API Reference

TestMax exposes two REST APIs that give you full programmatic control over backtesting, order execution, and strategy management. Whether you are building a Python trading bot, integrating with an external tool, or automating your workflow, these APIs cover everything you need.

The two APIs

TestMax has two distinct APIs, each serving a different purpose:

TopStep Simulator API

Base path: https://api.test-max.com/api/topstep-sim/

The TopStep Simulator API emulates the real TopStep ProjectX Gateway API. It exposes the same endpoints, request formats, and response shapes so that strategies you build for TestMax can be ported to live trading with minimal changes.

This is the API you use when writing Python strategies in the Algo Playground or when building standalone trading bots.

Authentication: Bearer token obtained via Auth/loginKey (requires an API key generated in Settings).

Covers: Authentication, accounts, contracts, order placement, positions, trades, historical bars, and replay control.

Playground API

Base path: https://api.test-max.com/api/playground/

The Playground API manages the Algo Playground experience — running backtests, managing saved strategies, browsing templates, and viewing run history.

Authentication: Cookie-based JWT (same session as the web app). No additional API key required.

Covers: Strategy templates, backtest execution, speed control, strategy CRUD, and run history.

Base URL

All API requests are made to:

https://api.test-max.com

The full URL for any endpoint is the base URL plus the API path. For example:

https://api.test-max.com/api/topstep-sim/Auth/loginKey
https://api.test-max.com/api/playground/templates

Standard response format

Every API response follows a consistent JSON structure:

{
  "success": true,
  "errorCode": 0,
  "errorMessage": null,
  ...data
}

Field	Type	Description
success	boolean	true if the request succeeded, false if there was an error
errorCode	number	0 for success, non-zero for errors
errorMessage	string or null	Human-readable error description, or null on success

Additional data fields are included alongside these three fields depending on the endpoint. For example, Account/search returns an accounts array at the top level of the response object.

Caution

Always check success before processing response data. Even HTTP 200 responses may contain "success": false with an error message if the request was semantically invalid (e.g., placing an order with insufficient margin).

Authentication overview

TopStep Simulator API

The TopStep Simulator API uses Bearer token authentication.

1. Generate an API key in the TestMax web app under Settings > API Keys
2. Send a POST request to Auth/loginKey with your email and API key
3. Receive a token in the response
4. Include the token in all subsequent requests via the Authorization header

Authorization: Bearer <your-token>

Tokens can be refreshed with Auth/validate and invalidated with Auth/logout.

Playground API

The Playground API uses cookie-based JWT authentication — the same session cookie set when you log into the TestMax web app. No additional API key is needed.

If you are calling the Playground API from a script outside the browser, you will need to include the session cookie in your requests. In practice, most users interact with the Playground API through the web UI, and the cookie is handled automatically.

See the Authentication page for the complete auth flow with code examples.

Rate limits

TestMax enforces the following limits to ensure fair usage:

Limit	Value
Max concurrent backtests per user	1
Backtest execution timeout	10 minutes
Max strategy script size	200 KB
Playground speed range	1x to 50x

There are no per-minute rate limits on individual API calls during a backtest session. The simulator is designed for rapid-fire order placement and bar stepping within a single session.

Getting started

The fastest way to start using the API is through the Algo Playground, where authentication and session setup are handled automatically. If you want to build a standalone bot or integrate directly:

1. Create an account at testmax.io
2. Generate an API key in Settings > API Keys
3. Authenticate via POST Auth/loginKey
4. Search for accounts via POST Account/search
5. Find your contract via POST Contract/search
6. Start a replay session via POST Replay/start
7. Step through bars and place orders using the Order and Replay endpoints
8. End the session via POST Replay/end to get final results

Tip

If you are using the Algo Playground, you do not need to call any of these endpoints manually. The Playground builds a Python script that handles the full lifecycle for you. See the Python API Reference for the higher-level functions available inside strategies.

API reference sections

TopStep Simulator API Full reference for the TopStep-compatible trading API

Authentication API key generation, login, token management

Accounts Search and manage trading accounts

Contracts Search for instruments and contracts

Orders Place, search, modify, and cancel orders

Positions Query and close open positions

Trades Query trade and fill history

Replay Control Start, step, play, pause, and end backtest sessions

History & Bars Retrieve historical OHLCV bar data

Playground API Run backtests, manage strategies, browse templates

Enums & Types All enum values, type mappings, and contract ID format