Polygon.io

Polygon.io — US stocks, options and crypto with a developer-grade API; the free tier is end-of-day only

When you are building something and want an API with proper docs, SDKs and a path to real-time — US stocks first, options and crypto beside them — and can live with the free tier's five calls a minute while you prototype.

equitiesoptionscryptofxUnited States

Asset classesequities · options · crypto · fx

Frequencyintraday → monthly

History2000s → today

Limit · costFree: 5 calls/min, end-of-day, 2 years of history · paid from about $30/month

KeyFree key needed — Sign up at polygon.io; the key is instant.

Formats · pull withjson · csv — python, excel

LicencePolygon terms: personal use on the free tier; display and redistribution need a paid plan and, for some data, exchange agreements.

RedistributeNo — link and pull, do not republish

Best for“A well-documented US equities API to build on” · “Option chains and aggregates on a paid plan”

When to use it

Reach for it when…

Not for: Non-US markets (EODHD, Twelve Data), macro (FRED), free-tier real-time (paid only), anything you will redistribute.

How to read it

Units, revisions, traps

Units. Prices in US dollars; timestamps are Unix milliseconds — convert with unit='ms'. Aggregates are adjusted by default (adjusted=true).

Revisions. Adjusted aggregates change with corporate actions.

Five calls a minute on the free tier — add a sleep or the API returns 429.
The previous-close endpoint is the cheapest way to get today's price; aggregates for a range cost one call regardless of length.
Options tickers have their own format (O:AAPL260117C00200000).

Classic mistake: Reading the 't' timestamp as seconds.

How to use it in your own work

Three recipes

Recipe 1 · Daily aggregates for a stock
Recipe 2 · Previous close for a list
Recipe 3 · An option contract's daily bars (paid)

Each recipe: Python · Excel · Sheets, with how to read the result. Python recipes run under pandas; recipe 1 is re-run by the weekly check where the source allows it.

How to use it in your own work

Copy the snippet, change the series id, read the result the way the footer says. Replace YOUR_…_KEY with your own key where one is needed.

Recipe 1Daily aggregates for a stock

import requests, pandas as pd
KEY = "YOUR_POLYGON_KEY"
u = f"https://api.polygon.io/v2/aggs/ticker/AAPL/range/1/day/2026-01-01/2026-09-08?adjusted=true&sort=asc&limit=500&apiKey={KEY}"
df = pd.DataFrame(requests.get(u, timeout=30).json()["results"])
df["date"] = pd.to_datetime(df.t, unit="ms")
print(df.set_index("date")[["o", "h", "l", "c", "v"]].tail())

How to read the resultColumns are single letters (o h l c v); vw is the volume-weighted average price.

Recipe 2Previous close for a list

import requests, time
KEY = "YOUR_POLYGON_KEY"
for t in ["AAPL", "MSFT", "NVDA"]:
    j = requests.get(f"https://api.polygon.io/v2/aggs/ticker/{t}/prev?adjusted=true&apiKey={KEY}", timeout=30).json()
    print(t, j["results"][0]["c"])
    time.sleep(13)   # free tier: 5 calls a minute

How to read the resultYesterday's close, adjusted; for a longer list the free tier takes minutes — plan around it.

Recipe 3An option contract's daily bars (paid)

import requests, pandas as pd
KEY = "YOUR_POLYGON_KEY"
u = f"https://api.polygon.io/v2/aggs/ticker/O:AAPL260117C00200000/range/1/day/2026-01-01/2026-09-08?apiKey={KEY}"
print(requests.get(u, timeout=30).json().get("resultsCount"))

How to read the resultThe ticker encodes underlying, expiry (YYMMDD), C/P and strike × 1000.

Series → question map

The ids we use from Polygon.io, each with the question it answers. The catalog's compare view reads the concept tags behind these rows.

Series	Answers	Region	Concept
aggs · 1/day	Daily OHLC for a US stock	United States	ohlc_daily
aggs · 1/minute	Intraday bars (paid)	United States	intraday
options aggs	Option contract prices (paid)	United States	options
crypto aggs	Crypto bars	global	crypto_spot

Compare with

Same question, different source: Twelve Data, EODHD, SEC EDGAR APIs. The compare view lines up coverage, frequency, history and access side by side and lists what the combination makes possible.

Open compare: Polygon.io · Twelve Data · EODHD →

Questions readers ask

What is free?

End-of-day aggregates, five calls a minute, two years back. Real-time and options need a paid plan.

Is Polygon good for non-US stocks?

No — it is US-centric. Use EODHD or Twelve Data for Asia and Europe.

Do they have a Python library?

Yes, polygon-api-client on PyPI; the raw REST calls above need nothing but requests.

Educational only — we explain, we never advise · snippet licence: public domain · corrections to [email protected], fixed within a day and logged in the changelog.