{"id":"d4205d35-9279-42c4-9963-f4cf6dc94e27","shortId":"RF6CAN","kind":"x402","title":"Pay-per-call notification endpoint on Base via x402, settled in USDC at $0.02/request.","tagline":"Pay-per-call notification endpoint on Base via x402, settled in USDC at $0.02/request.","description":"This endpoint at lowpaymentfee.com provides a \"Premium API Access\" notification service accessible via the x402 payment protocol. It is one of many endpoints offered by the lowpaymentfee.com platform, which hosts a broad catalog of pay-per-call APIs spanning data & analytics, AI & machine learning, finance & Web3, and infrastructure utilities — all priced at $0.02 per request with no API keys, no rate limits, and no commitments.\n\nThe specific endpoint `/api/v1/notifications/20` accepts POST requests and is gated by an x402 challenge requiring payment of up to 20,000 base units of USDC (0x8335…2913) on the Base network, which equals $0.02 USD (USDC uses 6 decimals). Payment is made via the `exact` scheme to the address `0x1A2B13E97f5F837C8F9FA1F95a1484B7C70d85F3`, with a maximum timeout of 300 seconds. The response MIME type is `application/json`.\n\nDocumentation beyond the landing page is sparse — the /api, /pricing, and /README pages all resolve to a \"Connect wallet\" prompt with no further detail. There is no OpenAPI spec, no request/response schema documentation, and no examples of what the notification endpoint actually returns or what parameters it accepts. The endpoint is confirmed live (returns a proper 402 challenge), but the exact functionality behind \"notifications/20\" is unclear from available materials.","tags":[],"capabilities":["x402-payment","usdc-settlement","base-network","pay-per-call","notifications","no-api-key","json-response"],"categories":["notifications","infrastructure"],"synonyms":["x402 notification API","pay-per-request API","USDC micropayment endpoint","Base network API","lowpaymentfee","premium API access","crypto-paid notifications"],"warnings":["No documentation available for the /api/v1/notifications/20 endpoint — purpose and parameters are unknown","No OpenAPI or schema definition found","The /api, /pricing, and /README pages return only a 'Connect wallet' prompt with no useful content","The meaning of '20' in the endpoint path is unclear (could be an ID, a parameter, etc.)"],"endpointUrl":"https://lowpaymentfee.com/api/v1/notifications/20","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/20","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}]},"qualityScore":"0.300","qualityRationale":"The endpoint is confirmed live with a valid x402 402 challenge, and pricing is clear ($0.02 USDC on Base). However, there is no OpenAPI spec, no request/response schema, no documentation of what the notifications endpoint does or what parameters it accepts, and the /api, /pricing, and /README pages are all empty beyond a wallet-connect prompt. This is effectively a stub 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'/api/v1/notifications/20':102 '/pricing':171 '/readme':173 '/request':16,32 '0.02':15,31,86,132 '000':119 '0x1a2b13e97f5f837c8f9fa1f95a1484b7c70d85f3':148 '0x8335':124 '20':118 '2913':125 '300':154 '402':218 '6':136 'Base network API' 'USDC micropayment endpoint' 'accept':103,209 'access':41,44 'actual':203 'address':147 'ai':75 'analyt':74 'api':40,71,91 'application/json':161 'avail':229 'base':8,24,120,128 'base-network' 'behind':224 'beyond':163 'broad':64 'call':4,20,70 'catalog':65 'challeng':112,219 'commit':98 'confirm':213 'connect':179 'crypto-paid notifications' 'data':73 'decim':137 'detail':185 'document':162,194 'endpoint':6,22,34,55,101,202,211 'equal':131 'exact':143,222 'exampl':197 'financ':78 'function':223 'gate':108 'host':62 'infrastructur':81 