{"id":"8828978e-a117-42cf-abc3-fc9b5e20f3c0","shortId":"n8cZHY","kind":"x402","title":"x402-gated card-transactions endpoint on Base, pay $0.02 per request in USDC.","tagline":"x402-gated card-transactions endpoint on Base, pay $0.02 per request in USDC.","description":"This endpoint at lowpaymentfee.com exposes a card-transactions resource at `/api/v1/cards/71/transactions` behind an x402 payment challenge. It is part of a broader platform that offers dozens of pay-per-call APIs spanning data analytics, AI/ML inference, finance/Web3 data, and infrastructure utilities — all gated via the x402 protocol on the Base network.\n\nThe specific endpoint probed here accepts POST requests and returns JSON. The x402 challenge advertises a maximum cost of 20,000 base units of USDC (contract `0x8335…2913` on Base), which equals $0.02 per request (USDC uses 6 decimals). The platform's landing page confirms a flat $0.02/request pricing model across all endpoints, with no API keys, no rate limits, and no minimum commitments required.\n\nDocumentation is extremely sparse — the /docs, /pricing, /api, and /README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI spec, no request/response schema, and no usage examples available. The endpoint's purpose (\"card transactions\") and expected input/output formats must be inferred from the URL path alone. The platform appears to be a demonstration or early-stage x402 marketplace rather than a mature, well-documented API provider.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","card-transactions","post-json"],"categories":["finance","infrastructure"],"synonyms":["card transactions API","x402 payment API","lowpaymentfee","USDC micropayment API","Base network API","pay-per-call API","402 payment required"],"warnings":["No OpenAPI or schema documentation available — request/response formats are unknown","All documentation pages (/docs, /pricing, /api, /README) render only 'Connect wallet' with no content","The specific purpose of '/api/v1/cards/71/transactions' is unclear — 'Premium API Access' is a generic label","Platform appears to be early-stage or a demo; reliability and data quality are unverifiable"],"endpointUrl":"https://lowpaymentfee.com/api/v1/cards/71/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/cards/71/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 zero documentation on request/response schemas, no OpenAPI spec, no examples, and the docs pages are empty. The endpoint's actual functionality (what 'card transactions' means, what inputs it expects) is entirely 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'/api/v1/cards/71/transactions':42 '/docs':155 '/pricing':156 '/readme':159 '/request':132 '0.02':11,26,116,131 '000':104 '0x8335':110 '20':103 '2913':111 '402 payment required' '6':121 'Base network API' 'USDC micropayment API' 'accept':89 'across':135 'advertis':98 'ai/ml':67 'alon':202 'analyt':66 'api':63,140,223 'appear':205 'avail':184 'base':9,24,82,105,113 'behind':43 'broader':53 'call':62 'card':5,20,38,189 'card transactions API' 'card-transact':4,19,37 'card-transactions' 'challeng':47,97 'commit':148 'confirm':128 'connect':165 'content':171 'contract':109 'cost':101 'data':65,70 'decim':122 'demonstr':209 'document':150,222 'dozen':57 'earli':212 'early-stag':211 'endpoint':7,22,32,86,137,186 'equal':115 'exampl':183 'expect':192 'expos':35 'extrem':152 'finance/web3':69 'flat':130 'format':194 'gate':3,18,75 'infer':68,197 'infrastructur':72 'input/output':193 'json':94 'key':141 'land':126 'limit':144 'lowpaymentfee' 'lowpaymentfee.com':34 'marketplac':215 'matur':219 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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/cards/71/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":"2026-04-18T18:43:44.880Z"}],"sources":[{"listingId":"8828978e-a117-42cf-abc3-fc9b5e20f3c0","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/cards/71/transactions","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:43:44.880Z","lastSeenAt":"2026-04-27T04:33:54.113Z"}],"details":{"listingId":"8828978e-a117-42cf-abc3-fc9b5e20f3c0","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/cards/71/transactions \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-token>\" \\\n  -d '{}'","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The x402 challenge advertises maxAmountRequired of 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/cards/71/transactions"},{"claim":"The platform advertises $0.02/request flat pricing 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/cards/71/transactions"},{"claim":"Documentation pages (/docs, /pricing, /api, /README) contain only 'Connect wallet' text","source_url":"https://lowpaymentfee.com/docs"}],"useCases":["Querying card transaction data via a pay-per-request model without API keys","Integrating x402-compatible agents that can autonomously pay for API access","Testing x402 protocol payment flows on Base mainnet"],"bestFor":["Developers experimenting with x402 payment protocol","Agents that need keyless, pay-per-call API access on Base","Prototyping micropayment-gated API workflows"],"notFor":["Production workloads requiring well-documented, stable APIs with SLAs","Use cases needing detailed request/response schemas and error handling documentation","High-volume consumers who need bulk pricing or rate-limit guarantees"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:26.383Z"},"updatedAt":"2026-04-27T04:33:54.113Z"}}