Metra

Website | API Docs

Metra is a unified, real-time aggregation layer for cryptocurrency market data. It connects multiple upstream exchange WebSockets, normalizes the raw execution data into a standardized schema, and rebroadcasts it to downstream clients via Server-Sent Events (SSE).

The project abstracts away the complexity of managing multiple WebSocket connections, exchange-specific parsing, connection age management, and heartbeat maintenance. It is designed to serve as a firehose for quantitative analysis, algorithmic trading bots, and data archival systems.

The firehose API is free, and relies on the generous public data streams offered by the exchanges.

Features

• Unified Schema: Consumes the formats from Binance and Bitstamp and outputs a consistent JSON structure.
• Zero Configuration: No API keys or authentication required.
• Traffic Shaping: Built-in throttling to control downstream message rates (e.g., limiting high-frequency streams to 100ms updates).
• Lightweight Explorer: Includes a built-in web dashboard for inspecting live feeds, built with Go Templ, Mithril.js, and Tailwind CSS v4.

API Documentation

The primary interface is a streaming REST endpoint over SSE.

Endpoint

GET /stream/{exchange}/{pair}/{event}

Parameters

Parameter	Type	Description
exchange	Path	Upstream source. Supported: binance, bitstamp.
pair	Path	Trading pair symbol (e.g., btcusdt, ethusd).
event	Path	Data type. Currently supported: trade.
throttle	Query	(Optional) Minimum interval between messages (e.g., 100ms, 1s, 2s).

Example

# Stream Bitcoin trades from Binance, capped at one trade every 100ms
curl -N "https://metra.sh/stream/binance/btcusdt/trade?throttle=100ms"

Running Locally

Prerequisites

• Go 1.25+
• Tailwind CSS CLI (v4+)
• Templ

Build & Run

# Generate templates
templ generate

# Build CSS
./tailwindcss -i web/static/css/input.css -o web/static/css/style.css --minify

# Compile and Run
go build .
./metra

The server will start on port 8080.

Docker

A multi-stage Dockerfile is provided for production deployments.

docker build -t metra .
docker run -p 8080:8080 metra

Roadmap

The current implementation focuses on spot trade normalization. Future development will target:

1. Expanded Coverage: Integration with Coinbase, Kraken, and Bybit.
2. Data Depth: Support for Level 2 (Orderbook) and Ticker events.
3. Transport: Optional gRPC/Protobuf streaming for high-throughput internal consumption. Maybe downstream WS too?
4. Analytics: Maybe? Be nice to have some real-time sliding window aggregations (VWAP, OHLCV).

Contributions

For anyone interested in contributing, please read contribute.md first.