thinkorswim Review 2026: The Most Powerful Free Trading Platform

thinkorswim (commonly abbreviated as TOS) is a professional-grade desktop trading platform that is widely considered the most feature-rich free platform available to retail traders. Originally created by Tom Sosnoff and Scott Sheridan (who later founded tastytrade and tastyworks), thinkorswim was acquired by TD Ameritrade in 2009 for approximately $606 million. Following Charles Schwab's acquisition of TD Ameritrade in 2020 (completed in 2023), thinkorswim is now operated by Charles Schwab.

The fact that thinkorswim is completely free for funded Schwab clients is remarkable. The platform rivals — and in many areas surpasses — software that costs hundreds of dollars per month. Its options analytics are considered the best in the retail space, its ThinkScript programming language enables deep customization, and its OnDemand feature is unlike anything else available.

History: From Startup to Industry Standard

thinkorswim was founded in 1999 by Tom Sosnoff, a former floor trader at the Chicago Board Options Exchange (CBOE), and Scott Sheridan. The platform was designed specifically for options traders — a market segment that was poorly served by existing retail platforms at the time. Sosnoff's floor trading experience informed the platform's design, resulting in tools that reflected how professional options traders actually think about risk and probability.

TD Ameritrade's acquisition in 2009 brought thinkorswim to a massive user base and provided the resources for continued development. Under TD Ameritrade, thinkorswim became the flagship platform and a key competitive differentiator. The Schwab acquisition raised concerns about the platform's future, but Schwab has committed to maintaining and developing thinkorswim, recognizing its importance to active traders.

Options Analytics — Best in Class

thinkorswim was built for options traders, and its options analytics remain the gold standard in retail trading. The Analyze tab is the centerpiece:

• Risk Profile — Visualize the profit/loss profile of any options position at expiration and at any date before expiration. Adjust volatility assumptions to see how changes in implied volatility affect your position.
• Probability Analysis — See the probability of profit, probability of touching, and probability of expiring in-the-money for any options strategy. These probabilities are derived from the options pricing model and reflect real market expectations.
• Greeks Dashboard — Monitor Delta, Gamma, Theta, Vega, and Rho for individual positions and your entire portfolio in real-time. Understand exactly how your portfolio will respond to changes in price, time, and volatility.
• Theoretical Price Calculator — Model hypothetical scenarios by adjusting underlying price, implied volatility, days to expiration, and interest rates to see how your options positions would be affected.
• Spread Hacker — Scan the entire options market for spreads that meet specific criteria (e.g., credit spreads with probability of profit > 70% and return on risk > 15%).

ThinkScript: Custom Programming Language

ThinkScript is thinkorswim's proprietary scripting language that allows traders to create custom indicators, studies, strategies, watchlist columns, and scan criteria. It's more accessible than languages like AFL or C# but more powerful than simple point-and-click builders.

# Volume Spike Detector in ThinkScript
# Highlights bars where volume exceeds 2x the 50-period average

declare lower;

def avgVol = Average(volume, 50);
def volSpike = volume >= 2 * avgVol;

plot Vol = volume;
plot AvgLine = avgVol;

Vol.SetPaintingStrategy(PaintingStrategy.HISTOGRAM);
Vol.AssignValueColor(
    if volSpike then Color.CYAN
    else if close > open then Color.GREEN
    else Color.RED
);

ThinkScript can be used to create custom chart studies, watchlist columns that display custom calculations for every symbol, and scan criteria that filter the entire market based on complex conditions. The language has a large and active community, with thousands of shared scripts available on forums like UseThinkScript.com.

OnDemand: The Market Time Machine

OnDemand is one of thinkorswim's most unique and underappreciated features. It's essentially a "DVR for the stock market" — you can select any historical date and time, and the platform will replay the market exactly as it happened, with real tick-level data flowing into your charts, DOM, and order entry tools.

• Practice Trading Historical Events — Replay the 2020 COVID crash, the 2021 GameStop squeeze, or any other historical event and practice trading it in real-time with paper money.
• Strategy Validation — Test your trading approach against historical market conditions without risking real capital.
• Education — New traders can experience what real market volatility feels like without the financial risk.
• Speed Control — Play back the market at 1x, 2x, 4x, or 8x speed, or pause and step through bar by bar.

Active Trader (DOM & Price Ladder)

The Active Trader module is thinkorswim's price ladder / DOM (Depth of Market) interface, designed for fast execution:

• One-Click Trading — Execute market, limit, and stop orders with a single click directly on the price ladder.
• Auto-Send Orders — Optionally bypass the order confirmation dialog for maximum speed.
• OCO Brackets — Automatically attach stop-loss and take-profit orders to every new position.
• Flatten Button — Close all positions in a symbol with a single click.
• P&L Display — Real-time profit/loss displayed directly on the price ladder.
• Level II Data — Full market depth showing all bid and ask levels.

Charting & Technical Analysis

thinkorswim's charting is comprehensive, with over 400 built-in studies and indicators. The platform supports all standard chart types plus specialized types like Monkey Bars (a simplified Market Profile), Equivolume, and various exotic chart styles. Charts support multiple timeframes, multiple data overlays, and extensive customization through ThinkScript.

One notable charting feature is the ability to display earnings, dividends, and corporate events directly on price charts, which is invaluable for fundamental-aware technical traders. The platform also includes a comprehensive drawing tool set with trendlines, channels, Fibonacci tools, and annotations.

Platform Versions

Commission Structure (Charles Schwab)

Pros and Cons

Who Should Use thinkorswim?

thinkorswim is the obvious choice for US-based options traders. Its Analyze tab, probability tools, and Spread Hacker are unmatched in the free platform space. It's also excellent for active stock and futures traders who want a comprehensive, all-in-one platform without paying monthly software fees.

The platform is also ideal for traders who want to learn and practice. The combination of paper trading, OnDemand historical replay, and extensive educational resources makes thinkorswim one of the best platforms for developing trading skills. However, it's only available to US residents with Schwab accounts, which limits its accessibility internationally.

Final Verdict

thinkorswim is, quite simply, the most powerful free trading platform available. Its options analytics are best-in-class, ThinkScript provides genuine customization capability, OnDemand is a unique and invaluable learning tool, and the Active Trader DOM is fast enough for serious scalping. The fact that all of this is available at zero cost to Schwab clients is extraordinary. If you're a US-based trader, there is no reason not to have a thinkorswim account.