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FastPath API - Bitcoin Transaction Replacement Lookup
x402
FastPath API - Bitcoin Transaction Replacement Lookup is a paid API for AI agents from api.nativebtc.org, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-12).
Returns RBF (Replace-By-Fee) replacement history and status for a specific Bitcoin transaction by txid
Price / call$0.001
Success—
StatusUnknown
How this service works
FastPath translates Ethereum-style JSON-RPC requests into Bitcoin data, fee intelligence, mempool insight, and Core v31 package signals. Paid by x402.
Output
Returns a JSON object containing the original txid, a success boolean, a replaced boolean indicating whether the transaction was superseded via RBF, and an array of replacement transactions (empty if not replaced).
Example use cases
Verify if payment was RBF-replaced
“I sent a Bitcoin payment yesterday with txid 81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325 and it's still unconfirmed — can you check if it was replaced by a fee bump transaction?”
Debug vanished mempool transaction
“A Bitcoin transaction I submitted dropped out of the mempool with txid 3a1b2c4d5e6f7890abcdef1234567890abcdef1234567890abcdef1234567890 — can you look up whether it was replaced by an RBF transaction and show me any replacements?”
Monitor RBF bump chain for wallet reconciliation
“For my wallet reconciliation I need to know if txid 9f8e7d6c5b4a3210fedcba9876543210fedcba9876543210fedcba9876543210 had any RBF replacements — can you pull the full replacement list so I can track the correct transaction?”
Technical details
Endpoint
GEThttps://api.nativebtc.org/v1/mempool/tx/%7Btxid%7D/replacementsWhen to prefer
Use this endpoint when you need to determine whether a specific Bitcoin transaction was replaced via Replace-By-Fee (RBF) and want the full replacement chain. Prefer it over generic blockchain explorers when you need programmatic access to RBF replacement data, especially when building agents or automation that track payment finality on Bitcoin. It is purpose-built for mempool intelligence and uses Ethereum-style JSON-RPC conventions familiar to EVM developers.
Side effects
- Invalid or malformed txid returns an error or empty result
- Transaction not found in mempool history returns success:false or empty replacements
- Network timeout or upstream Bitcoin node unavailability
- Payment required (402) if x402 payment header is missing or invalid
- Transaction too old may not be indexed in mempool history
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| properties | string |
Output
Schema · Response
{
"type": "json",
"example": {
"txid": "81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325",
"success": true,
"replaced": false,
"replacements": []
}
}Tags
x402
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