BTCRouter: Real-Time Bitcoin Fee Estimation Without a Full Node

I built BTCRouter because most Bitcoin wallets estimate fees with a simple multiplier — "slow / medium / fast" — and it's often catastrophically wrong. When the mempool is empty, you overpay. When it's full, you underpay and wait 3 days.

The Problem with Current Fee Estimation

Full Bitcoin Core nodes solve this properly, but require:

150GB+ storage
All-day initial sync
Constant upkeep

Too heavy for embedded devices, mobile apps, or quick scripting.

BTCRouter uses Blockstream's Electrum API instead — no node required, works from any machine.

What BTCRouter Does

A Python library for real-time Bitcoin intelligence:

Fee Estimation — 4 tiers (economy/normal/fast/instant) from live mempool data
Congestion Analysis — score 0–100 of on-chain demand with actionable recommendations
UTXO Optimization — greedy selection minimizing inputs + fees
RBF Simulation — model Replace-By-Fee scenarios
Privacy Scoring — grade your UTXO set based on address reuse and amount patterns

How Fee Estimation Works

Blockstream returns percentile fee data at different block targets:

Tier	Block Target	Typical Wait
Economy	24 blocks (~4 hrs)	~30 min
Normal	6 blocks (~1 hr)	~1 hour
Fast	3 blocks (~30 min)	~10 min
Instant	1 block	next block

UTXO Selection Algorithm

Uses greedy selection by value — sort UTXOs descending, pick largest until total covers target + fee. Minimizes input count → smaller transaction → lower fees.

Privacy Scoring

Your UTXO set leaks privacy in subtle ways:

Address reuse — deduct 10pts per duplicate
Round amounts — many UTXOs at exact multiples of 100k sats (likely exchange batches)
One dominant UTXO — >90% of value in single UTXO (easy to correlate)