Building a crypto trading bot is a real engineering project — here's a practical overview of how people actually put one together.
Core architecture (the parts every bot has)
- Market data feed — pull live prices/order books. Free options: Binance/Bybit/Coinbase WebSocket APIs (real-time, no polling lag), CoinGecko/DexScreener for REST snapshots (fine for slower strategies).
- Strategy engine — the logic that decides when to buy/sell. This is where most of the work lives.
- Execution layer — places orders via the exchange's REST API, handles the order lifecycle (submitted → filled → cancelled), and checks fills against your expectations.
- State store — a database (SQLite is fine to start) tracking positions, orders, PnL, and bot status so it survives crashes.
- Risk controls — position sizing, per-trade loss limits, max open positions, and a kill switch. This layer is non-negotiable for a real account.
Strategy types (pick one, master it)
- Market making — place bid/ask quotes around the mid price, earn the spread. Needs deep liquidity and low fees; mostly viable on high-volume pairs.
- Arbitrage — profit from price differences between venues. But fast bots and cross-exchange infrastructure; spread is often tiny.
- Momentum / trend-following — buy on breakout, sell on reversal. Uses indicators like moving-average crosses or RSI. Most accessible for beginners.
- Grid trading — place laddered buy/sell orders in a range. Simple, mechanical, popular for ranging markets.
Tech stack
- Python is the default:
ccxt (one library wrapping dozens of exchanges) + pandas for analysis + websocket-client. If you need speed (arbitrage), Go or Rust.
- Backtest before touching real money —
backtrader or vectorbt let you replay a strategy on historical data. Expect most strategies to fail backtesting; that's normal, it saves you money.
The hard truth people don't hear first
- A winning strategy doesn't stay winning — edge decays as others copy it.
- Fees and slippage are usually larger than the expected edge on retail-scale capital. Test your math net of fees.
- Overfitting is the #1 killer: a strategy tuned perfectly to the past rarely works forward.
- Bots run 24/7 and fail in unglamorous ways — API rate limits, disconnections, exchange maintenance, a coin that jumps 20% during a bot outage.
- Never store API keys in your code or share them; use read-only keys where possible and restrict them to trading (no withdrawal permission).
If you want, I can point you at where to actually run a bot or a trading platform (DEXs and trading apps you can connect to), or pull up live data on specific coins if you're thinking about what to trade. Want me to look into either?