{"id":"36c41628-1038-4e9a-9b0b-d7db455b751f","shortId":"fRkx6y","kind":"x402","title":"Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.","tagline":"Pay-per-call premium API access on Base via x402 — $0.02/request in USDC.","description":"This endpoint at lowpaymentfee.com provides \"Premium API Access\" via the x402 payment protocol. The probed endpoint (/api/v1/payments/237) returns a valid 402 challenge requesting payment in USDC on the Base network. The site advertises a broad catalog of API endpoints spanning data & analytics, AI & machine learning (sentiment analysis, text summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation) — all priced at $0.02 per request.\n\nThe x402 challenge for this specific endpoint specifies a maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base, 6 decimals), which equals $0.02 USD. Payment is made via the \"exact\" scheme to address 0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3 with a 300-second timeout. No API keys or rate limits are advertised; access is instant upon payment.\n\nHowever, the specific functionality behind the /api/v1/payments/237 path is unclear — the description simply says \"Premium API Access\" without detailing what data or service is returned. The docs, pricing, and API pages all render only a \"Connect wallet\" prompt with no further documentation. There is no OpenAPI spec, no request/response schema beyond the x402 outputSchema stub, and no examples of what a successful response looks like. The site appears to be a demonstration or early-stage platform for x402-gated microservices.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","no-api-key","microservice-gateway"],"categories":["api-gateway","crypto"],"synonyms":["x402 API","micropayment API","USDC pay-per-call","Base network API","lowpaymentfee","crypto API gateway","402 payment endpoint"],"warnings":["No documentation available — docs, pricing, and API pages all show only 'Connect wallet'","No OpenAPI or request/response schema provided","The specific functionality of /api/v1/payments/237 is not described beyond 'Premium API Access'","Cannot verify what data or service is actually returned upon successful payment","Site may be a demo or early-stage platform"],"endpointUrl":"https://lowpaymentfee.com/api/v1/payments/237","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/payments/237","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 402 challenge, confirming it accepts USDC on Base at $0.02/request. However, there is no documentation, no OpenAPI spec, no request/response examples, and the specific functionality of /api/v1/payments/237 is undescribed. The docs and other pages render only wallet-connect prompts. This is effectively a stub 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'/request':13,28 '0.02':12,27,102,128 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':139 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':121 '20000':116 '300':142 '402':51 '402 payment endpoint' '6':124 'Base network API' 'USDC pay-per-call' 'access':7,22,38,153,174 'address':138 'advertis':63,152 'ai':73 'analysi':77 'analyt':72 'api':6,21,37,68,146,173,187 'appear':225 'base':9,24,59,117,123 'behind':162 'beyond':208 'broad':65 'call':4,19 'catalog':66 'challeng':52,107 'classif':80 'connect':193 'convers':97 'crypto API gateway' 'data':71,178 'decim':125 'demonstr':229 'descript':169 'detail':176 'doc':184 'document':199 'earli':232 'early-stag':231 'embed':81 'endpoint':32,46,69,111 'equal':127 'estim':91 'exact':135 'exampl':215 'exchang':86 'feed':85 'financ':82 'function':161 'gas':90 'gate':238 'generat':98 'geocod':95 'howev':158 'infrastructur':93 'instant':155 'key':147 'learn':75 'like':222 'limit':150 'look':221 'lowpaymentfee' 'lowpaymentfee.com':34 'machin':74 'made':132 'maxamountrequir':114 'micropayment API' 'microservic':239 'microservice-gateway' 'network':60 'no-api-key' 'openapi':203 'outputschema':211 'page':188 'path':165 'pay':2,17 'pay-per-cal':1,16 'pay-per-request' 'payment':42,54,130,157 'per':3,18,103 'platform':234 'premium':5,20,36,172 'price':84,100,185 'probe':45 'prompt':195 'protocol':43 'provid':35 'quot':89 'rate':87,149 'render':190 'request':53,104 'request/response':206 'respons':220 'return':48,182 'say':171 'schema':207 'scheme':136 'second':143 'sentiment':76 'servic':180 'simpli':170 'site':62,224 'span':70 'spec':204 'specif':110,160 'specifi':112 'stage':233 'stub':212 'success':219 'summar':79 'text':78 'timeout':144 'token':88 'unclear':167 'unit':118 'upon':156 'usd':129 'usdc':15,30,56,120 'usdc-base' 'util':94 'valid':50,96 'via':10,25,39,133 'wallet':194 'web3':83 'without':175 'x402':11,26,41,106,210,237 'x402 API' 'x402-gated':236 'x402-payment'","prices":[{"id":"0717bf55-3e23-4ee1-bb28-8d681e8b2000","listingId":"36c41628-1038-4e9a-9b0b-d7db455b751f","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/payments/237","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:50:00.838Z"}],"sources":[{"listingId":"36c41628-1038-4e9a-9b0b-d7db455b751f","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/payments/237","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:50:00.838Z","lastSeenAt":"2026-04-23T14:01:24.002Z"}],"details":{"listingId":"36c41628-1038-4e9a-9b0b-d7db455b751f","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/payments/237 \\\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 402 challenge requesting 20000 base units of USDC on Base (=$0.02)","source_url":"https://lowpaymentfee.com/api/v1/payments/237"},{"claim":"The site advertises $0.02/request 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/payments/237"},{"claim":"Available API categories include Data & Analytics, AI & ML, Finance & Web3, and Infrastructure","source_url":"https://lowpaymentfee.com"}],"useCases":["Agents that need on-demand API access without pre-registration or API keys","Programmatic micropayment-gated service consumption on Base L2","Testing x402 payment protocol integrations with a low-cost endpoint"],"bestFor":["Developers exploring x402 payment protocol integration","AI agents needing keyless, pay-per-call API access","Low-cost per-request microservice consumption on Base"],"notFor":["Production workloads requiring documented request/response schemas","Users who need detailed API documentation or SLA guarantees","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:08.305Z"},"updatedAt":"2026-04-23T14:01:24.002Z"}}