'json-response' 'key':92 'land':165 'learn':77 'limit':95 'live':214 'lowpaymentfee' 'lowpaymentfee.com':36,59 'machin':76 'made':140 'mani':54 'materi':230 'maximum':151 'mime':158 'network':129 'no-api-key' 'notif':5,21,42,201 'notifications' 'notifications/20':225 'offer':56 'one':52 'openapi':189 'page':166,174 'paramet':207 'pay':2,18,68 'pay-per-cal':1,17,67 'pay-per-call' 'pay-per-request API' 'payment':48,114,138 'per':3,19,69,87 'platform':60 'post':104 'premium':39 'premium API access' 'price':84 'prompt':181 'proper':217 'protocol':49 'provid':37 'rate':94 'request':88,105 'request/response':192 'requir':113 'resolv':176 'respons':157 'return':204,215 'schema':193 'scheme':144 'second':155 'servic':43 'settl':11,27 'span':72 'spars':168 'spec':190 'specif':100 'timeout':152 'type':159 'unclear':227 'unit':121 'usd':133 'usdc':13,29,123,134 'usdc-settlement' 'use':135 'util':82 'via':9,25,45,141 'wallet':180 'web3':79 'x402':10,26,47,111 'x402 notification API' 'x402-payment'","prices":[{"id":"382d03e8-9af9-4781-bfc6-7bdbb94df455","listingId":"d4205d35-9279-42c4-9963-f4cf6dc94e27","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/20","description":"Premium API Access","outputSchema":{"input":{"type":"http","method":"GET","discoverable":true}},"maxAmountRequired":"20000","maxTimeoutSeconds":300}],"asset_contract":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","max_timeout_seconds":300},"createdAt":"2026-04-21T18:32:32.138Z"}],"sources":[{"listingId":"d4205d35-9279-42c4-9963-f4cf6dc94e27","source":"x402_bazaar","sourceId":"https://lowpaymentfee.com/api/v1/notifications/20","sourceUrl":"https://api.cdp.coinbase.com/platform/v2/x402/discovery/resources","isPrimary":true,"firstSeenAt":"2026-04-21T18:32:32.138Z","lastSeenAt":"2026-04-22T04:02:46.613Z"}],"details":{"listingId":"d4205d35-9279-42c4-9963-f4cf6dc94e27","quickStartSnippet":"curl -X POST https://lowpaymentfee.com/api/v1/notifications/20 \\\n  -H \"Content-Type: application/json\" \\\n  -H \"X-PAYMENT: <x402-payment-header>\" \\\n  -d '{}'","exampleRequest":null,"exampleResponse":null,"schema":{"input":{"type":"http","method":"GET","discoverable":true}},"openapiUrl":null,"agentsTxtUrl":null,"citations":[{"claim":"The endpoint returns a 402 challenge with maxAmountRequired of 20000 base units of USDC on Base network","source_url":"https://lowpaymentfee.com/api/v1/notifications/20"},{"claim":"All APIs on the platform are priced at $0.02 per request with no API keys, no rate limits, and instant access","source_url":"https://lowpaymentfee.com"},{"claim":"The platform offers APIs across Data & Analytics, AI & Machine Learning, Finance & Web3, and Infrastructure categories","source_url":"https://lowpaymentfee.com"},{"claim":"USDC contract address 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 on Base network","source_url":"https://lowpaymentfee.com/api/v1/notifications/20"}],"useCases":["Sending or retrieving notifications via a pay-per-call model without API key management","Integrating low-cost notification triggers into agent workflows settled on-chain","Testing x402 payment protocol integrations with a live, inexpensive endpoint"],"bestFor":["Developers experimenting with x402 payment-gated APIs","Agents needing simple pay-per-call notification endpoints on Base","Projects that want keyless API access with crypto micropayments"],"notFor":["Production notification systems requiring documented SLAs and detailed schemas","Users who need fiat-only payment options (this requires USDC on Base)","Applications needing high-throughput bulk notification delivery with guaranteed delivery semantics"],"kindDetails":{"x402_version":1,"resource_type":"http","bazaar_last_updated":"2026-02-17T23:12:51.428Z"},"updatedAt":"2026-04-22T04:02:46.613Z"}}