Mempool and fees

The node's mempool as btcintel mirrors it, the projected next blocks, replacements and fee estimates — projection and node figures kept apart — and the live stream of all of them.

Generated from openapi.yaml (Btcintel native API 0.1.0). Every hash is canonical display order; every answer carries the index and node heights; errors use one envelope — see Semantics.

GET /v1/mempool — Recent mempool transactions
GET /v1/mempool/txids — Txids of the mempool sample
GET /v1/mempool/stats — Whole-mempool statistics
GET /v1/mempool/projected — Projected blocks (mempool engine, ADR-0003)
GET /v1/mempool/replacements — Recent RBF replacements (mempool engine, ADR-0003)
GET /v1/fees/estimates — Fee recommendations (mempool engine, ADR-0003)
GET /v1/stream — Live updates (server-sent events, spec M1)

GET `/v1/mempool`

Recent mempool transactions

Newest 500 entries with fee, vsize and first sighting; totals live in /v1/mempool/stats.

Response `200`

Mempool sample.

schema

array of MempoolTx

txid string — Canonical display byte order.
fee_sat integer
vsize integer
fee_rate number — sat/vB, 2 decimals.
first_seen string (date-time)

Example

curl y jq, en cualquier shell.

curl -s https://api.btcintel.io/v1/mempool | jq

GET `/v1/mempool/txids`

Txids of the mempool sample

Response `200`

Canonical txids.

schema

array of string

Example

curl y jq, en cualquier shell.

curl -s https://api.btcintel.io/v1/mempool/txids | jq

GET `/v1/mempool/stats`

Whole-mempool statistics

Response `200`

Count, vsize, total fee and fee-rate histogram over the full mirrored mempool.

schema

count integer
vsize integer
total_fee integer
fee_histogram array of array of number — [fee_rate_bucket_floor_satvb, vsize] pairs, high to low.

Example

curl y jq, en cualquier shell.

curl -s https://api.btcintel.io/v1/mempool/stats | jq '{count, vsize, total_fee}'

GET `/v1/mempool/projected`

Projected blocks (mempool engine, ADR-0003)

The mempool packed into template-sized blocks by effective (ancestor package) fee rate — the getblocktemplate approach. Up to 8 blocks described individually; the rest aggregated under remaining.

Response `200`

Projection snapshot (recomputed every ~2 s).

schema

blocks array of ProjectedBlock
- ntx integer
- vsize integer
- weight integer
- total_fee_sat integer
- fee_range array of number — [lowest, highest] effective sat/vB in this slice.
- median_rate number — vsize-weighted median of package rates; absent on remaining.
remaining one of — Aggregate past the detailed horizon; fee_range uses base rates there.
- ProjectedBlock
  - ntx integer
  - vsize integer
  - weight integer
  - total_fee_sat integer
  - fee_range array of number — [lowest, highest] effective sat/vB in this slice.
  - median_rate number — vsize-weighted median of package rates; absent on remaining.
- null
remaining_blocks integer — ceil(remaining weight / block budget).
tx_count integer
as_of string (date-time)

Errors

501 — The mempool engine is not enabled on this deployment (BITCOIN_ZMQ_SEQUENCE unset).
503 — Engine bootstrapping; retry shortly.

Example

curl y jq, en cualquier shell.

curl -s https://api.btcintel.io/v1/mempool/projected | jq '{remaining_blocks, tx_count, as_of}'

GET `/v1/mempool/replacements`

Recent RBF replacements (mempool engine, ADR-0003)

Replacements observed by outpoint conflict — independent of BIP125 signaling, so full-RBF replacements are included. Newest first.

Parameters

Name	In	Type	Description
`limit`	query	integer · ≤ 200 · default 25	—

Response `200`

Replacement events.

schema

array of Replacement

txid string — Canonical display byte order.
fee_sat integer
vsize integer
rate number — sat/vB.
replaced array of object
- txid string — Canonical display byte order.
- fee_sat integer
- vsize integer
- rate number
at string (date-time)

Errors

501 — The mempool engine is not enabled on this deployment (BITCOIN_ZMQ_SEQUENCE unset).
503 — Engine bootstrapping; retry shortly.

