API

The same numbers as the site, as JSON. Free, 60 requests a minute per key, cached ten seconds. Cite the source when you publish them.

Get a key

Sign this exact message with any wallet (the date is today in UTC; newlines are real newlines), then post it. The same wallet always gets the same key.

HL Book API key
0xYOURADDRESS
2026-09-21

curl -X POST https://hlbook.xyz/api/v1/keys \
  -H 'Content-Type: application/json' \
  -d '{"addr":"0x…","message":"HL Book API key\n0x…\n2026-09-21","signature":"0x…"}'
→ {"key":"hlb_…","rpm":60}

Endpoints

GET	Returns
/api/v1/market/BTC	Mark, tracked long/short, exchange open interest and funding, liquidation map buckets, top 50 holders with entry and liquidation
/api/v1/trader/0x…	Label, equity, net, gross, positions, fee-complete realized PnL where archived, equity curve, last 50 changes
/api/v1/liquidations	The latest cross-market map: notional within 2/5/10/20% per coin and side
/api/v1/cascade/BTC	Every position with a liquidation price, compact, for your own cascade math

curl https://hlbook.xyz/api/v1/market/BTC -H 'x-api-key: hlb_…'

Semantics

Every response carries asOf. Positions are as of each account’s last scan; liquidation prices drift with equity between scans.
Numbers are USD notional unless named otherwise. side is long or short; the cascade endpoint packs it as 0/1 to keep the payload small.
Errors are JSON with an error field; 401 for the key, 429 for the limit with Retry-After.
Higher limits and a firehose for desks: ask.