# QUANTHEON Lab > A no-code stock-strategy backtester framed as an AI quant research desk you direct in plain English: it builds, stress-tests and helps correct your strategy or portfolio, then runs an honest backtest with realistic costs. Among its tools, it proves the edge is real with Walk-Forward, Monte-Carlo and the Deflated Sharpe ratio before you risk a cent. QUANTHEON Lab lets anyone design, backtest and stress-test trading strategies and portfolios without writing code. You describe an idea in plain English (or import a Pine Script / thinkScript / MQL / EasyLanguage strategy), the engine builds an editable visual block graph, and the Overfitting Polygraph fuses out-of-sample Walk-Forward, a 1,000-path Monte-Carlo simulation and a Deflated-Sharpe haircut into a single verdict: trustworthy, fragile or curve-fit. Every backtest carries a reproducibility receipt. Free to start. ## Guides - [What is overfitting in trading strategies (and how to detect it)](https://app.quantheonlab.com/guides/what-is-overfitting): What overfitting is, its warning signs, and the four tests that prove an edge is real. - [How to backtest a trading strategy (no code), step by step](https://app.quantheonlab.com/guides/how-to-backtest-a-trading-strategy): The honest five-step method for backtesting without programming. - [Build and validate a strategy in QUANTHEON Lab: a full walkthrough](https://app.quantheonlab.com/guides/strategy-workbench-walkthrough): End-to-end tour of the Strategy workbench — brief the AI desk, edit the graph, backtest, and get an overfitting verdict. - [Build and backtest a portfolio in QUANTHEON Lab: a full walkthrough](https://app.quantheonlab.com/guides/portfolio-lab-walkthrough): End-to-end tour of the Portfolio Lab — presets, contributions, shared-capital simulation, attribution and weight optimization. - [Independent blend vs a shared-capital book](https://app.quantheonlab.com/guides/shared-capital-portfolio): The difference between blending independent equity curves and running one account where sleeves compete for capital bar by bar — deployment, cash redistribution, per-holding ceilings, and when to use each. - [Backtesting one strategy on many stocks](https://app.quantheonlab.com/guides/multi-asset-backtesting): Why one ticker proves nothing, how the aggregate and the per-asset spread differ, why profit factor is aggregated as a median, and why per-asset parameter tuning is overfitting. - [Walk-forward analysis, explained](https://app.quantheonlab.com/guides/walk-forward-analysis): Rolling in-sample/out-of-sample windows stitched into a 100% out-of-sample equity curve. - [Monte-Carlo simulation for trading strategies](https://app.quantheonlab.com/guides/monte-carlo-simulation-trading): Reshuffling trades to estimate probability of profit, drawdown distribution and risk of ruin. - [The Deflated Sharpe ratio (and PSR), explained](https://app.quantheonlab.com/guides/deflated-sharpe-ratio): Why testing many configurations inflates the best Sharpe, and how deflating for the number of trials fixes it. - [Adaptive position sizing: scale exposure with a signal](https://app.quantheonlab.com/guides/adaptive-position-sizing): Scaling trade size by volatility, VIX or trend strength — and testing that the response curve holds out-of-sample. - [Custom indicators: build once, reuse everywhere](https://app.quantheonlab.com/guides/custom-indicators): Reusable formula indicators, exact (not approximated) import reconstruction, and "Used in" traceability. - [The Strategy Score, explained](https://app.quantheonlab.com/guides/strategy-score): A free 0–100 blend of a strategy's realized metrics for fast triage — and why to pair it with the Overfitting Polygraph. ## Free calculators - [Sharpe ratio calculator](https://app.quantheonlab.com/tools/sharpe-ratio-calculator): Return, risk-free rate and volatility → Sharpe ratio, with a plain-English verdict. - [Max drawdown calculator](https://app.quantheonlab.com/tools/max-drawdown-calculator): Paste an equity curve → maximum peak-to-trough drawdown. - [Position size calculator](https://app.quantheonlab.com/tools/position-size-calculator): Account, risk %, entry and stop → exact share size and cash at risk. - [CAGR calculator](https://app.quantheonlab.com/tools/cagr-calculator): Compound annual growth rate from a start value, end value and years. - [Sortino ratio calculator](https://app.quantheonlab.com/tools/sortino-ratio-calculator): Risk-adjusted return counting only downside volatility. - [Kelly criterion calculator](https://app.quantheonlab.com/tools/kelly-criterion-calculator): Optimal bet size from win probability and payoff ratio, with half-Kelly and expectancy. - [Deflated Sharpe ratio calculator](https://app.quantheonlab.com/tools/deflated-sharpe-calculator): Price the search behind a backtest: observed Sharpe, number of configurations tried and sample length in, probability the edge survives the selection bias out. ## Deep dives - [How QUANTHEON Lab works — the technical whitepaper](https://app.quantheonlab.com/whitepaper): Vendor-neutral internals: typed-AST strategies, a deterministic no-look-ahead kernel, the anti-overfitting stack, and the shared-capital allocation intelligence. - [Turn a Pine Script into an editable, no-code strategy](https://app.quantheonlab.com/pine-script-to-no-code): Paste Pine Script, thinkScript, MQL or EasyLanguage; AI rebuilds an editable visual block graph you can backtest and validate. ## Start - [Open the app](https://app.quantheonlab.com/): Build and stress-test a strategy or portfolio free, no code. - [Learn](https://app.quantheonlab.com/learn): Every guide, calculator and the whitepaper in one place.