{"uid":"cap_-CMDYQ_PXRAD8lquk9PEx","slug":"fastpath-api-bitcoin-template-check-5e3dc8b7","name":"FastPath API – Bitcoin Template Check","description":"FastPath translates Ethereum-style JSON-RPC requests into Bitcoin data, fee intelligence, mempool insight, and Core v31 package signals. Paid by x402.","url":"https://api.nativebtc.org/v1/template/check","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"txid":{"type":"string","pattern":"^[0-9a-fA-F]{64}$","description":"Bitcoin transaction ID as 64 lowercase or uppercase hex characters."},"targetBlocks":{"type":"number","minimum":1,"description":"Desired confirmation target in blocks."}}},"responseSchema":{"type":"json","example":{"mode":"live_cached","source":"core_v31_optimizer_cache","success":true,"inBaselineTemplate":false,"inOptimizedTemplate":true}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.01","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":"$0.01/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.01","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_UNoROSnYN5mtAI9AVn3dJ","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.01","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Checks whether a Bitcoin transaction is included in Bitcoin Core v31's baseline or optimized fee-estimation templates for a given block-confirmation target","exampleAgentPrompt":"Check whether Bitcoin transaction a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2c3d4e5f6a1b2 is in Bitcoin Core v31's baseline or optimized fee template, targeting confirmation within 3 blocks.","exampleUseCases":[{"title":"Mempool template eligibility check","prompt":"Can you tell me if transaction 9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08 is currently in Bitcoin Core v31's optimized fee template for a 2-block confirmation target?"},{"title":"Fee optimization diagnostic for wallet dev","prompt":"I'm debugging my wallet's fee logic — check if txid 3a5f9c2e7b1d4e8f0c6a2d9b5e3f7a1c4d8b0e6f2a5c9d3b7e1f4a8c2d6b0e9f is part of Core v31's baseline or optimized template when targeting 6 blocks."},{"title":"Pre-broadcast transaction template validation","prompt":"Before I broadcast this transaction, I want to know if the txid 0000000000000000000000000000000000000000000000000000000000000001 will show up in Bitcoin Core's v31 optimized block template for a 1-block target — does it make it in?"}],"resultDescription":"Returns a JSON object indicating whether the queried transaction is present in Bitcoin Core v31's baseline template (inBaselineTemplate) and/or optimized template (inOptimizedTemplate), along with a success flag, the data mode (e.g. live_cached), and the source cache identifier.","failureModes":["Invalid txid format (not 64 hex characters) returns a validation error","Transaction not found in mempool or template cache returns success:false","targetBlocks below minimum (1) triggers a schema validation error","Network or upstream Bitcoin Core node unavailability causes a 5xx response","Payment not provided or x402 payment rejected results in 402 Payment Required"],"whenToPreferThis":"Use this endpoint when you need to determine whether a specific Bitcoin transaction has been selected by Bitcoin Core v31's fee-estimation template logic, particularly when comparing baseline vs. optimized selection. It is purpose-built for Core v31 package relay and template introspection, making it superior to generic mempool APIs that lack template-layer visibility.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T12:51:55.576Z","isFirstParty":false}