portfolios/18` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data analytics, AI/ML inference, finance/Web3, and infrastructure utilities. The specific `/portfolios/18` resource is listed under \"Premium API Access\" but its exact data payload is not documented beyond the generic description. All endpoints on the platform share the same pricing model: $0.02 per request, settled in USDC on the Base network.\n\nThe endpoint is live and returns a valid x402 challenge (HTTP 402) with `maxAmountRequired` of 20000 base units of USDC (0x8335…2913 on Base, 6 decimals), which equals $0.02. Payment is made via the x402 `exact` scheme by including an `X-PAYMENT` header. There are no API keys, no rate limits, and no subscription commitments — callers simply attach a valid x402 payment header to each POST request.\n\nDocumentation is extremely sparse. The crawled docs, API, pricing, and README pages all returned only a \"Connect wallet\" prompt with no substantive content. There is no OpenAPI spec, no request/response schema, and no explanation of what the `/portfolios/18` resource actually returns. The platform appears to be a demonstration or early-stage deployment of x402-gated microservices. Without knowing the response schema or the nature of the \"portfolio\" data, agents should treat this as an exploratory integration.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","portfolio-data","no-api-key","no-rate-limit"],"categories":["finance","data"],"synonyms":["portfolio API","x402 API","pay-per-call API","USDC micropayment API","Base network API","lowpaymentfee","premium API access"],"warnings":["No documentation available — all doc/API/pricing/README pages return only 'Connect wallet' with no content.","No OpenAPI or request/response schema provided; the actual data returned by /portfolios/18 is unknown.","Platform appears to be early-stage or a demo; reliability and data quality are unverified.","The specific meaning of 'portfolios/18' is undocumented — it could be placeholder or test data."],"endpointUrl":"https://lowpaymentfee.com/api/v1/portfolios/18","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/18","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, but there is zero documentation on what the /portfolios/18 resource returns, no OpenAPI spec, no request body schema, and no example responses. Docs pages are empty beyond a wallet-connect prompt. This is effectively a stub 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'/portfolios/18':69,214 '0.02':9,26,99,137 '0x8335':129 '20000':124 '2913':130 '402':120 '6':133 'Base network API' 'USDC micropayment API' 'access':76 'actual':216 'agent':247 'ai/ml':61 'analyt':60 'api':15,32,57,75,156,184 'appear':220 'attach':167 'base':7,24,107,125,132 'beyond':85 'caller':165 'challeng':118 'collect':48 'commit':164 'connect':193 'content':199 'crawl':182 'data':59,80,246 'decim':134 'demonstr':224 'deploy':229 'descript':88 'doc':183 'document':84,177 'earli':227 'early-stag':226 'endpoint':5,22,36,90,110 'equal':136 'exact':79,144 'explan':210 'exploratori':253 'extrem':179 'finance/web3':63 'gate':3,20,233 'generic':87 'header':152,172 'http':119 'includ':147 'infer':62 'infrastructur':65 'integr':254 'key':16,33,157 'know':236 'limit':160 'list':72 'live':112 'lowpaymentfee' 'lowpaymentfee.com':43 'made':140 'maxamountrequir':122 'microservic':234 'model':98 'natur':242 'network':108 'no-api-key' 'no-rate-limit' 'offer':46 'openapi':203 'page':188 'part':40 'pay':8,25,54 'pay-per-call API' 'pay-per-request':53 'payload':81 'payment':138,151,171 'per':10,27,55,100 'platform':44,93,219 'portfolio':4,21,245 'portfolio API' 'portfolio-data' 'post':175 'premium':74 'premium API access' 'price':97,185 'prompt':195 'protocol':52 'rate':159 'readm':187 'request':11,28,56,101,176 'request/response':206 'requir':17,34 'resourc':70,215 'respons':238 'return':114,190,217 'schema':207,239 'scheme':145 'settl':102 'share':94 'simpli':166 'span':58 'spars':180 'spec':204 'specif':68 'stage':228 'subscript':163 'substant':198 'treat':249 'unit':126 'usdc':13,30,104,128 'usdc-base' 'util':66 'valid':116,169 'via':141 'wallet':194 'without':235 'x':150 'x-payment':149 'x402':2,19,51,117,143,170,232 'x402 API' 'x402-gated':1,18,231 'x402-payment' 'x402-protocol':50","prices":[{"id":"95ee666f-7b05-4da2-a3db-413282b7ad13","listingId":"4554601d-77a9-423f-8fb8-7a277c4798ba","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/18","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:52:14.669Z"}],"sources":[{"listingId":"4554601d-77a9-423f-8fb8-7a277c4798ba","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/portfolios/18","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:52:14.669Z","lastSeenAt":"2026-04-28T07:34:37.706Z"}],"details":{"listingId":"4554601d-77a9-423f-8fb8-7a277c4798ba","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/portfolios/18 \\\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":"The endpoint returns a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/portfolios/18"},{"claim":"All endpoints on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset contract on Base is 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","source_url":"https://lowpaymentfee.com/api/v1/portfolios/18"},{"claim":"Docs, API, pricing, and README pages returned only 'Connect wallet' with no substantive content","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Fetching portfolio data on-demand with per-request USDC micropayments","Integrating x402-gated endpoints into autonomous agent workflows","Testing x402 protocol payment flows on Base network"],"bestFor":["Developers experimenting with x402 pay-per-request protocols","Agents that need keyless, permissionless API access settled in USDC","Low-volume or sporadic data consumers who prefer pay-as-you-go"],"notFor":["Production workloads requiring well-documented request/response schemas","High-volume consumers who need bulk pricing or subscription discounts","Users without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:01.779Z"},"updatedAt":"2026-04-28T07:34:37.706Z"}}