---
name: obol-x402.fly.dev
description: obol-x402.fly.dev provides signed Bitcoin mempool data via two endpoints: a lightweight next-block fee estimate and a fuller congestion snapshot. Both responses include Ed25519-signed attestations for cryptographic verification. No streaming, historical, or non-Bitcoin chain data is available.
host: obol-x402.fly.dev
---

# obol-x402.fly.dev

OBOL is a narrow Bitcoin fee-oracle service targeting agents that need authoritative, verifiable fee data before constructing or timing Bitcoin transactions. It serves use cases where a signed, point-in-time fee estimate is required — either a minimal sat/vB figure or a richer congestion snapshot with backlog and broadcast advice. It does not cover EVM chains, historical analysis, or streaming feeds.

## When to use this host

Use this host when an agent needs a signed, verifiable Bitcoin fee estimate or congestion check before constructing or broadcasting a Bitcoin transaction. Prefer fetch-btc-next-block-fee for minimal overhead when only a sat/vB figure is needed. Prefer fetch-btc-congestion-snapshot when broadcast timing decisions require backlog depth, congestion tier, or fee-spike context. Do not use this host for EVM or non-Bitcoin chain fee estimation, historical fee trend analysis, or real-time streaming mempool data — those use cases require a different provider. This host has no inputs on either skill, so it cannot be parameterized for specific fee targets or confirmation windows.

## Capabilities

### Bitcoin Fee Estimation

Provides current Bitcoin next-block fee rates and mempool congestion data, both with cryptographic attestations, enabling agents to make informed transaction timing and fee-setting decisions.

- **`fetch-btc-next-block-fee`** — Returns the current Bitcoin next-block fee estimate in sat/vB along with an Ed25519-signed attestation for cryptographic verification.
- **`fetch-btc-congestion-snapshot`** — Returns a signed Bitcoin mempool congestion snapshot including congestion tier, fee-spike flag, next-block fee rate, mempool backlog estimates, and broadcast advice.

## Workflows

### Fee-Aware Transaction Timing

*Use when an agent needs to decide both the correct sat/vB fee to use and whether current network conditions warrant broadcasting immediately or waiting.*

1. **`fetch-btc-congestion-snapshot`** — Retrieve the full congestion snapshot to assess mempool backlog depth, fee-spike flag, and broadcast advice.
2. **`fetch-btc-next-block-fee`** — If broadcast is warranted, fetch the signed next-block fee estimate to use as the authoritative sat/vB value when constructing the transaction.

## Skill reference

### `fetch-btc-congestion-snapshot`

**OBOL Bitcoin Congestion Snapshot** — Returns a signed Bitcoin mempool congestion snapshot including congestion tier, fee-spike flag, next-block fee rate, mempool backlog estimates, and broadcast advice.

*Use when:* Use when an agent needs to decide whether to broadcast a Bitcoin transaction now or wait, based on current mempool congestion level, fee pressure, and backlog depth.

*Not for:* Do not use for real-time streaming mempool data or historical fee analysis; this is a single-shot snapshot. Not applicable for EVM or non-Bitcoin chain congestion checks.

**Returns:** Returns a data object with congestion tier, fee_spike flag, next_block_fee_sat_vb, mempool pending_tx/backlog_vsize/backlog_blocks_est, and broadcast_advice, plus an Ed25519 attestation block signed by OBOL.

**Example:** `GET https://obol-x402.fly.dev/v1/btc/congestion`

---

### `fetch-btc-next-block-fee`

**OBOL BTC Next Block Fee** — Returns the current Bitcoin next-block fee estimate in sat/vB along with an Ed25519-signed attestation for cryptographic verification.

*Use when:* Use when an agent needs a single authoritative sat/vB fee estimate for constructing or timing a Bitcoin transaction that must confirm in the next block, and requires a verifiable signed response.

*Not for:* Do not use for tiered fee estimates or full mempool data; use GET /pulse instead. Not suitable for EVM or non-BTC chain fee estimation.

**Returns:** Returns next_block_fee_sat_vb (integer sat/vB), congestion flags, a fee_spike boolean, and an Ed25519 attestation with pubkey and signature for verification.

**Example:** `GET https://obol-x402.fly.dev/v1/btc/fee/next-block`

---