BitcoinDatabase.com
How it works
Bitcoin API Block explorer API Address lookup Historical data API On-chain data Transaction API Bitcoin data API Wallet tracker On-chain metrics Rich list Address balance API Query with SQL Crypto AML API UTXO data Blockchain API Flow analysis Node API Webhook API Price API Transaction monitoring Mempool API RPC API xpub balance API See all →
Glassnode alternative Dune alternative Blockchair alternative Chainalysis alternative BlockCypher alternative Chainstack alternative Blockchain.com API alternative Mempool.space alternative CoinAPI alternative TRM Labs alternative Whale Alert alternative CoinGecko alternative CoinMarketCap alternative Blockdaemon alternative Xverse alternative BigQuery alternative Bitquery alternative TimechainIndex alternative CryptoQuant alternative
Docs Pricing Blog Contact

Query the chain · Mempool API

Bitcoin mempool API for unconfirmed transactions and fee estimation

The mempool is where a Bitcoin transaction lives before it is mined, and it is what you read to estimate a fee or watch for an incoming payment. BitcoinDatabase exposes the live mempool over a clean REST API: list unconfirmed transactions, look up a specific txid before it confirms, check an address for pending activity, and pull current fee rates by target confirmation window so you attach the right fee instead of guessing.

or try it below ↓

REST API · SQL · dashboards · indexed from genesis

Query Console
btc
try:

Hit Run to query the fully-indexed Bitcoin blockchain.

BTC

30-day trend

informational on-chain data · not financial advice

REST API · SQL · dashboards, one indexed dataset. Querying the indexed Bitcoin blockchain ...

Run it without hosting Bitcoin Core, syncing the chain, or hitting the rate limits of a shared public endpoint. The same indexed data, confirmed and unconfirmed, is queryable in SQL and dashboards, so your wallet, payment flow or dashboard reads from one source. Informational on-chain data only, not financial advice.

REST API SQL DASHBOARDS WEBHOOKS CSV EXPORT

Indexed from genesis queryable in seconds

On-chain data not financial advice

Why it works

What you get with Mempool API

Live unconfirmed data

List mempool transactions, look up a txid before it confirms, and check any address for pending activity, so you react the moment a payment broadcasts rather than after a block.

Fee estimation built in

Pull current fee rates by target confirmation, from next-block to economy, computed from real mempool state, so your wallet or service attaches a fee that gets mined without overpaying.

No node, no rate wall

Skip running Bitcoin Core and skip the throttling of a shared public mempool endpoint. One API key gives you production access to confirmed and unconfirmed data alike.

What it handles

The indexed Bitcoin chain, queryable your way

Look up an address, a transaction, a UTXO, the rich list or an on-chain metric, by REST API, SQL or dashboard. The same authoritative data, reconciled block-by-block against the canonical chain, without running a node.

  • List current unconfirmed mempool transactions
  • Look up a transaction by txid before it confirms
  • Estimate fees by target confirmation window
  • Watch an address for incoming pending payments
  • Query the same data via REST, SQL or dashboards
GET /v1/address/{addr} query result
200 · JSON 
{
  "address": "bc1qxy2k…l0wdv8",
  "balance_btc": 68432.10,
  "balance_usd": 4612165420,
  "tx_count": 1284,
  "unspent_outputs": 37,
  "first_seen": "2014-02-09"
}
indexed from genesis · to the satoshi ✓ reconciled block-by-block

Why BitcoinDatabase

One platform, queryable three ways

Not a raw node to sync, not an indexer to build, and not five vendors to stitch together. The fully-indexed Bitcoin blockchain, available as a REST API, as SQL, and as dashboards, on one authoritative dataset.

REST API

Typed JSON for addresses, transactions, balances, UTXOs and metrics. Drop it into apps, wallets, explorers and agents with curl, Python or any HTTP client.

SQL access

Run SQL directly against the indexed Bitcoin dataset for ad-hoc analysis, cohorts and exports, the same data the API and dashboards read from.

Compliance-first

Informational on-chain data and analytics only. Entity labels and flow tracing are framed as tooling to support a regulated team's own review, not accusations.

Good questions

Questions about Mempool API

It returns live mempool state: the set of unconfirmed transactions, a lookup for any pending txid, pending activity for an address, and current fee-rate estimates by target confirmation window. It reads from our indexed view of the chain, so you get confirmed and unconfirmed data from one endpoint without running a node.
Fee estimation reads the transactions waiting in the mempool and the fee rate each is paying, then infers the sat-per-vByte needed to get mined within a target number of blocks. A busier mempool pushes the next-block rate up. BitcoinDatabase computes this for you so you attach a fee that confirms without overpaying.
Query the mempool and filter on output value, then apply a second filter that most feeds skip: exclude the value returning to an address that already funded the transaction. Bitcoin spends whole outputs, so a pending transfer showing 12 BTC is frequently a wallet sending change back to itself rather than paying anyone.
Because there is no single mempool. Every node keeps its own pool of unconfirmed transactions, shaped by when it came online, its memory limit, its minimum relay fee and which peers reached it first. Two explorers can both be correct and still disagree on what is pending, which is why a transaction can be missing from one and visible on another.
Two different ways, and they move independently. Transaction count is how many transactions are waiting. Byte size is the total virtual size of those transactions, usually reported in vB or MB, and it is the figure that predicts confirmation delay, because miners fill roughly four million weight units per block regardless of how many transactions that takes.
Yes. Check the address against mempool state and you see pending inputs and outputs touching it the moment they broadcast, ahead of any block. That is what a payment flow needs in order to show a customer that funds arrived, while still waiting for confirmations before treating the payment as final.
Nodes evict the lowest fee-rate transactions when their pool hits its memory limit, and many drop entries after roughly two weeks. The transaction is not invalid, it is simply no longer being relayed, so the coins remain unspent and the sender can rebroadcast it or replace it with a higher fee.
Read every Bitcoin API question

Explore more

More ways to query Bitcoin with BitcoinDatabase

Bitcoin exchange flow API

Measure bitcoin moving into and out of exchanges: inflows, outflows and net flow.

Learn more

Bitcoin Whale Alert API

Detect large bitcoin transactions and whale moves from the indexed chain, on your own thresholds.

Learn more

On-chain data

The raw on-chain truth: addresses, balances, UTXOs and flows, queryable.

Learn more

On-chain metrics

Active addresses, realized cap, SOPR, HODL waves and exchange flows.

Learn more

Bitcoin flow analysis

Trace how funds move between addresses, clusters and entities.

Learn more

Bitcoin transaction volume

Raw, change-adjusted and entity-adjusted on-chain volume series from the indexed chain.

Learn more
See every use case See pricing Back to the Bitcoin API

Stop running a node. Just query Bitcoin.

Run your first query now and get on-chain data back by REST API, SQL or dashboard, indexed from the genesis block. Informational on-chain data only, not financial advice.

See pricing

Indexed from genesis · REST · SQL · dashboards · addresses, transactions, UTXOs, metrics