{"id":"dd8d95ad-2a3d-4720-9404-698018dd2cd0","shortId":"ju9Tbb","kind":"x402","title":"Pay-per-request API collection on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.","tagline":"Pay-per-request API collection on Base via x402 — data, AI, finance, and utility endpoints at $0.02/call.","description":"lowpaymentfee.com hosts a collection of pay-per-request API endpoints accessible via the x402 payment protocol on the Base network. The specific endpoint at `/api/v1/collections/6` is labeled \"Premium API Access\" and accepts POST requests, settling payments in USDC (USD Coin) on Base. The x402 challenge advertises a maximum amount of 20,000 base units of USDC (6 decimals), which equals $0.02 per request.\n\nThe provider's landing page lists four categories of APIs: Data & Analytics (metrics, reports, data export, insights), 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 endpoints are listed at $0.02 per request with no API keys, no rate limits, and no minimum commitments required.\n\nDocumentation beyond the landing page is extremely sparse — the docs, API, pricing, and README pages all render only a \"Connect wallet\" prompt with no further content. There is no OpenAPI schema, no request/response examples, and no detailed documentation for any endpoint. The `/api/v1/collections/6` endpoint itself is live (returns a valid 402 challenge), but what data it actually returns upon successful payment is unknown from the available material.","tags":[],"capabilities":["x402-payment","pay-per-request","usdc-settlement","base-network","data-analytics","ai-inference","sentiment-analysis","text-summarization","classification","embeddings","finance-data","geocoding","utility-apis"],"categories":["data","llm","finance","utility"],"synonyms":["low payment fee API","x402 API","micropayment API","pay-per-call API","Base USDC API","crypto-paid API","lowpaymentfee"],"warnings":["No API documentation available — docs, pricing, and README pages all show only 'Connect wallet' with no content","No OpenAPI or schema definition for any endpoint","The specific purpose of /api/v1/collections/6 ('Premium API Access') is not described anywhere — unclear what it returns","No request or response examples available","Cannot verify what any of the listed endpoints actually do without paying"],"endpointUrl":"https://lowpaymentfee.com/api/v1/collections/6","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/collections/6","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, confirming it accepts USDC payments on Base at $0.02/request. However, there is no OpenAPI schema, no request/response examples, and all documentation pages are empty beyond a wallet-connect prompt. The actual functionality behind '/api/v1/collections/6' is undocumented — it's unclear what data or service it provides upon 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'/call':19,38 '0.02':18,37,100,151 '000':91 '20':90 '402':216 '6':96 'Base USDC API' 'accept':71 'access':50,69 'actual':222 'advertis':85 'ai':12,31,120 'ai-inference' 'amount':88 'analysi':124 'analyt':114 'api':5,24,48,68,112,156,176 'avail':231 'base':8,27,58,81,92 'base-network' 'beyond':167 'categori':110 'challeng':84,217 'classif':127 'classification' 'coin':79 'collect':6,25,42 'commit':164 'connect':185 'content':191 'convers':144 'crypto-paid API' 'data':11,30,113,117,220 'data-analytics' 'decim':97 'detail':202 'doc':175 'document':166,203 'embed':128 'embeddings' 'endpoint':16,35,49,62,147,206,209 'equal':99 'estim':138 'exampl':199 'exchang':133 'export':118 'extrem':172 'feed':132 'financ':13,32,129 'finance-data' 'four':109 'gas':137 'generat':145 'geocod':142 'geocoding' 'host':40 'infrastructur':140 'insight':119 'key':157 'label':66 'land':106,169 'learn':122 'limit':160 'list':108,149 'live':212 'low payment fee API' 'lowpaymentfee' 'lowpaymentfee.com':39 'machin':121 'materi':232 'maximum':87 'metric':115 'micropayment API' 'minimum':163 'network':59 'openapi':195 'page':107,170,180 'pay':2,21,45 'pay-per-call API' 'pay-per-request':1,20,44 'payment':54,75,226 'per':3,22,46,101,152 'post':72 'premium':67 'price':131,177 'prompt':187 'protocol':55 'provid':104 'quot':136 'rate':134,159 'readm':179 'render':182 'report':116 'request':4,23,47,73,102,153 'request/response':198 'requir':165 'return':213,223 'schema':196 'sentiment':123 'sentiment-analysis' 'settl':74 'spars':173 'specif':61 'success':225 'summar':126 'text':125 'text-summarization' 'token':135 'unit':93 'unknown':228 'upon':224 'usd':78 'usdc':77,95 'usdc-settlement' 'util':15,34,141 'utility-apis' 'valid':143,215 'via':9,28,51 'wallet':186 'web3':130 'x402':10,29,53,83 'x402 API' 'x402-payment'","prices":[{"id":"e04fd557-d133-4a89-b561-c7ab3d562cfb","listingId":"dd8d95ad-2a3d-4720-9404-698018dd2cd0","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/collections/6","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-19T05:29:50.545Z"}],"sources":[{"listingId":"dd8d95ad-2a3d-4720-9404-698018dd2cd0","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/collections/6","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-19T05:29:50.545Z","lastSeenAt":"2026-04-22T18:04:44.684Z"}],"details":{"listingId":"dd8d95ad-2a3d-4720-9404-698018dd2cd0","quickStartSnippet":"# The endpoint requires an x402 payment header (USDC on Base, $0.02/call)\ncurl -X POST https://lowpaymentfee.com/api/v1/collections/6 \\\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 a valid x402 challenge with maxAmountRequired of 20000 base units of USDC on Base","source_url":"https://lowpaymentfee.com/api/v1/collections/6"},{"claim":"All listed endpoints are priced at $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"The provider lists four categories: Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure","source_url":"https://lowpaymentfee.com"},{"claim":"USDC asset address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/collections/6"}],"useCases":["Accessing data analytics and reports without API key management","Running AI inference tasks (sentiment, summarization, classification, embeddings) on a per-call payment basis","Fetching real-time financial data like exchange rates, token quotes, and gas estimates","Using utility services like geocoding, validation, and conversion with instant crypto payment"],"bestFor":["Agents or developers who want keyless, pay-per-use API access via crypto","Quick prototyping without subscription commitments","Scenarios where Base-network USDC micropayments are preferred over traditional billing"],"notFor":["Users who need detailed API documentation or guaranteed SLAs before integrating","High-volume production workloads where $0.02/request adds up and bulk pricing is needed","Users without access to USDC on the Base network"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:13:24.553Z"},"updatedAt":"2026-04-22T18:04:44.684Z"}}