ChatGPT or Claude for ProBuilder code: why it fails, and the alternative

“How to use ChatGPT for trading” and “ChatGPT vs Claude for trading” are among the most searched questions by traders who code. If your platform is ProRealTime, the honest answer is short: both are excellent at explaining a strategy and both are unreliable at writing the ProBuilder code for it. This tutorial shows why, with real examples, compares the two, and explains what to use instead.

What ChatGPT and Claude are actually good at

Let us be fair first. General AI assistants are genuinely useful to a trader:

• Clarifying an idea. “Explain a mean-reversion strategy on RSI with a trend filter” gets a clear, correct explanation.
• Structuring rules. They turn a vague idea into a list of entry, exit and risk rules you can then implement.
• Explaining concepts. Walk-forward, overfitting, position sizing, Sharpe ratio: good answers, in your language.
• Python, Pine Script, MQL. They have seen enormous amounts of code in these languages and produce usable drafts.

The problem starts when you ask for ProBuilder, ProOrder or ProScreener code.

What a typical ChatGPT ProBuilder answer looks like

Ask ChatGPT for “a ProRealTime strategy that buys when the close crosses above the 20-period SMA and sells when it crosses below, with a 50-point stop” and you get something like this:

// SMA crossover strategy for ProRealTime
sma20 = sma(close, 20)

if crossover(close, sma20) then
    buy 1 contract at market
end

if crossunder(close, sma20) then
    sell at market
end

stoploss = 50
setStopLoss(stoploss)

It reads well. It also fails on the first line. Here is what is wrong:

• sma(close, 20) does not exist. The ProBuilder function is Average[20](close), with the period in square brackets before the series.
• crossover() and crossunder() are Pine Script. ProBuilder uses the operators CROSSES OVER and CROSSES UNDER.
• end is not a keyword. Blocks close with ENDIF.
• setStopLoss() is invented. The instruction is SET STOP pLOSS 50 (in points) or SET STOP LOSS (in price units).
• Nothing prevents order accumulation on repeated signals; a real system needs DEFPARAM CumulateOrders = false.

Five errors in twelve lines, and every one of them is a function or keyword borrowed from another platform. This is the correct version:

DEFPARAM CumulateOrders = false

sma20 = Average[20](close)

IF close CROSSES OVER sma20 THEN
  BUY 1 CONTRACT AT MARKET
ENDIF

IF close CROSSES UNDER sma20 THEN
  SELL AT MARKET
ENDIF

SET STOP pLOSS 50

Why it happens: the problem is structural, not a bad prompt

Users often assume they prompted badly. They did not. Three causes make general assistants weak at ProBuilder, and no prompt fixes them:

1. Too little ProBuilder in the training data

Large language models learn from what is public on the web. Python, Pine Script and MQL are everywhere; ProBuilder is a small language used by one platform, with documentation spread over PDFs and forum threads. When the model has not seen enough of a language, it fills the gaps with the closest thing it knows, which is Pine Script. Hence crossover(), ta.ema and strategy.entry showing up in “ProRealTime” code.

2. No way to verify

A general assistant cannot check whether AverageTrueRange takes its period in [14] or (14), whether a reserved word exists, or which options DEFPARAM accepts. It produces the most probable text, and probable is not the same as correct. It will also apologise and produce a different wrong answer when you paste the error, because it still cannot check.

3. No knowledge of the platform’s rules

Even syntactically correct code can behave wrongly on ProRealTime: orders that accumulate, indicators that repaint because a TIMEFRAME block lacks updateonclose, a strategy that re-enters on every bar, a screener that exceeds the platform’s limits. These rules live in the community’s experience, not in the model.

ChatGPT vs Claude for trading code

Traders regularly ask which one is better. On ProBuilder specifically, the difference is smaller than the difference between either of them and a specialised tool, but here is what we observe:

In short: use either of them to think, neither of them to write ProBuilder you intend to run.

The alternative: an assistant built for ProRealTime

ProRealAI was built by the ProRealCode team, the reference community of ProRealTime users, to solve exactly the three problems above.

• It knows only one platform. ProBuilder, ProOrder and ProScreener, with more than a decade of the community’s indicators, strategies, screeners and forum threads behind every answer.
• It verifies before it answers. Every function, reserved word and DEFPARAM option is checked against the official ProRealTime documentation before a single line of code is displayed. If something does not exist on the platform, it says so instead of inventing it.
• It is wired live to prorealcode.com. The library, snippets and forum are searched in real time. When the community solves a problem, the assistant can use the solution the same day.

The verification steps are visible on screen while it works, so you can see what it looked up. Each code block has a Copy button, the destination named (Indicator, Strategy or Screener), and the exact path to paste it into ProRealTime.

How to use it, in three steps

1. Sign in with your free ProRealCode account at ai.prorealcode.com. You get 150 free credits every 30 days, no card required.
2. Describe the strategy in plain words: market, timeframe, entry, exit, stop. Or paste the code ChatGPT gave you with the error message, and ask for the corrected version.
3. Copy, paste, backtest. Then iterate in the same conversation: “add a trailing stop”, “turn it into a screener”, “why does it never go short?”.

What it does not do

ProRealAI writes, fixes and explains code. It gives no investment advice, no signals, and has no access to live market data. Its syntax is verified; its logic, like any AI’s, must still be reviewed and backtested before real use.

A workflow that uses each tool for what it is good at

1. Think with ChatGPT or Claude. Refine the idea, list the rules, discuss risk management.
2. Code with ProRealAI. Paste the list of rules and ask for the ProOrder system. Fix any error there, not in the general assistant.
3. Test in ProRealTime. Backtest, walk-forward, then paper trade before any live account.
4. Ask the community. Post the result in the ProRealAI group or on the ProRealCode forum for a human review.

Frequently asked questions

Can I paste code from ChatGPT into ProRealAI to fix it?

Yes. Paste the code and ProRealTime’s exact error message. The assistant locates the cause and returns the corrected version. It is one of the most common ways people use it.

Is ProRealAI a subscription?

No. 150 free credits every 30 days, then optional credit packs from €5. Purchased credits never expire. A typical exchange costs about 9 credits. Full details on the ProRealAI guide page.

Which languages?

Interface in English, French, German, Spanish, Italian, Swedish and Dutch, and it answers in the language of your question.

Are my conversations used to train an AI?

No. Conversations are not used to train the provider’s model, and you can delete them at any time.

Where do I ask questions or get support?

In the ProRealAI group on the forum. Support and question topics about the assistant are gathered there: report a wrong answer, share a prompt that worked, ask for a feature, or follow announcements. Joining is free with your ProRealCode account.

Try it

Take the last piece of ProBuilder code a chatbot gave you that would not compile, open ai.prorealcode.com, paste it with the error message, and compare. The first 150 credits are free. Tell us how it went in the ProRealAI group.

Also available in French, German, Spanish, Italian, Swedish and Dutch.