API trading platforms are an essential building block for modern investors and developers. Whether you want to automate a strategy, build an investing product or backtest systematically, the broker’s API decides what you can actually do.
In this article, we review the leading API brokers by features, reliability, SDK and language support, market coverage and developer experience. Everything here was checked in September 2026.
Best API brokers for 2026
- Alpaca: commission-free broker built API-first. Best for algorithmic trading and developer-led products.
- Interactive Brokers: the most comprehensive API in the industry. Best for non-US investors, multi-asset strategies and institutional-grade infrastructure.
- Tradier: cloud-based API brokerage focused on equities and options. Best for developers building US-focused trading apps.
- Saxo: OpenAPI with broad multi-asset coverage. Best for European developers who want global markets from an EU-regulated bank.
What is a broker API?
An Application Programming Interface (API) is a set of protocols and tools that lets your code talk directly to a broker’s platform. It connects your front end (a trading bot, a portfolio dashboard, a fintech app) to the broker’s execution and data systems, so you can place orders, stream real-time prices, manage positions and pull historical data programmatically.
Before choosing one, check five things:
- Market and asset coverage: can you reach the exchanges and instruments your strategy needs, or only US equities?
- Latency and rate limits: how many requests per minute you get, and whether streaming is available through WebSocket or a similar protocol.
- Sandbox environment: a paper trading endpoint that mirrors production is what lets you test order logic without risking money.
- SDKs and documentation: official libraries in your language save weeks compared with community-maintained wrappers.
- Total cost: the API itself is usually free, but market data subscriptions, commissions and the infrastructure you run the bot on are not.
Best API brokers compared
| Broker | Commission | Instruments | Availability |
| Alpaca | $0 on US stocks, ETFs and options; crypto priced through the spread | US stocks, ETFs, options, crypto | 30+ countries, including the US, most of the EU, the UK, Australia, Singapore and Japan |
| Interactive Brokers | Tiered or fixed pricing from $0.005 per share; options from $0.15 to $0.65 per contract; $0 on US stocks for IBKR Lite (US residents) | Stocks, ETFs, options, futures, forex, bonds, funds and crypto | Worldwide, 160+ markets |
| Tradier | $0 on equities; options from $0.35 per contract, or a flat monthly subscription | US stocks, ETFs, options | US clients, with limited international access through partners |
| Saxo | From 0.08% on US stocks (min. $1); tiered by account level | Stocks, ETFs, options, futures, forex, bonds and funds | Most of Europe, Asia and the Middle East, not US retail |
Fees and coverage checked in September 2026. Availability and pricing change, so confirm with each broker before building on its API.
1. Alpaca
Alpaca was built API-first, which shows in the developer experience: there is no desktop platform to install and no gateway process to keep alive, just REST endpoints and WebSocket streams.
You can paper trade in a full sandbox before deploying capital, which is the right way to test strategy logic, order routing and error handling. The sandbox mirrors the production API, so moving over is a change of endpoint and key rather than a rewrite.
WebSocket streaming covers real-time market data and account updates, and works from any language with WebSocket support. The standard rate limit is 200 requests a minute, with higher limits on paid data plans.
Alpaca maintains SDKs in Python, JavaScript, Go and C#, with community libraries elsewhere. Its Broker API also powers investing features inside other companies’ apps, which is a good signal of how production-ready it is. Documentation is at docs.alpaca.markets.
2. Interactive Brokers
Interactive Brokers offers four APIs: the TWS API (the classic one), the Client Portal Web API, the IBKR Web API and FIX CTCI for institutional clients. The TWS API remains the most used by individual developers.
It supports Python, Java, C++, C#, .NET and VB natively, with active community libraries elsewhere. Through it you can place and manage orders, read positions and trades, stream real-time data, pull historical data and news, and retrieve full account data, across 160+ markets and every asset class IBKR offers, which no other broker on this list matches.
One practical caveat: the TWS API requires a running instance of Trader Workstation or the IB Gateway to connect through, so your bot depends on a desktop process staying alive and re-authenticating. The newer Web API removes that dependency and is worth looking at for server-side applications.
The API is free, beyond standard market data subscriptions. Documentation is at interactivebrokers.com.
