Replace a $10K-a-Year SaaS Tool in an Afternoon — With Claude

The twelve lines of math you're renting

Look at your software bill and there's a good chance you'll find one of these: a tool whose entire job is simple math on your own data. It takes an export, applies a few rules, and shows you a list. A reorder tracker. A quote calculator. A commission sheet. For that, the vendor charges four or five figures a year — and every year the renewal email comes with a price bump and a list of "new features" nobody asked for.

Here's the uncomfortable part: the actual logic inside a tool like that is often about twelve lines of math. For a reorder tracker: current stock, average weekly usage, lead time, safety buffer. Done.

Tools like that can now be rebuilt in an afternoon with Claude. Not a prototype — a working app you paste your export into and get a clean, sorted answer out of, running on a $20/month subscription you may already have.

This guide walks you through doing it with one of your own tools. You don't need to know how to code. You need to know your own workflow, and you need to be able to copy and paste. By the end, you'll have a working app open in your browser.

Step 1: Pick the right target

Not every SaaS tool is worth replacing. Most aren't. Pick wrong and you'll waste your afternoon. Here's the filter. (If you haven't yet worked out which of your tools are even candidates, run the 30-minute SaaS self-audit first.)

A good target has three traits:

1. It does one narrow job. A reorder tracker. A quote calculator. A commission calculator. A simple job board for your shop. If you can describe what it does in one sentence, it's a candidate.
2. It runs on your data. You feed it a spreadsheet or type numbers in, it gives you an answer back. No connections to other companies' systems.
3. You're paying real money for it. $3K–$15K a year for one narrow job is the sweet spot. That's where the math gets obvious fast.

Now the honest paragraph about what NOT to attempt. Don't rebuild payroll. Don't rebuild accounting. Don't touch anything regulated — HR compliance, tax filing, anything that talks to a bank, anything where a bug means a fine or a lawsuit. And don't try to replace tools whose value is the network, not the software: your CRM full of years of history, a marketplace where your customers already are, an industry platform everyone in your trade uses. Those tools earn their fee. The target is the narrow, overpriced utility that does simple math on your data and charges you like it's doing surgery.

The rest of this guide uses one running example: a reorder-point tracker. You paste in an inventory export, it tells you what to order and how much. Swap in your own tool as you go — the steps are identical.

Step 2: Write the one-sentence job description

Before you touch Claude, write one sentence:

"This tool takes ______ and gives me ______ so I can ______."

For the reorder-tracker example:

"This tool takes my weekly inventory export and gives me a ranked list of parts below their reorder point, with suggested order quantities, so I can place orders Monday morning without hunting through 2,000 rows."

If you can't write that sentence, you haven't picked a narrow enough target. Go back to Step 1. This sentence is the spine of everything that follows.

Step 3: The build conversation

Go to claude.ai and sign in. The free plan can do this, but the paid plan ($20/month) gives you longer conversations and a better model, and for a build session you'll want it. Do this on the paid plan.

Start a new chat. Now here's the trick most people miss: don't ask Claude to build the tool. Ask Claude to interview you first. The tool it builds is only as good as the workflow you describe, and you'll describe it better answering questions than writing an essay.

Copy and paste this entire prompt. Fill in the two blanks at the top first.

I run a business and I want to replace a paid software tool with a
simple custom app that you'll build as an artifact.

The tool's job, in one sentence: [PASTE YOUR ONE-SENTENCE JOB
DESCRIPTION HERE]

The data it works with: [DESCRIBE YOUR DATA — e.g., "a weekly
inventory export from my POS with columns for part number,
description, quantity on hand, average weekly sales, and vendor"]

Before you build anything, interview me. Ask me questions ONE AT A
TIME about:
- exactly what the current tool shows me and what I actually use
- what the input data looks like (I can paste a sample)
- what calculations or rules it applies
- what a "good output" looks like on a normal day
- edge cases: what should happen with missing data, zeros, or
  weird values
- who uses it and how often

Ask at least 6 questions before building. Don't assume anything —
if my answer is vague, push back and ask for a real example.

