{"uid":"cap_m8S-sqoUFTcZHR2CQmnI6","slug":"pennyrail-json-key-lister-7a26e481","name":"PennyRail JSON Key Lister","description":"Machine-readable settlement service","url":"https://pennyrail.vercel.app/api/p/nano/json.keys--list-json-keys","method":"POST","headers":{},"bodySchema":{"type":"object","required":["input"],"properties":{"input":{"type":"object"}}},"responseSchema":{"type":"object","additionalProperties":true},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_1knDssXubZFVAm-rP7DqB","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Extracts and returns a flat list of all top-level keys present in a given JSON object","exampleAgentPrompt":"Can you list all the top-level keys in this JSON object for me: {\"name\": \"Alice\", \"age\": 30, \"roles\": [\"admin\"], \"active\": true}?","exampleUseCases":[{"title":"Inspect unknown API response structure","prompt":"I got back this JSON from an API and I'm not sure what fields it contains — can you list all the keys so I know what I'm working with: {\"id\": \"abc123\", \"ts\": 1700000000, \"payload\": {}, \"status\": \"ok\"}?"},{"title":"Validate expected fields in JSON payload","prompt":"Can you pull out all the top-level keys from this JSON so I can check whether the required fields like 'userId' and 'amount' are present: {\"userId\": \"u99\", \"amount\": 42, \"currency\": \"USD\"}?"},{"title":"Document JSON schema from live data","prompt":"I'm writing documentation and need to know every key this JSON object exposes — can you enumerate them for me: {\"product\": \"Widget\", \"sku\": \"W-001\", \"price\": 9.99, \"inStock\": true, \"tags\": []}?"}],"resultDescription":"A JSON object containing a list of all top-level key names extracted from the provided input object. The response is machine-readable and enumerates each property name present at the root level of the submitted JSON.","failureModes":["Missing or malformed 'input' field returns an error — input must be a JSON object, not a scalar or array","Empty object input returns an empty key list rather than an error","Non-object values nested inside the input are not recursively enumerated — only top-level keys are returned","Payment failure (402) if USDC balance or x402 authorization is insufficient","Vercel cold-start latency may cause occasional slow responses on first call"],"whenToPreferThis":"Choose this endpoint when you need a quick, paid, machine-readable enumeration of top-level JSON keys without setting up any local parsing logic. It is useful in agent pipelines where the JSON structure of a dynamic or unknown payload needs to be discovered programmatically before downstream processing. Prefer it over custom code when operating in a tool-calling context where invoking a microservice is more convenient than running code.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T07:16:54.215Z","isFirstParty":false}