Best brokers for third-party trading integrations in 2026

The broker you pick decides more than your commissions. It decides which tools you can plug in, whether you can test before risking money, and how much friction stands between a signal and a fill. If you use any outside platform for charting, automation or analysis, the broker's API matters as much as its app.

Here's what to look for, followed by how six brokers with strong third-party support compare.

What makes a broker good for third-party integrations

• OAuth sign-in. You authorize a tool through the broker's own login page instead of pasting API keys into someone else's app. It's safer, and you can revoke access from your broker at any time.
• Paper trading. A simulated environment lets you prove a setup works before real money is involved. Not every API offers one.
• Asset coverage. Stocks and ETFs are standard. Options, index options and crypto vary by broker.
• Multi-leg options. If you trade spreads, the API needs to send them as a single order, not leg by leg.
• Order types. Bracket, OCO and trailing orders make exit management cleaner.
• Cost and limits. Look at per-contract options fees, any API surcharges, and rate limits that could throttle a busy strategy.

How the brokers compare

Public

Public's API is open to all members with no approval step. It covers stocks, ETFs, options including multi-leg strategies, index options and crypto, with real-time quotes included. US-listed stocks and options are commission-free during regular hours, and Public pays rebates on stock and ETF option contracts for enrolled users. The trade-off is that Public's API has no paper trading environment, so test your logic somewhere else first.

Best for: options traders who want low per-contract costs and index options in one account.

Alpaca

Alpaca was built API-first. It supports OAuth for third-party apps and has one of the best paper trading environments available, with its own endpoints and credentials that mirror live trading closely. It covers stocks, ETFs, options and crypto, and self-directed trading of US-listed securities through the API is commission-free.

Best for: anyone who wants to paper trade a new strategy before going live.

Tradier

Tradier is a REST-native broker that authenticates third-party apps through OAuth 2.0. It handles equities and complex multi-leg options, plus advanced order types including OTO, OCO and OTOCO. Equity trades are commission-free and options run up to $0.35 per contract, with subscription plans for higher-volume traders. Tradier also integrates with a long list of third-party platforms.

Best for: options traders who need advanced order types and broad third-party support.

tastytrade

tastytrade is options-focused and offers a public Open API with OAuth for partner integrations and a sandbox environment for testing. API access comes with a brokerage account at no extra charge, and trades follow tastytrade's standard commission schedule.

Best for: active options traders already in the tastytrade ecosystem.

Charles Schwab

Schwab's Trader API uses OAuth and supports stocks, ETFs and options. It's a separate developer product from thinkorswim, and third-party platforms connect through a commercial tier with its own approval process. The upside is that you can keep your existing Schwab account and still use outside tools.

Best for: traders who don't want to move assets away from a large full-service broker.

Moomoo

Moomoo's OpenAPI covers real-time quotes and trading for US stocks and options, with both live and paper trading and no extra charge for API use. Futures aren't offered to US customers.

Best for: traders who want a research-heavy app plus paper trading through the API.

How to choose

• If you trade options heavily, start with Public, Tradier or tastytrade and compare per-contract costs at your volume.
• If you want to test before going live, pick a broker with API paper trading, such as Alpaca or Moomoo.
• If you already have an account you're happy with, check whether your tools support it before you open a new one.

How RelayDesk connects to your broker

RelayDesk connects to every supported broker through OAuth, so you never create or paste an API key. Your money stays in your own brokerage account, and you can revoke access from your broker whenever you want. Public, Alpaca and Tradier are our premier partners, and we also connect with tastytrade, Moomoo and Charles Schwab. More brokers are being added. See the full list on our integrations page and what's next on the roadmap.

RelayDesk is a trading automation platform. We are not a broker-dealer or investment advisor and do not provide investment advice. Trading involves substantial risk of loss. Past performance is not indicative of future results. Broker features and fees reflect public sources as of October 2026 and may change; confirm details with each broker before opening an account. View full disclaimer