Documentation
Zero Days To Expiration SPX Options Trading
0DTESPX.com is a simulated trading platform for zero-days-to-expiration SPX options. Replay any past session or trade today's market in real time, track positions and greeks, and build and backtest strategies. These guides cover every feature, plus the public API.
Getting started
Core concepts
A primer on zero-days-to-expiration SPX index options.
How a trading day is recreated, with a clock you control.
Reading bids, asks, and live delta, gamma, theta, vega and IV.
Market, limit, stop, and multi-leg orders and how they fill.
Tracking direction, cost basis, and realized vs unrealized P&L.
FINRA maintenance-margin rules for shorts, spreads, and condors.
The brokerage fee schedule applied to every order.
What happens to open options at the 4:00 PM ET close.
Trading & research
Paper trade today's session against the real-time tick stream.
Scrub through any past trading day at your own pace.
Define a 0DTE strategy with a structured form.
Describe a strategy in plain English and let the AI author it.
Every saved strategy owns shared backtest results over the recorded history.
Live and historical SPX/VIX data, option chains, and overlays.
API reference
Base URL, auth, access levels, and conventions.
An end-to-end paper-trading tutorial with copy-pasteable curl examples.
The market-data credit budget and per-endpoint costs.
Create simulations, advance the clock, and read financials.
Place, preview, and cancel orders, including multi-leg.
Read computed positions with Greeks and the transaction log.
Sessions, strikes, history, and option-chain snapshots.
Trade today's session: orders, positions, idempotency.
Preview, save, and read content-addressed strategies and their shared backtest results.
Real-time market data and per-simulation event channels.