Bitcoin data backend service. Fetches BTC prices from Binance (WebSocket) and Kraken (HTTP polling), stores them in PostgreSQL, and exposes a JSON API with WebSocket for live price streaming.

API

Endpoint	Description
`GET /api/price/ws`	WebSocket — sends HTML fragments with live price updates (HTMX-compatible)
`GET /api/price/latest`	Latest price as JSON
`GET /api/health`	Health check
`GET /api/price/day/:date`	Completed UTC BTC/USD daily OHLC, e.g. `/api/price/day/2020-01-01`
`GET /api/price/day?date=YYYY-MM-DD`	Same daily OHLC endpoint using a query parameter
`GET /api/swagger.json`	Swagger specification
`GET /swagger`	Interactive Swagger UI

Daily OHLC

Dates must be valid YYYY-MM-DD values strictly before today in UTC. Both kraken_day and kraken_day_history are checked before contacting Kraken. Missing recent candles are fetched from the OHLC API and saved in kraken_day. Older days outside Kraken's 720-candle window are calculated from paginated historical trades and saved in kraken_day_history for subsequent requests. Only trades in [00:00 UTC, next midnight UTC) contribute; VWAP is volume-weighted.

Example response (prices and volume are JSON numbers):

{"date":"2020-01-01","pair":"BTC/USD","open":7200,"high":7300,"low":7100,"close":7250,"vwap":7230.5,"volume":123.45,"trade_count":1000}

Errors are JSON: 400 for invalid, current or future dates, 404 for days without trades, and 502 for Kraken failures. Failed calculations are not cached. Historical requests wait for completion and can take several minutes; clients and reverse proxies need sufficiently long request timeouts. Kraken requests have a 60-second per-page timeout and historical pages are spaced one second apart.

The kraken_day_history migration runs automatically on application startup.

Quick Start

# Local dev (requires PostgreSQL)
cp .env.example .env   # edit JDBC_URL
make run               # starts on port 4100

# Docker
docker compose up -d   # starts on port 4101

Environment Variables

Variable	Default	Description
`BTCDATA_PORT`	`4100`	HTTP server port
`JDBC_URL`	—	PostgreSQL connection string
`CORS_ORIGIN`	`*`	Allowed origin for CORS headers

Data Sources

Binance — WebSocket trade stream (btcusdt@trade), throttled to 5s writes
Kraken hourly — OHLC candles polled at HH:01:00 UTC
Kraken daily — OHLC candles polled at 00:01:00 UTC

Tech Stack

Clojure · Kit · Undertow · Reitit · PostgreSQL · conman · Migratus