{"id":"f37ee9c8-c0df-499d-8ac4-98a439ff79c1","shortId":"ZDnxG7","kind":"x402","title":"Pay-per-call notification endpoint on Base via x402 — $0.02 per request in USDC.","tagline":"Pay-per-call notification endpoint on Base via x402 — $0.02 per request in USDC.","description":"This endpoint at `/api/v1/notifications/19` is part of the lowpaymentfee.com platform, which offers a collection of x402-protocol pay-per-request APIs spanning data & analytics, AI/ML, finance, infrastructure utilities, and notifications. Each call is settled on the Base network using USDC (USD Coin) at a cost of $0.02 per request. No API keys, rate limits, or subscriptions are required — callers simply attach an x402 payment header to each POST request.\n\nThe specific endpoint listed here is described only as \"Premium API Access\" with no further documentation on what the notification resource returns or what input it expects. The broader platform advertises categories including sentiment analysis, text summarization, classification, embeddings, price feeds, exchange rates, geocoding, validation, and more — all at the same $0.02/request price point. However, the `/api/v1/notifications/19` path is not listed on the homepage among the advertised APIs, so its exact functionality is unclear.\n\nThe x402 challenge is live and well-formed: it specifies the `exact` payment scheme on Base mainnet, paying to address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3` using the canonical Base USDC contract (`0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913`). The `maxAmountRequired` of 20000 base units equals $0.02 (USDC has 6 decimals). The endpoint accepts POST requests and returns `application/json`.","tags":[],"capabilities":["x402-payment","pay-per-request","usdc-settlement","base-network","notifications","json-response"],"categories":["infrastructure"],"synonyms":["x402 notification API","pay-per-call API","USDC micropayment endpoint","lowpaymentfee notifications","Base network API","402 payment required API"],"warnings":["The /api/v1/notifications/19 endpoint is not listed among the provider's advertised APIs on the homepage — its purpose is unknown.","No request or response schema is documented; callers must discover behavior empirically.","No OpenAPI spec, README, or detailed docs were found — /pricing, /api, and /README pages all returned only a wallet-connect prompt.","Functionality behind 'Premium API Access' is entirely opaque; treat as experimental."],"endpointUrl":"https://lowpaymentfee.com/api/v1/notifications/19","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/notifications/19","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The x402 challenge is live and pricing is clear ($0.02 USDC on Base), but there is no documentation on what this specific notifications endpoint does, what inputs it accepts, or what it returns. The endpoint path is not listed among the provider's advertised APIs. No OpenAPI spec, no examples, and crawled pages beyond the homepage returned only 'Connect wallet' with no useful 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'/request':154 '0.02':11,26,79,153,213 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':198 '0x833589fcd6edb6e08f4c7c32d4f71b54bda02913':205 '20000':209 '402 payment required API' '6':216 'Base network API' 'USDC micropayment endpoint' 'accept':220 'access':113 'address':197 'advertis':132,169 'ai/ml':57 'among':167 'analysi':136 'analyt':56 'api':53,83,112,170 'application/json':225 'attach':93 'base':8,23,69,193,202,210 'base-network' 'broader':130 'call':4,19,64 'caller':91 'canon':201 'categori':133 'challeng':179 'classif':139 'coin':74 'collect':44 'contract':204 'cost':77 'data':55 'decim':217 'describ':108 'document':117 'embed':140 'endpoint':6,21,32,104,219 'equal':212 'exact':173,189 'exchang':143 'expect':128 'feed':142 'financ':58 'form':185 'function':174 'geocod':145 'header':97 'homepag':166 'howev':157 'includ':134 'infrastructur':59 'input':126 'json-response' 'key':84 'limit':86 'list':105,163 'live':181 'lowpaymentfee notifications' 'lowpaymentfee.com':39 'mainnet':194 'maxamountrequir':207 'network':70 'notif':5,20,62,121 'notifications' 'offer':42 'part':36 'path':160 'pay':2,17,50,195 'pay-per-cal':1,16 'pay-per-call API' 'pay-per-request':49 'payment':96,190 'per':3,12,18,27,51,80 'platform':40,131 'point':156 'post':100,221 'premium':111 'price':141,155 'protocol':48 'rate':85,144 'request':13,28,52,81,101,222 'requir':90 'resourc':122 'return':123,224 'scheme':191 'sentiment':135 'settl':66 'simpli':92 'span':54 'specif':103 'specifi':187 'subscript':88 'summar':138 'text':137 'unclear':176 'unit':211 'usd':73 'usdc':15,30,72,203,214 'usdc-settlement' 'use':71,199 'util':60 'valid':146 'via':9,24 'well':184 'well-form':183 'x402':10,25,47,95,178 'x402 notification API' 'x402-payment' 'x402-protocol':46","prices":[{"id":"5a7fe30c-b76e-4368-9138-f91a9825a694","listingId":"f37ee9c8-c0df-499d-8ac4-98a439ff79c1","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/notifications/19","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:29.047Z"}],"sources":[{"listingId":"f37ee9c8-c0df-499d-8ac4-98a439ff79c1","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/notifications/19","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:29.047Z","lastSeenAt":"2026-04-22T02:32:10.582Z"}],"details":{"listingId":"f37ee9c8-c0df-499d-8ac4-98a439ff79c1","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/notifications/19 \\\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 platform advertises $0.02 per request with no API keys, no rate limits, and instant access on the Base network.","source_url":"https://lowpaymentfee.com"},{"claim":"The x402 challenge specifies maxAmountRequired of 20000 base units of USDC (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913) on Base, equaling $0.02.","source_url":"https://lowpaymentfee.com/api/v1/notifications/19"},{"claim":"The platform lists APIs across Data & Analytics, AI & ML, Finance & Web3, and Infrastructure categories.","source_url":"https://lowpaymentfee.com"}],"useCases":["Triggering or retrieving notification data via a single paid API call","Integrating pay-per-use notification services into agent workflows without API key management","Testing x402 payment protocol integrations on Base mainnet"],"bestFor":["Developers experimenting with x402 pay-per-request protocols","Agents needing keyless, on-demand API access settled in USDC on Base","Low-volume or sporadic notification retrieval without subscription overhead"],"notFor":["High-volume notification pipelines where $0.02/call adds up quickly","Users who need detailed documentation or guaranteed SLAs before integrating","Anyone without a Base-network USDC wallet"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:12:56.703Z"},"updatedAt":"2026-04-22T02:32:10.582Z"}}