Twelve Data API

Twelve Data offers multi-asset market data with server-side technical indicators. Good free tier for prototypes.

Key endpoints

Endpoint	Description	Free tier
GET /time_series	OHLCV time series	✅
GET /quote	Real-time quote	✅
GET /price	Latest price only	✅
GET /symbol_search	Search symbols	✅
GET /technical_indicators	100+ indicators (SMA, RSI, MACD…)	✅
GET /profile	Company profile	❌ (Grow+)
GET /dividends	Dividend history	❌ (Grow+)
GET /earnings	Earnings data	❌ (Grow+)
GET /income_statement	Financial statements	❌ (Pro+)
GET /forex_pairs	Forex symbol list	✅

Python example: time series

import httpx

API_KEY = "your_twelvedata_key"
BASE = "https://api.twelvedata.com"
HEADERS = {"Authorization": f"apikey {API_KEY}"}

def get_time_series(symbol: str, interval: str = "1day", outputsize: int = 30) -> dict:
    """OHLCV time series. Header auth recommended."""
    resp = httpx.get(
        f"{BASE}/time_series",
        params={"symbol": symbol, "interval": interval, "outputsize": outputsize},
        headers=HEADERS, timeout=15,
    )
    resp.raise_for_status()
    data = resp.json()
    if data.get("status") == "error":
        raise ValueError(data.get("message"))
    return data

# Example
ts = get_time_series("AAPL", interval="1day", outputsize=5)
for bar in ts["values"]:
    print(f"{bar['datetime']}: close ${bar['close']}")

Python example: real-time quote

def get_quote(symbol: str) -> dict:
    resp = httpx.get(f"{BASE}/quote", params={"symbol": symbol}, headers=HEADERS, timeout=10)
    resp.raise_for_status()
    return resp.json()

# Example
q = get_quote("AAPL")
print(f"{q['name']}: ${q['close']} ({q['percent_change']}%)")

Python example: technical indicator (RSI)

def get_rsi(symbol: str, interval: str = "1day", time_period: int = 14) -> dict:
    """Server-side RSI calculation. No local computation needed."""
    resp = httpx.get(
        f"{BASE}/rsi",
        params={"symbol": symbol, "interval": interval, "time_period": time_period},
        headers=HEADERS, timeout=15,
    )
    resp.raise_for_status()
    return resp.json()

# Example
rsi = get_rsi("AAPL")
latest = rsi["values"][0]
print(f"AAPL RSI(14): {latest['rsi']}")

Python example: symbol search

def search_symbols(query: str) -> list[dict]:
    resp = httpx.get(f"{BASE}/symbol_search", params={"symbol": query}, headers=HEADERS, timeout=10)
    resp.raise_for_status()
    return resp.json().get("data", [])

# Example
for s in search_symbols("tesla")[:3]:
    print(f"{s['symbol']}: {s['instrument_name']}")

Notes:

• Free: 800 credits/day, 8 credits/min — each endpoint has a credit weight
• Fundamentals (/profile, /dividends) need Grow ($79/mo); financial statements need Pro ($229/mo)
• WebSocket: wss://ws.twelvedata.com/v1/quotes/price?apikey=KEY — subscribe with {"action":"subscribe","params":{"symbols":"AAPL"}}
• Demo key apikey=demo works for limited testing