Best Unified Market Data APIs for Quants

Disclosure: we build AuraStream, one of the APIs compared here. We have tried to be fair, including a section on when AuraStream is the wrong choice. Prices and features were checked on each vendor’s own website on 22 October 2026; they change often, so confirm before you buy.

Most quant research pulls from several places at once: prices from a broker or exchange, macro series from a central bank, crypto from an exchange API. Each source has its own authentication, ticker format, rate limits and response shape. A unified market data API puts many of those sources behind one interface, so the code that fetches data stays the same when the source changes.

There are two different products sold under that idea, and it helps to separate them:

• Aggregators route your request to the original provider and return the result in one format. AuraStream and OpenBB work this way. You often bring your own key for paid upstream sources.
• Single-source vendors license data from exchanges and other sources and sell it as their own feed. Alpha Vantage, Twelve Data and Massive (formerly Polygon.io) work this way. One contract, one licence, but you get only what that vendor carries.

Comparison

Sources: AuraStream docs, AuraStream plans, OpenBB ODP docs, OpenBB pricing, Alpha Vantage premium, Twelve Data pricing, Massive pricing. Checked 22 October 2026.

Short take on each

AuraStream

One POST endpoint for every source: change the source field and the rest of the request and the response format stay the same. Public sources (Binance, Bybit, Kraken, Yahoo) need no extra key; for Oanda, Alpaca, Polygon/Massive, FRED and Finnhub you pass your own credentials in the request. Best for researchers who mix asset classes (for example FX, crypto and macro in one study) and want one client and one response format instead of five.

OpenBB

A free, open-source Python framework. Since version 5 each provider has its own namespace, and several commercial providers from earlier versions were removed, so it is now strongest on public macro and government data. Best for Python users who want something free and self-hosted and are happy to write their own provider extensions.

Alpha Vantage

Very broad coverage for a low price, including economic indicators, fundamentals and news. The free tier (25 requests a day) is only enough for trying it out. Best for low-volume, mostly end-of-day work across many asset classes.

Twelve Data

Global equities, FX and crypto with WebSocket streaming and an official Python SDK. Separate plans for business use and display rights. Best for applications that need streaming prices across international markets at mid-range cost.

Massive (formerly Polygon.io)

Deep US equities and options data, real-time feeds and bulk flat files. Polygon.io rebranded as Massive in October 2025; existing keys keep working. Best for US-focused strategies that need tick-level history or real-time data.

Where AuraStream is stronger

• One request format across asset classes. FX, crypto, US equities, global ETFs, macro series and historical futures all come through the same endpoint and the same response shape. A cross-asset study needs one client, not five.
• Order book snapshots and funding rates. Oanda order books and Binance funding rates are available through the same call as prices. None of the four alternatives above list broker order book data.
• Use the provider accounts you already have. If you already pay for Polygon/Massive or trade through Oanda or Alpaca, pass your own credentials and keep your existing data rights, instead of paying twice.
• Low entry price for multi-source access. The paid plan is $30 a month with every source included; the free plan has every source too, with 500 calls a month.
• Built by a quant team for research. AuraStream is the data layer we use in our own strategy work, so it is designed around backtesting workflows rather than dashboards.

When AuraStream is not the right choice

• You need real-time streaming. AuraStream has no WebSocket feed and is not built for live tick data. Use Twelve Data, Massive, or the exchange’s own stream.
• You only use one source. If all your data comes from FRED, or only from Binance, call that API directly. It is free, and you skip a layer.
• You need tick-level history at scale. Bulk downloads of years of trades and quotes are better served by flat files from a specialist such as Massive.
• You need redistribution or display rights. AuraStream passes data through from upstream providers under their terms. If you plan to show data to your own customers, buy a licence that covers it.
• You want open source and self-hosting. OpenBB’s framework is free and runs on your machine.
• You need a contractual SLA and enterprise support. Larger vendors offer business plans with service levels; AuraStream is a small team.

Python example: three sources, one client

This pulls US ETFs from Yahoo, Bitcoin from Bybit and the US CPI index from FRED, then lines them up in one DataFrame. Only FRED needs an extra key (free from the St. Louis Fed).

import requests
import pandas as pd

URL = "https://api.aurastream.unbiased-alpha.com/timeseries"
HEADERS = {"x-api-key": "YOUR_AURASTREAM_API_KEY"}


def fetch(source, tickers, interval="1d", credentials=None):
    resp = requests.post(URL, headers=HEADERS, timeout=120, json={
        "tickerlist": tickers,
        "start": "2025-01-01",
        "end": "2025-12-31",
        "interval": interval,
        "source": source,
        "credentials": credentials,
    })
    resp.raise_for_status()
    data = resp.json()  # {ticker: {timestamp: {"Open": ..., "Close": ...}}}
    closes = {}
    for ticker, rows in data.items():
        s = pd.Series({ts: float(bar["Close"]) for ts, bar in rows.items()})
        s.index = pd.to_datetime(s.index)
        closes[ticker] = s.sort_index()
    return pd.DataFrame(closes)


etfs = fetch("yahoo", ["SPY", "TLT", "GLD"])
btc = fetch("bybit", ["BTCUSDT"])
cpi = fetch("fred", ["CPIAUCSL"], interval="1m", credentials={"key": "YOUR_FRED_KEY"})

prices = etfs.join(btc, how="left")
returns = prices.pct_change().dropna()
print(returns.corr().round(2))
print(cpi.tail())

Each call counts once against your allowance however many tickers it contains, so put several tickers in one request.

FAQ

What is a unified market data API?

An API that gives you data from several providers through one interface, with one authentication method and one response format. Some do it by routing to the original providers (aggregators), others by licensing the data and serving it themselves.

Is AuraStream real-time?

No. It is a request/response API for historical and recent time series. For live streaming, use a WebSocket feed from a vendor or exchange.

Do I need my own provider keys with AuraStream?

For some sources. Binance, Bybit, Kraken and Yahoo work without one. Oanda, Alpaca, Polygon/Massive, FRED and Finnhub need your own credentials, passed in the request.

Which of these APIs has a free tier?

All five. AuraStream: 500 calls a month. OpenBB’s framework is free software. Alpha Vantage: 25 requests a day. Twelve Data: 800 credits a day. Massive: 5 calls a minute with end-of-day data.

Which ones work with Claude or ChatGPT through MCP?

All five do. OpenBB, Alpha Vantage, Twelve Data and Massive publish official MCP servers, and AuraStream’s is open source on GitHub; our MCP guide shows how to connect it to Claude or ChatGPT.

Can I use the data in a product I sell?

Check the licence. Twelve Data and Massive sell separate business plans for display and distribution. Data from aggregators like AuraStream and OpenBB stays under the upstream provider’s terms.