The Bitcoin mempool is the waiting room for unconfirmed transactions. Satoshi API provides 5 mempool endpoints that analyze congestion, fee buckets, and individual transactions from your own Bitcoin Core node.
Five endpoints covering congestion analysis, raw stats, individual transaction lookup, and recent activity.
Full congestion analysis. Returns a congestion score, fee distribution broken into buckets (e.g. 1-5, 5-10, 10-25, 25-50, 50-100, 100+ sat/vB), the estimated minimum fee to enter the next block, total transaction count, and total size in virtual bytes. This is the primary endpoint for applications that need actionable mempool intelligence, not just raw numbers.
Raw mempool statistics from Bitcoin Core. Returns the number of unconfirmed transactions, total size in bytes, memory usage, minimum relay fee, and incremental relay fee. Lightweight and fast -- useful for monitoring scripts and dashboards.
Look up a specific unconfirmed transaction by its txid. Returns fee, virtual size, weight, time in mempool, ancestor and descendant counts, and whether the transaction signals replace-by-fee. Useful for tracking broadcast status and estimating confirmation time.
Returns every transaction ID currently in the mempool. Useful for syncing a local mempool mirror, building custom fee estimators, or detecting specific transactions without polling individual txids.
Recently added mempool entries. Shows the latest transactions to enter the mempool, ordered by arrival time. Useful for real-time transaction feeds, monitoring broadcast propagation, and detecting new activity.
Most Bitcoin APIs return raw getmempoolinfo output. Satoshi API adds analysis.
A single congestion_level field tells your application whether the mempool is calm, busy, or severely congested. No need to interpret raw byte counts or transaction counts yourself.
Transactions are grouped by fee rate into buckets (1-5, 5-10, 10-25, 25-50, 50-100, 100+ sat/vB). This shows fee distribution at a glance -- critical for wallets choosing fee rates and for dashboards visualizing network conditions.
The next_block_min_fee field estimates the lowest fee rate likely to be included in the next block. Combine with the fee buckets to give users precise guidance on what to pay.
Bitcoin Core's RPC returns numbers. Satoshi API returns decisions. Instead of "there are 45,000 transactions totaling 280 MB," you get "congestion is high, minimum next-block fee is 22 sat/vB, 60% of transactions are paying under 10 sat/vB."
Query the public instance or your own self-hosted API.
# Get mempool congestion analysis
curl https://bitcoinsapi.com/api/v1/mempoolSample response:
{
"data": {
"congestion_level": "moderate",
"congestion_score": 0.45,
"tx_count": 32841,
"total_size_bytes": 98523648,
"total_fee_btc": 1.847,
"next_block_min_fee": 12.5,
"fee_buckets": {
"1-5": 8921,
"5-10": 7403,
"10-25": 9182,
"25-50": 4856,
"50-100": 1834,
"100+": 645
}
},
"meta": {
"cached": false,
"request_id": "a1b2c3d4"
}
}The congestion_score ranges from 0.0 (empty mempool) to 1.0 (severely congested). The fee_buckets object shows how many transactions fall into each fee rate band, measured in sat/vB.
The mempool tells you what's waiting. The fee endpoints tell you what to pay. Together, they give a complete view of network conditions.
The mempool endpoints show congestion and fee distribution among unconfirmed transactions. The fee estimation endpoints use Bitcoin Core's estimatesmartfee to recommend fee rates for specific confirmation targets (e.g. "confirm within 3 blocks"). Applications that need both situational awareness and actionable fee guidance should use both endpoint groups together.
Smart fee recommendations for 1-1008 block confirmation targets, with confidence levels and fee rate history. Pairs naturally with mempool data for complete network condition monitoring.
Mempool queries reveal what you care about. Self-hosting keeps that private.
When you query mempool.space, BlockCypher, or any hosted service for a transaction ID, that service learns you are interested in that specific transaction. They can correlate your IP address with the txid, build a profile of which transactions you track, and potentially link that to your identity.
With a self-hosted Satoshi API instance, every mempool query goes directly to your own Bitcoin Core node over localhost. No third party sees your lookups. No IP logging. No usage analytics you didn't consent to. This is particularly important for wallet developers, exchanges, and anyone handling transaction monitoring at scale.
Try the public API instantly, or self-host for zero-leakage mempool access from your own node.