Free Options Data API: Coverage & Limits

Underlying, expiration, strike, call/put, multiplier, style, and listing status describe the instrument but not its market value.

Bid/ask NBBO, sizes, last trade, conditions, and timestamps are distinct. A last trade can be stale in an illiquid contract.

Greeks and implied volatility depend on the pricing model, interest rate, dividend assumptions, underlying price, and timestamp.

A backtest needs contracts, quotes, corporate actions, and underlying values as they were known then—not a reconstructed current chain.

Massive makes the free-versus-paid boundary visible at endpoint level. Contract discovery and selected reference operations can support symbol lookup and chain construction, while snapshots, complete quotes, deeper history, and real-time analytics vary by tier. Test the exact endpoint matrix instead of assuming the Free plan unlocks every field shown in the documentation.

Alpaca is practical when the same application uses paper trading, stock data, and option contract discovery. Its free plan can support prototypes and indicative workflows, but official OPRA real-time coverage belongs to a higher entitlement. That distinction matters for spread-sensitive screens and any interface that presents current bid and ask values.

Tradier exposes options-oriented endpoints in a brokerage ecosystem, which can reduce the gap between research and order workflows. Developers should confirm whether quotes are delayed or real-time for the account, which Greeks are provider-computed, and whether the intended use is personal, internal, or customer-facing.

Cboe's delayed quote interface is valuable for manual validation, but the page explicitly prohibits automated extraction. This is an important architectural lesson: public visibility is not API permission. Use it as a human reference and obtain a documented data product for automation.

Normalize OCC symbols, expirations, strikes, type, and multiplier while retaining the provider's native identifier.

Record the timestamp for the underlying, quote, trade, Greeks, and open interest independently. Do not label a mixed-age response real-time.

Splits, special dividends, adjusted contracts, symbol changes, and non-standard deliverables expose weak normalization quickly.

Store the provider payload and entitlement context before calculating screens or Greeks, so results can be reproduced.

A usable chain also needs synchronized market and analytics fields.

Illiquid contracts can retain old trades while the current market has moved.

Different assumptions can produce different values even from the same quote.

A visible webpage may expressly forbid automated extraction and does not grant redistribution rights.