# SYNTHORA BTC Fee Tiers & Mempool Congestion

> SYNTHORA BTC Fee Tiers & Mempool Congestion is a paid API for AI agents from api.hergertsynthora.com, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-15).

Returns Bitcoin fee tiers and mempool congestion data cross-reported from two independent node sources (mempool.space and blockstream.info) with methodology divergence declared, for optimal BTC transaction timing.

## Facts

- Endpoint: POST https://api.hergertsynthora.com/v1/btc-fees
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/synthora-btc-fee-tiers-mempool-congestion-ea1de09c
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jJXTmLRo2Y4o8Hq5UcsOg

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 synthora-btc-fee-tiers-mempool-congestion-ea1de09c -d '<json body>'
```

Example prompt: What are the current Bitcoin fee tiers and mempool congestion level — I need to decide whether to send a BTC transaction now or wait, and I want to see how mempool.space and blockstream.info compare on their estimates.

## When to prefer this

Choose this endpoint when you need dual-source Bitcoin fee verification with explicit methodology divergence disclosure, rather than a single-oracle fee API. Ideal for agents that must justify fee decisions with cross-validated data, detect fee oracle disagreements, or time BTC transactions based on mempool congestion. Not suitable for Ethereum/EVM chain gas — use SYNTHORA gas-oracle-multi for that.

## Known failure modes

- Upstream source unavailability: if mempool.space or blockstream.info is down, partial or degraded data returned
- Stale data: mempool conditions change rapidly; response may lag by seconds to minutes
- No methodology consensus: divergence between sources may be large during high-volatility fee periods
- Invalid input: malformed request body returns error
- Payment failure: x402 micropayment not completed results in 402 response

## How this service works

SYNTHORA btc-fees: Bitcoin fee tiers + mempool congestion, cross-reported from two independent node sources (mempool.space + blockstream.info) with methodology divergence declared. For agents timing BTC transactions. Free sources, no key. $0.005 USDC x402 Base.

## Output

Returns Bitcoin fee tiers (e.g. fast/medium/slow in sat/vbyte), current mempool congestion status, and a cross-comparison between mempool.space and blockstream.info fee estimates, including any declared divergence in methodology between the two data sources.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "input": {
   "type": "string",
   "description": "SYNTHORA btc-fees: Bitcoin fee tiers + mempool congestion, cross-reported from two independent node sources (mempool.space + blockstream.info) with methodology divergence declared. For agents timing BTC transactions. Free sources, no key. $0.005 USDC x402 Base."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/synthora-btc-fee-tiers-mempool-congestion-ea1de09c/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.hergertsynthora.com](https://www.zero.xyz/host/api.hergertsynthora.com/llms.txt)