Online Strategy Judge: test a Pine Script in your browser
Strategy Arena's online judge is a free web tool that tests a pasted Pine Script strategy out of sample, to catch overfitting: the last 20% of the candles stay sealed while the script is replayed, and the verdict rests on that sealed period. The Lab replay engine, compiled to WebAssembly, runs in your browser: it replays the script on frozen Binance data and returns a verdict, survives, mirage, inconclusive or not enough trades. The script is judged as it is, with no variant search.
- Paste your Pine v5 into the text area, or load the EMA 9/21 example in one click.
- Choose the data: BTCUSDT, in 1 d (full history), 4 h (3 years) or 1 h (1 year).
- The calculation runs in your browser, inside a Web Worker, with a progress bar.
- Read the verdict, the judge's three reasons, the chart, the trade list, then share the card if you want.
To write or edit a Pine, you need TradingView. New accounts only: free account, and $15 off a first subscription through this link. TradingView →
This journal stays in your browser and is never sent to the server. You can erase it at any time. It informs and proves nothing: it does not change the verdict and does not replace the Lab’s trial counter. A script changed even by one space counts as a different script.
The copied text contains your script. Nothing is sent: you paste it yourself into your AI. Research on past data, not advice.
Trades on the sealed period
To search better, test variants and count your trials, use the desktop Lab, free for Windows and Linux.
Real example: why an EMA 9/21 crossover is not conclusive
Here is what the judge answers to this page’s example script, on BTCUSDT daily candles, with 0.10% fees per fill. Computed on 4 November 2026 by the same engine that runs in your browser. Data: Binance, up to 2026-10-16.
Verdict: not conclusive. The script beats holding BTC on the period it never saw (+2.9% against −23.2%), but 35 random markets out of 100 do as well. Chance is enough to explain its lead: we cannot say it has a real edge.
1. The history cut in two
The judge replays the script on the first 80% of the history, then assesses it on the last 20%, from 2024-12-17 to 2026-10-16, which it never saw. On this sealed period it made 16 trades, green when they win and red when they lose.
2. What it earns per year, before and after the cut
On training, +67.2% per year. On the period it never saw, +1.6% per year. This is the typical gap of overfitting: a simple rule looks brilliant on the past used to pick it, much less afterwards.
3. The sealed period, day after day
The script stays almost flat while BTC falls: it avoids part of the drop, which explains its lead over holding.
4. What fees take
Before fees, about +6.2%; after fees, +2.9%. Estimate from the 16 sealed trades.
5. Against chance
The judge replayed the market at random 1,000 times, keeping its shape. 348 times out of 1,000, a strategy with no edge does as well as this script against holding. To rule out chance, it would take 5 times out of 100 at most.
What “holds” would have taken
- ✓ At least 10 trades on the sealed period: 16.
- ✓ Better than holding BTC: +2.9% against −23.2%.
- ✓ Solid on training, trials counted (deflated Sharpe at least 95%): 99.98%.
- ✗ Not explained by chance (5 out of 100 at most): 35 out of 100.
Definitions of the terms
- Sealed period
- The last 20% of the history, kept apart: the script never saw them.
- Overfitting
- A strategy tuned so closely to the past that it learned its noise.
- Holding
- Buying at the start and waiting. Any strategy has to do better.
- Test against chance (SPA)
- The market is replayed at random, keeping its shape; we count how often a strategy with no edge does as well. Hansen’s SPA test, 2005.
- Deflated Sharpe
- The Sharpe ratio corrected for the number of scripts tried. Bailey and López de Prado, 2014.
Research on past data, not advice. Data: Binance, CC BY-NC-SA 4.0 licence.
Which test gives a verdict?
| Tool | Where it runs | Cost | What it answers | Variant search |
|---|---|---|---|---|
| Online judge (this page) | Your browser | Free | A verdict on a sealed period | No, the script as it is |
| Quick Check | The site | Free | Pine compatibility only, no verdict | No |
| Strategy Arena Lab | Your PC, Windows or Linux | Free | A verdict on a sealed period | Yes, every variant is counted |
| Survival Audit | The server | 9.90 EUR, once | Bounded stress tests in a private report | No, the exact code is fixed before payment |
Limits
- One script, as it is: the judge searches no variant.
- Past data: a verdict says nothing about the next period.
- Not advice: research on past data, not an investment recommendation.
- The judge follows the script: orders fill at the close of the signal bar with process_orders_on_close=true, at the next open without it, as on TradingView. The model used is shown with the verdict.
- Real TradingView check on 1 November 2026, BINANCE:BTCUSDT, 1D, 8 scripts covering the four execution models: 2,433 closed trades out of 2,433 with the same dates, 2,418 with the same prices as well (the 15 others in December 2017, up to 65.89 USDT apart, where TradingView shows other prices than our candles). These are measurements on these scripts, not a guarantee for every Pine.
FAQ
Is the online judge free?
Yes. The page, the calculation in your browser and the verdict card are free, with no installation.
How do I know if my Pine strategy is overfitted?
Compare its training result with a period it never saw, then check whether random markets do as well. The judge does both: it seals the last 20% of the candles and runs an SPA test against 1,000 random draws. Its error rate was measured on 3 November 2026 on synthetic markets: 0 false positives on 300 markets with no signal, and 82 detections on 100 markets with a planted signal. Synthetic markets say nothing about real ones.
Is my Pine code sent to Strategy Arena?
No. The calculation runs in your browser; the Pine is sent to the server only if you choose to make it public on a card.
How is it different from the desktop Lab?
The judge tests one script as it is, with no search. The Lab searches variants, counts trials, can be driven over MCP and exports Pine.
Which Pine scripts are accepted?
A Pine v5 script supported by the importer. Otherwise the judge refuses it with the exact reason, function and line, rather than testing an approximate strategy.
Where does the data come from?
From Binance, BTCUSDT: Binance daily candles for 1D, Prisme's archive for 4h and 1h, under the CC BY-NC-SA 4.0 licence. The judge stays free and sells no derived data.
How do I share a verdict?
Any verdict can become a public card with a link, a SHA-256 hash and a preview image; the Pine appears only if you make it public.
Go further: testing a Pine script out of sample, tools compared · what the judge answered to old rules · check a Pine written by an AI
Data: Binance, CC BY-NC-SA 4.0 licence. Research on past data, not advice. manifest