{"id":"3aff71cc-0271-4349-b850-27e20df04e18","shortId":"t6GHS5","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 site hosts a broad catalog of pay-per-request APIs spanning data & analytics, AI/ML inference (sentiment analysis, summarization, classification, embeddings), finance & Web3 (price feeds, exchange rates, token quotes, gas estimates), and infrastructure utilities (geocoding, validation, conversion, generation). All endpoints are priced at $0.02 per request, payable in USDC on the Base network with no API keys, no rate limits, and no commitments required.\n\nThe specific endpoint `/api/v1/charges/137` is labeled \"Premium API Access\" and accepts POST requests. The x402 challenge advertises a max amount of 20,000 base units of USDC (0x8335…2913 on Base), which equals $0.02 given USDC's 6 decimals. Payment is made via the x402 exact scheme with a 300-second timeout. No OpenAPI schema, detailed documentation, or example request/response bodies were found in the crawl — the docs, pricing, API, and README pages all rendered only a \"Connect wallet\" prompt with no substantive content.\n\nBecause the endpoint labeled \"Premium API Access\" at `/api/v1/charges/137` does not clearly map to any of the named API categories on the landing page, it is unclear exactly what data or functionality this specific charge ID returns. The site's documentation is effectively empty beyond the landing page catalog. Agents should treat this as a generic paid endpoint until more documentation surfaces.","tags":[],"capabilities":["x402-payment","usdc-base","pay-per-request","no-api-key","post-endpoint","json-response"],"categories":["api","infrastructure"],"synonyms":["lowpaymentfee","low payment fee API","x402 API","USDC pay-per-call","Base network API","micropayment API","premium API access"],"warnings":["No OpenAPI or schema documentation available for this endpoint","Docs, pricing, API, and README pages all render only 'Connect wallet' with no content","The charge ID 137 does not map to any named API on the landing page — unclear what it returns","No example request or response bodies available"],"endpointUrl":"https://lowpaymentfee.com/api/v1/charges/137","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/charges/137","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.350","qualityRationale":"The endpoint is live and returns a valid x402 402 challenge, and the landing page provides a catalog overview with pricing. However, there is no OpenAPI schema, no documentation beyond a wallet-connect prompt, no example requests or responses, and the specific charge ID (137) is not explained anywhere. This is effectively a stub 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'/request':13,28 '0.02':12,27,88,142 '000':131 '0x8335':136 '20':130 '2913':137 '300':158 '6':146 'Base network API' 'USDC pay-per-call' 'accept':119 'access':7,22,38,117,199 'advertis':125 'agent':242 'ai/ml':59 'amount':128 'analysi':62 'analyt':58 'api':6,21,37,55,100,116,178,198,211 'base':9,24,96,132,139 'beyond':237 'bodi':169 'broad':48 'call':4,19 'catalog':49,241 'categori':212 'challeng':124 'charg':227 'classif':64 'clear':204 'commit':107 'connect':186 'content':192 'convers':81 'crawl':174 'data':57,222 'decim':147 'detail':164 'doc':176 'document':165,233,253 'effect':235 'embed':65 'empti':236 'endpoint':32,84,111,195,250 'equal':141 'estim':75 'exact':154,220 'exampl':167 'exchang':70 'feed':69 'financ':66 'found':171 'function':224 'gas':74 'generat':82 'generic':248 'geocod':79 'given':143 'host':46 'id':228 'infer':60 'infrastructur':77 'json-response' 'key':101 'label':114,196 'land':215,239 'limit':104 'low payment fee API' 'lowpaymentfee' 'lowpaymentfee.com':34 'made':150 'map':205 'max':127 'micropayment API' 'name':210 'network':97 'no-api-key' 'openapi':162 'page':181,216,240 'paid':249 'pay':2,17,52 'pay-per-cal':1,16 'pay-per-request':51 'payabl':91 'payment':42,148 'per':3,18,53,89 'post':120 'post-endpoint' 'premium':5,20,36,115,197 'premium API access' 'price':68,86,177 'prompt':188 'protocol':43 'provid':35 'quot':73 'rate':71,103 'readm':180 'render':183 'request':54,90,121 'request/response':168 'requir':108 'return':229 'schema':163 'scheme':155 'second':159 'sentiment':61 'site':45,231 'span':56 'specif':110,226 'substant':191 'summar':63 'surfac':254 'timeout':160 'token':72 'treat':244 'unclear':219 'unit':133 'usdc':15,30,93,135,144 'usdc-base' 'util':78 'valid':80 'via':10,25,39,151 'wallet':187 'web3':67 'x402':11,26,41,123,153 'x402 API' 'x402-payment'","prices":[{"id":"4ffc3e62-0900-4210-82fc-92b1fd5dcb2e","listingId":"3aff71cc-0271-4349-b850-27e20df04e18","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/charges/137","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-18T18:44:13.375Z"}],"sources":[{"listingId":"3aff71cc-0271-4349-b850-27e20df04e18","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/charges/137","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-18T18:44:13.375Z","lastSeenAt":"2026-04-22T13:30:56.945Z"}],"details":{"listingId":"3aff71cc-0271-4349-b850-27e20df04e18","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/charges/137 \\\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 x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/charges/137"},{"claim":"All listed APIs are priced at $0.02 per request with no API keys, no rate limits, and instant access on Base network","source_url":"https://lowpaymentfee.com"},{"claim":"The site offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"}],"useCases":["Paying per-call for API access without needing API keys or subscriptions","Integrating x402-compatible agents with low-cost utility endpoints on Base","Accessing data, AI, finance, or infrastructure APIs with USDC micropayments"],"bestFor":["Agents that support x402 payment protocol on Base","Developers wanting zero-commitment, pay-as-you-go API access","Use cases requiring keyless, rate-limit-free API calls"],"notFor":["Users who need detailed API documentation or OpenAPI specs before integrating","High-volume batch workloads where per-request pricing may add up","Anyone without a Base-compatible USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:14:25.053Z"},"updatedAt":"2026-04-22T13:30:56.945Z"}}