# NativeBTC Optimized Block Template TxID List

> NativeBTC Optimized Block Template TxID List is a paid API for AI agents from api.nativebtc.org, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-15).

Returns an optimized, fee-maximizing ordered list of up to 4,000 transaction IDs for a Bitcoin block template, with fee uplift metrics and Ed25519 receipt metadata for Stratum V2 Job Declaration workflows.

## Facts

- Endpoint: POST https://api.nativebtc.org/v1/template/optimized-txids
- Price: $0.05/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/nativebtc-optimized-block-template-txid-list-76f12f9f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_fvT_3pRkGtgqGhgXEoMTy

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability nativebtc-optimized-block-template-txid-list-76f12f9f -d '<json body>'
```

Example prompt: Pull the latest optimized block template txid list from the NativeBTC Core v31 cache — I need up to 4,000 txids ordered by fee priority with the fee uplift comparison and Ed25519 receipt for my Stratum V2 job declaration workflow.

## When to prefer this

Choose this endpoint when building a Bitcoin mining operation or pool that uses Stratum V2 Job Declaration protocol and needs a ready-to-use, fee-optimized ordered transaction set with cryptographic proof of template validity. It is specifically valuable when you want to compare baseline Core mempool ordering against an actively optimized selection to measure and capture fee uplift, rather than constructing a block template yourself from raw mempool data.

## Known failure modes

- Mempool data temporarily unavailable — optimizer cache miss or node sync lag
- Payment not received or x402 payment header invalid — returns 402 Payment Required
- Block weight constraint results in fewer than expected txids returned
- Ed25519 signing service unavailable — receipt metadata missing or malformed
- Rate limit exceeded for the $0.05 USDC per-call pricing tier
- Malformed POST body — missing required fields returns 400 Bad Request

## How this service works

Full optimized block template txid list from the live Core v31 optimizer cache. Requests up to 4,000 txids, constrained by Bitcoin block weight. Returns ordered txids, template metadata, baseline-vs-optimized fee totals, mempool size, fee uplift, baseline comparison, coinbase value, and Ed25519 receipt metadata for Stratum V2 Job Declaration workflows.

## Output

An ordered list of up to 4,000 Bitcoin transaction IDs selected and ranked by the Core v31 optimizer to maximize block fees within Bitcoin block weight limits, along with template metadata, baseline vs. optimized fee totals, current mempool size, fee uplift figure, coinbase value, and an Ed25519-signed receipt suitable for Stratum V2 Job Declaration use.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method",
    "bodyType",
    "body"
   ],
   "properties": {
    "body": {
     "type": "object",
     "properties": {}
    },
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "POST"
     ],
     "type": "string"
    },
    "bodyType": {
     "enum": [
      "json",
      "form-data",
      "text"
     ],
     "type": "string"
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "mode": "live_cached",
  "txids": [
   "81c97a6c5b98a1019095de132727cda868694fb5d92534ebb07e475619e38325"
  ],
  "height": 957401,
  "source": "core_v31_optimizer_cache",
  "receipt": {
   "alg": "Ed25519",
   "keyId": "08f55b7f4f76bd21",
   "present": true
  },
  "success": true,
  "txCount": 4000,
  "upliftBps": 677.5,
  "mempoolSize": 33741,
  "feeDeltaSats": 85137,
  "coinbaseValue": 313858787,
  "totalFeesSats": 1343458,
  "baselineFeeSats": 1258321,
  "baselineTxCount": 3500,
  "optimizedFeeSats": 1343458,
  "previousBlockHash": "00000000000000000000dbfaaa4541135bfcfe5928920609d213f621ef4ef8d9",
  "optimizerOnlyCount": 65
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/nativebtc-optimized-block-template-txid-list-76f12f9f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.nativebtc.org](https://www.zero.xyz/host/api.nativebtc.org/llms.txt)