3. Tradier
Tradier’s API uses OAuth 2.0, which makes it straightforward to integrate into an application without handling raw credentials. The API is RESTful, with WebSocket support for streaming market data and account updates.
Errors come back as a clean JSON payload naming the field or condition that failed, which makes debugging automated strategies much less painful than parsing generic error codes.
There are separate sandbox and production endpoints, so you can test against simulated data before going live. Official SDKs and community libraries cover the main languages.
Tradier’s strength is options: alongside per-contract pricing it offers flat monthly subscription plans that can work out cheaper for high-volume options traders. Its limitation is scope: US equities and options only, and accounts are essentially for US clients, with limited international access through partners. Documentation is at documentation.tradier.com.
4. Saxo
62% of retail CFD accounts lose money.
Saxo’s OpenAPI is the strongest option on this list for developers outside the US who want more than equities. It is a REST API with streaming support, authenticated through OAuth 2.0, and it exposes the same multi-asset universe Saxo offers through its own platforms: stocks, ETFs, options, futures, forex, bonds and funds across global exchanges.
Saxo provides a free developer portal with a simulation environment, so you can build and test against simulated accounts before applying for live access. There is no charge for the API itself, and Saxo publishes a .NET SDK alongside community libraries in Python and other languages.
Two things to weigh: Saxo’s commissions are higher than Alpaca’s or IBKR’s, so it suits strategies where market access and instrument breadth matter more than cost per trade, and live API access requires a funded account and an application. Saxo is regulated in Denmark and supervised across its European entities, and since 2026 it is majority-owned by the Swiss private bank J. Safra Sarasin.
Which API broker should you choose?
- You’re learning, or building a US equities bot in Python: Alpaca. The cleanest developer experience, a real sandbox and no desktop dependency.
- You need global markets or multiple asset classes: Interactive Brokers. Nothing else comes close on coverage, and the cost per trade is low.
- You trade options heavily in the US: Tradier. The subscription plans can make high-volume options trading much cheaper.
- You’re in Europe and want breadth from a regulated bank: Saxo OpenAPI.
Whatever you choose, budget for what sits around the API: market data subscriptions, a server or virtual machine that stays up, monitoring and a way to kill the strategy quickly when something goes wrong. Those costs, and the time spent on them, usually exceed the commissions.
To sum up, here are our picks:
FAQs
How do I choose the best broker API?
There’s no single best one. Match the API to the strategy: an intraday strategy needs low latency, generous rate limits and reliable streaming, while a long-term rebalancing bot mostly needs stable authentication and good historical data. Check the asset coverage first, since that rules out most options quickly, then compare documentation quality and whether an official SDK exists in your language.
What can you build with a broker API besides a trading bot?
Portfolio analytics and reporting tools, charting applications, tax and performance tracking, risk dashboards, and investing features inside another product. Several fintech apps are built on broker APIs rather than their own brokerage infrastructure, using what is usually called a Broker API or embedded investing API.
What are the advantages and disadvantages of API trading?
Advantages:
- Faster execution: orders are placed in milliseconds, so you can act on short-lived moves.
- Discipline: position size, entry and stop loss are coded in advance, which removes the emotional decisions that hurt most discretionary traders.
- Scale: one script can monitor hundreds of instruments at once.
Disadvantages:
- You need to code: at minimum enough to read API documentation and handle errors properly.
- Setup costs: market data subscriptions, hosting and monitoring add up before the strategy makes anything.
- New failure modes: a disconnection, an expired token or an unhandled error can leave a position open with no supervision, which is why kill switches and alerts matter.
Does Webull have an API?
Yes. Webull now offers an official OpenAPI for the US market, covering trading, market data, a broker API and OAuth account access, across stocks, options, futures, crypto and event contracts, with Python and Java SDKs. Eligible clients apply for access through Webull, and market data subscriptions are bought separately.
Does Trading 212 have an API?
Yes. Trading 212 publishes a public API with documentation at docs.trading212.com, which gives access to account and portfolio data and to order placement. Coverage is narrower than the brokers in this article, so check the current documentation for what is supported before building on it.
Does DEGIRO have an API?
No. DEGIRO does not offer an official API. Unofficial wrappers exist, but they rely on undocumented endpoints, can break without notice and may breach the broker’s terms.
Does Plus500 have an API?
No, Plus500 does not offer an API.
