So you want to use AI to build your own forecasting tool in 5 minutes?
The future of finance is not just AI. It's a set of skills that makes you irreplaceable.
While most CFOs wait to adopt AI, I built a forecasting tool in 5 minutes without hiring a single engineer. Here's how CFOs can use AI to build tools.
The whole process took me 5 minutes.
Obviously, it’s a basic forecasting example, but imagine if you keep improving it with better prompts… How useful this can be for your company.
Before diving into how to build your own forecasting tool, it is important to understand where AI is heading and why this matters to CFOs.
Read on.
Coding, Advanced Reasoning and AI agents
3 days ago, Claude released Opus 4 and Claude Sonnet 4.
These models aren’t like ChatGPT, Gemini, or Grok.
These new models are built for coding and building practical applications. For CFOs, this is a big deal. Claude 4 is not a chatbot. It’s your new AI developer, capable of building tools to automate and improve your financial processes.
Imagine AI that builds apps to manage your workflows, from reconciling accounts to generating real-time financial dashboards. As AI continues to change, it’s becoming clear that the future of finance is not chatbots.
The future of finance is autonomous coding engines that can plan, reason, and build real tools from scratch.
ChatGPT, Gemini, and Grok are racing to become your everyday assistant. They remember your preferences, offer helpful answers, and chat in multiple languages.
But Claude isn’t trying to be your buddy. It’s trying to build what you need.
And that’s where the real advantage of AI is.
Finance doesn’t need more conversation.
Finance needs execution.
Finance needs outputs.
Now, let’s build a forecasting tool in 5 minutes with Claude Sonnet 4.
Build a Forecasting Tool in 5 minutes with Claude Sonnet 4
1. Install Cursor from Cursor.com, select a new empty folder as project and select Claud-4-Sonnet as the default model.
COPY-PASTE This Prompt Below
Build an HTML-only forecasting app in the style of the Apple website. Just build the website for now; I will later give detailed instructions on the forecasting functionality.
2. Wait until it’s done. Hit F5 and a browser opens with the basic website.
The website is now ready. Instead of an Apple-style website, you can build a site that matches your company’s website, with your brand colors. How cool that would be!
3. Awesome! You can see that the site is ready. Now let’s add the forecasting functionality.
COPY-PASTE This Prompt Below
Great, the following functionality is required:
The user uploads one CSV (first column = Account, next ≥ 24 columns named YYYY-MM)
shows the rounded numbers straight away in a table and a line chart
lets the user pick an account, choose a forecast horizon N and one of four methods
• Holt-Winters Seasonal (add a 12-month season to the trend)
• Simple Exponential Smoothing (flat)
• Moving Average (window = 3)
• Linear Regression (straight trend)
draws actuals as a solid line and forecasts as a dashed line, then adds exactly F1...FN columns—no duplicates-each time "Generate" is clicked
lets the user download the updated data as CSV (only the chosen account gets forecast numbers; others stay blank in the F* columns)
Here is an example of the file a user might upload:
Account,2023-01,2023-02,2023-03,2023-04,2023-05,2023-06,2023-07,2023-08,2023-09,2023-10,2023-11,2023-12,2024-01,2024-02,2024-03,2024-04,2024-05,2024-06,2024-07,2024-08,2024-09,2024-10,2024-11,2024-12
NET SALES,83018.83453,78064.45087,78792.86085,86199.95112,88219.30534,92095.68374,78117.35145,71103.2855,76517.45446,80752.12312,84370.09757,92197.90091,93350.40953,94669.12111,99638.94747,96385.57236,114022.6586,120512.2271,112512.4863,118171.1254,128143.2836,128409.3919,130851.509,126268.8278
STAFF EXPENSES,-1197.07757,-1476.86328,-2525.11485,-2290.33005,-814.76191,-432.95914,-89.02685,-29.82346,-23.48863,-54.39942,-61.21488,-553.99858,0,-72.71829,0,23.88683,82.05126,-32.98887,-369.30574,206.45867,-443.5515,-654.07297,-11.41674,-10.41683
MARKETING EXPENSES,-949.48799,-911.18553,-985.23656,-1099.55655,-2798.91928,-2337.24818,-2575.76083,-3333.96627,-3705.50189,-3060.4956,-3773.25704,-2277.59273,-3067.10807,-3115.65319,-3624.35014,-2932.16893,-8606.85116,-8432.49666,-1866.60795,-1261.1363,-1311.07495,-3154.12051,-3831.6338,-1603.55293
RENT & UTILITIES,-8205.8482,-7831.34176,-7840.26245,-7833.18978,-8087.726,-8000.91457,-8515.22421,-5923.28348,-8256.78,-7809.26733,-7895.63015,-4789.64968,-5294.50164,-5111.66113,-5440.33892,-5625.71644,-5980.86703,-5316.62091,-5732.515,-5562.01554,-6689.3927,-6542.91565,-6418.0598,-6165.71286
That’s it! Your forecasting tool is ready.