Example

curl y jq, en cualquier shell.

curl -s 'https://api.btcintel.io/v1/mempool/replacements?limit=25' | jq

GET `/v1/fees/estimates`

Fee recommendations (mempool engine, ADR-0003)

Derived from the projection's vsize-weighted medians, floored at the node's mempool minimum and monotonic (fastest ≥ half_hour ≥ hour ≥ economy ≥ minimum). The node's estimatesmartfee (targets 1/3/6) rides along under node for comparison — never blended in.

Response `200`

Recommendations in sat/vB.

schema

fastest number — Median of projected block 1, sat/vB.
half_hour number — Median of projected block 3.
hour number — Median of projected block 6.
economy number — Median of the last detailed block.
minimum number — Node mempool floor (mempoolminfee).
node object — estimatesmartfee sat/vB by target ("1", "3", "6"), for comparison.
basis object
- tx_count integer
- vsize integer
as_of string (date-time)

Errors

501 — The mempool engine is not enabled on this deployment (BITCOIN_ZMQ_SEQUENCE unset).
503 — Engine bootstrapping; retry shortly.

Example

curl y jq, en cualquier shell.

curl -s https://api.btcintel.io/v1/fees/estimates | jq '{fastest, half_hour, hour}'

GET `/v1/stream`

Live updates (server-sent events, spec M1)

One server-sent event stream of the tip, the mempool, the projection, the fees and the state of up to 16 transactions, from the mempool engine (ADR-0003). Each event's data is one JSON object (the Stream* schemas) whose at is when the engine applied the change. - The stream opens with retry: 3000 and one snapshot per topic and per transaction whose state is known. A transaction the engine does not know (never seen, or in a block before the stream opened) has none: read GET /v1/tx/{txid}. - Then block, mempool, projected and fees (each only when it changed, at most one per reprojection) and tx. - Every event has an id of <boot>-<seq>. There is no replay: Last-Event-ID is ignored and a reconnect gets a fresh snapshot. - A comment line goes out every 15 s. The stream closes after six hours, or once the client falls 16 events behind, and the client reconnects. - Concurrent streams per caller: t0 2, t1 4, t2 and t3 10, t4 50, under a server-wide cap. Opening a stream counts as one request of the quota; events do not.

Parameters

Name	In	Type	Description
`topics`	query	string	Comma-separated: block, mempool, projected, fees. A stream needs topics or tx (400 otherwise).
`tx`	query	string	Up to 16 comma-separated txids.

Response `200`

The stream. Events: snapshot (StreamSnapshot), block (StreamBlockEvent), mempool (StreamMempoolEvent), projected (StreamProjectedEvent), fees (StreamFeesEvent), tx (StreamTxEvent).

Headers: Cache-Control, X-Accel-Buffering

schema

array of one of

Errors

400 — Malformed input (invalid_input).
429 — quota_exceeded: the caller or the server holds as many streams as allowed (Retry-After: 30), or the caller's request quota ran out.
501 — not_configured: the mempool engine is not enabled (BITCOIN_ZMQ_SEQUENCE unset), or the stream is off (STREAM_MAX_CLIENTS=0).
503 — Engine bootstrapping; retry shortly.

Example

Solo curl: -N imprime cada evento según llega. Detenlo con Ctrl-C.

curl -sN 'https://api.btcintel.io/v1/stream?topics=block,fees'

Mempool and fees

GET /v1/mempool

Response 200

Example

GET /v1/mempool/txids

Response 200

Example

GET /v1/mempool/stats

Response 200

Example

GET /v1/mempool/projected

Response 200

Errors

Example

GET /v1/mempool/replacements

Parameters

Response 200

Errors

Example

GET /v1/fees/estimates

Response 200

Errors

Example

GET /v1/stream

Parameters

Response 200

Errors

Example

GET `/v1/mempool`

Response `200`

GET `/v1/mempool/txids`

Response `200`

GET `/v1/mempool/stats`

Response `200`

GET `/v1/mempool/projected`

Response `200`

GET `/v1/mempool/replacements`

Response `200`

GET `/v1/fees/estimates`

Response `200`

GET `/v1/stream`

Response `200`