Where to get free options chain data

For a full options chain at no cost, Yahoo Finance reached through the yfinance Python package is the practical answer, and it is what most tutorials mean when they say free. That is a useful fact and an incomplete one. Whether it is the right source depends on which chart you are trying to draw, and the comparison tables that rank options data vendors by price and endpoint count never ask that question.

So start from the chart. Four requirements decide which sources can serve you. A source that fails any one of them is not cheap for that job, it is unusable for it.

Requirement one: implied volatility and the Greeks

A volatility smile, a term structure and a volatility surface are all plots of implied volatility. If your feed returns only bid, ask, last, volume and open interest, you do not have those charts. You have the inputs from which to compute them, which means numerically inverting Black-Scholes for equity options, or Black-76 for options on futures, once per contract, and sourcing a risk-free rate and a dividend yield separately to do it. That is entirely doable and it is a real piece of work.

Feeds differ here more than anywhere else. Some publish IV and a full Greek set per contract, some publish neither, and among commercial vendors the IV and Greeks fields are frequently the thing that separates the free tier from the paid one. Check the field list before you check the price.

Requirement two: history of chains, not today's snapshot

This is the requirement that catches people out, because free sources are overwhelmingly snapshot sources. yfinance hands you the chain as it stands now. That is enough for a smile, a surface, or an open interest profile, all of which are pictures of a single moment. It is not enough for anything with time on the x-axis.

The arithmetic is worth doing once, and these are round illustrative numbers rather than a specific ticker. Say a liquid single name lists ten expirations with forty strikes each, calls and puts: roughly eight hundred contracts, for one day. A volatility surface needs that one day. An IV rank chart needs a year of daily observations, so around two hundred and fifty of those days. If your source only ever returns today, the only way to get them is to capture the snapshot yourself every session for a year before the chart can be drawn at all. Historical chain data is the most expensive thing in this market, and that is why.

The practical consequence is a decision on day one: are you buying history, or accumulating it. Both are legitimate. Discovering that you never made the choice, eleven months in, is not.

Requirement three: the whole chain, not the top of book

Some feeds return only near-the-money strikes, or a truncated set per expiration. For a payoff diagram that is fine. For a surface it is not, because the wings are where the shape lives, and a chain truncated by volume systematically removes the deep out-of-the-money contracts that give the smile its smile. If a source does not document how many strikes and expirations it returns, pull one chain and count them.

Requirement four: permission to publish what you charted

This one never appears in the comparison tables, and it is the one that decides whether your chart can go on a public page. Reading data for your own analysis and republishing something derived from it are different acts under most market data licences. Redistribution is commonly restricted on free and low tiers even where the data itself flows freely, and exchange-sourced options data carries its own conditions on top.

Nobody is going to stop you plotting a chain in a notebook. A chart on a public site, in a client report, or in a newsletter is a different question, and the answer is in the terms you accepted rather than in anyone's blog post. Read them before you build the page.

What the free sources actually are

Yahoo Finance, through yfinance, is the de facto free chain, and it is worth being clear-eyed about what that is. Yahoo retired its official public API years ago; the library works by talking to endpoints that were never published as a contract. It is free, widely used, and genuinely good enough for learning, prototyping and personal analysis. It also carries no service guarantee and breaks when Yahoo changes something, which has happened more than once. Do not put it behind anything that has to stay up.

Cboe publishes delayed quote tables on its own site. That is a legitimate free look at real exchange data, and it is built for a human reading a page rather than for programmatic collection, which makes it correspondingly awkward to treat as a feed.

Then there are commercial vendors with free tiers, among them Alpha Vantage, Polygon, Databento, EODHD and Market Data. These are the honest middle: real documentation, real support, real terms, and a free tier shaped to show you what you would be buying. Two things decide whether that tier is useful to you rather than just present, and they are the request limits and whether IV and Greeks are included in it.

This post quotes none of their current numbers, deliberately. Request caps, history depth and which fields sit behind the paywall change more often than the articles describing them get updated, this one included. Open the vendor's own pricing page. If the answer matters, pull a single chain on a free key and look at what comes back, because one request settles what an afternoon of reading comparisons will not.

Once you have the data

Every options chart in this series assumes this step is solved. Open interest by strike, implied volatility term structure, the equity put/call ratio and IV rank and IV percentile all start from a chain you already hold, and the last of those is the one that needs a year of them.

Quadesto reads an options chain in whatever shape you have it, whether that is a CSV export, a JSON payload or a connected source, with prebuilt connectors for Alpha Vantage and Databento among others. It infers that the data is a chain rather than a price series and proposes the chart that fits it.

[QUADESTO-EMBED: side-by-side field comparison of one options chain as returned by a snapshot feed vs a full vendor feed, highlighting which columns each supplies]

Bring an options chain in any format and see what it will chart.