Guide / Market data

How to choose a market-data provider

A vendor-neutral framework — the seven things to check before you wire any OHLCV or quote feed into your stack.

6 min read · Updated quarterly

Picking a market-data provider looks like a pricing decision and turns out to be an architecture decision. The wrong choice surfaces months later as missing history, silently wrong bars, or a licensing letter. This guide is a checklist you can run against any provider — broker feed, commercial API, exchange-direct, or a free library — before you build on it. It deliberately makes no claims about any specific vendor's pricing or terms; those change constantly and you should confirm them at the source.

The seven checks

1. 1. Coverage.Match the provider to the asset classes, exchanges, and geographies you actually trade or analyze. A feed that's excellent for US equities can be thin on options chains, futures, or non-US listings. List your instruments first, then check support.
2. 2. History and granularity.Two numbers matter: how far back the data goes, and the smallest bar size at that depth. Intraday lookback windows vary enormously between providers and shrink as the interval gets finer. Confirm each provider's documented limits for the exact intervals you query — a backtest that silently truncates is worse than one that errors.
3. 3. Adjustments and quality. Ask how the provider handles corporate actions: splits, dividends, ticker changes, delistings. Unadjusted or inconsistently adjusted bars quietly corrupt backtests. Spot-check a few known split events before you trust a feed.
4. 4. Freshness.Decide what you need: real-time, delayed (often 15 minutes), or end-of-day. Delayed and EOD data is usually cheaper, licensed more loosely, and adequate for research and most analytics. Real-time carries higher cost and stricter terms — pay for it only where the use case demands it.
5. 5. Licensing and redistribution.The check people skip, and the one that bites. Permission to pull data for personal use is not permission to display it to your own users. Free and evaluation tiers very often prohibit redistribution entirely. Before building a product on a feed, read the provider's redistribution and commercial-display terms — and confirm in writing if anything is ambiguous.
6. 6. Cost model.Providers price on per-call, per-symbol, flat-rate, or tiered models, and the cheapest headline number is rarely cheapest in practice. Model your real query pattern — symbols times intervals times refresh frequency — including overage behavior.
7. 7. Reliability.Production data needs documented rate limits, an uptime/SLA commitment, and predictable failure behavior. The most dangerous failure mode is a feed that returns a silent gap instead of a clear error — your system can't tell "no trades" from "no data."

Provider categories

• Brokerage API feeds.Market data through your own brokerage connection; tied to your account and the broker's terms.
• Commercial data vendors. Paid APIs designed and licensed for redistribution and commercial display; the usual choice for serving data to your users at scale.
• Exchange-direct feeds. Data straight from the exchange; the most authoritative and typically the most rigorously licensed.
• Free and community libraries. Open-source wrappers and free endpoints; excellent for prototyping and personal research, but check the underlying terms of service before any commercial use.

See also

• Tracking institutional options flow - interpreting a structured public-tape signal.
• Why LLMs lose at trading - why the edge lives in deterministic tools, not the model.

Educational content, not investment or legal advice. Provider capabilities, pricing, and licensing terms change frequently and vary by plan — always verify the current terms on each provider's own site before relying on them.