Upload CSV: Download here
It's a basic example, but it shows what's now possible. Imagine taking that simple starting point and refining it with additional prompts until it's fully customized to your needs.
You don't have to wait for IT or hire engineers. You only need to clearly explain what you want. AI handles the rest.
So if I can build a usable forecasting tool in 5 minutes, imagine what your team could do by investing an hour. Or a day.
The power is here.
You don’t have to wait for anybody’s permission to tap into it.
You can also use ChatGPT 4.1 to build a forecasting app without risking your sensitive data.
CFOs can build a forecasting app in 5 minutes with ChatGPT 4.1
You needed a new forecasting tool. Or a dashboard to monitor costs. Or just a tool that would automate those same manual reports you run every month. Something to make your life easier. Something that would give your team time to focus on strategic work instead of stitching together numbers.
OpenAI Acquired an AI-first Device Company For $6.4 Billion
Soon, we won’t be the ones doing the clicking, swiping, and navigating. Our AI agents will. That means we’ll be less present on the internet and more focused on what we want from it.
And when the doing disappears, the devices change too. Do we still need to stare at screens? Or will we just speak to our agent and let it act?
OpenAI acquired an AI-first device company, Jony Ive’s ‘io’ to build AI hardware.
Jony Ive, the legendary designer behind the iPhone and Apple’s most iconic products.
So I believe the new AI-enabled devices will entirely change how we live, scroll, communicate, and make decisions.
And CFOs, your workflows aren’t exempt.
The finance stack will be reimagined around agents and AI-enabled devices.
The Bottom Line
A CFO using AI won’t take your job.
But a CFO who combines AI with human judgment and strategic thinking will win.
AI doesn’t remove the need for good decisions. It multiplies the impact of them. The best-performing models still need guidance, calibration, and a clear sense of what good looks like.
This is where leadership matters most.
When AI floods you with options, your edge is in knowing which one to choose and why. It’s not about replacing talent with tech. It’s about using AI to expand the reach and relevance of your knowledge.
So yes, adopt AI. But don’t stop there.
Train your judgment. Zoom out. Learn what makes a prompt powerful, how to evaluate AI outputs, and where automation adds real value.
Because in the AI-powered future, the CFO who wins won’t just be using AI.
They’ll be building.
What took hours now takes minutes.
The bar is rising. The rules are changing.
So how do we really stay ahead?
We must focus on what makes us irreplaceable.
Invest in relationships, leadership, and strategic depth. It means becoming the kind of operator AI tools can support, but never replace.
AI might be able to generate a dozen board slides. But only you can decide what story needs to be told.
And that’s exactly why I created this newsletter and private CFO community on Substack.
Because AI is only getting stronger, so is the need for clear thinkers, strong leaders, and deeply human decision-makers.
And that’s all for today.
See you on Thursday!
P.S. Yvonne McGill is the first female CFO at Dell
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I’m Wouter Born. A CFOTech investor, advisor, and founder of finstory.ai
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