When you have enough, build a single-page web app as an artifact:
- I paste my data in (copied straight from a spreadsheet, so handle
  tab-separated values)
- it runs the rules we discussed
- it shows me a clean, sorted output I can read in 30 seconds
- include a button to copy the results so I can paste them into an
  email

Keep the design plain and readable. Big text, no clutter. Assume I
am not technical: after you build it, tell me in plain English how
to use it and what its limits are.

Claude will start asking questions. Answer them like you're training a new hire. Paste a real sample of your data when it asks — grab 20 rows from your actual export, copy them from the spreadsheet, paste them into the chat. Real data beats descriptions every time.

Expect the interview to surface things you'd never have thought to write down: vendor minimum order quantities, the two vendors with 3-week lead times instead of 1, discontinued parts that should be skipped entirely. Rules like those live in your head and nowhere else — the interview is how they get into the app.

After the interview, Claude builds the artifact. It shows up as a panel on the right side of your screen — a real, clickable app. Paste your data into it and hit the button.

Step 4: Test with real data, then iterate

The first version will be 80% right. That's normal. Software vendors spend months on the last 20%; you'll spend twenty minutes, because you fix it by talking.

Paste in your full, real export — not the sample — and look for what's wrong. Then tell Claude in plain English. Here are three iteration prompts to steal:

The output looks right, but sort it by dollar value at risk (quantity
needed × unit cost) instead of alphabetically, so the expensive
stuff is at the top.

Some rows in my export have blank "average weekly sales" values and
the app is treating them as needing zero. Instead, flag those rows
in a separate "needs review" list at the bottom.

Add a summary line at the top: total number of parts to reorder and
total estimated order cost. And make the copy button copy it in a
format that pastes cleanly into an email to my vendor.

Each time, Claude updates the artifact in seconds. Keep going until it does the job as well as the tool you're paying for. For a narrow tool, that usually takes three to eight rounds. That's the afternoon.

One practical tip: when you're happy with it, ask Claude to "publish" the artifact — claude.ai lets you save and share artifacts with a link, so you can open your app any time without rebuilding it.

Step 5: Know the limits — and the step up

Here's the honest caveat, and it matters: artifacts don't store data between sessions. Your app doesn't have a database. Every time you use it, you paste your data in fresh. For a weekly reorder run, that's fine — pasting an export takes ten seconds. But if you need the tool to remember things — order history, multiple users, data building up over months — an artifact isn't enough. You need a real app with real storage.

That's the step up, and it's smaller than you think. Claude Code is Anthropic's tool for building actual software, and the same interview-then-build conversation works there — it just produces a real application with a database, user logins, and a URL your team can bookmark. It's more involved than an afternoon, and if you're not up for it yourself, it's a small project for any competent builder. The artifact you built isn't wasted either way: it's a working specification. Hand it to a builder and say "make this, but with saved data" and you've skipped the most expensive part of any software project — figuring out what you actually want.

Step 6: The math

Run your own numbers. Here's the shape of it, using a $10K/year tool as the example:

• The SaaS tool: $10,000/year, every year, forever. Five years: $50,000. Plus the renewal-season price bumps.
• The artifact version: one afternoon plus a $20/month subscription you probably already have. Call it $240/year, and the subscription does a hundred other things.
• The real-app version (built for you): typically a few thousand dollars, one time. It pays for itself against a $10K/year tool in months, and then it's yours. No renewal email. No price bump. No features you didn't ask for.

The catch, stated plainly: you own the maintenance now. If your export format changes, you update the app (usually one more conversation with Claude). For a narrow tool on your own data, that trade is heavily in your favor. For complex, regulated, or networked tools, it isn't — which is why Step 1 is the step that matters most.

The tools worth building this way aren't fancy. They're narrow, they fit your workflow exactly, and they're yours.

Tool names, plans and prices in this guide were checked in August 2026. AI products change fast — verify anything before you buy it.

Where Hoven fits

If you'd rather have someone look over your shoulder — or figure out which of your tools are actually worth replacing — that's what I do. Most clients start with a $999/day audit (most take 1–5 days), and you get a prioritized plan plus a "don't build this" list, and if it isn't worth more than you paid, you don't pay. Details on the pricing page, or get in touch.