A lot of people dream of making web apps, but most don't. I recently saw how a developer made an online PDF editor in about two weeks. The site, pdfsimple.xyz, is up and running, and people are paying to use it. The AI stuff only cost about $72.
This shows how pretty much anyone can use AI to make a SaaS product in 2025 or 2026 without spending too much time or cash.
Here's what he did, so you can see what Replit AI Agent can really do.
What Did He Make?
It's a simple online PDF editor that lets you:
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Upload PDFs by dragging and dropping
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Add text, signatures, images, check boxes, dates, highlighting, and fill out forms
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It's cheaper than Adobe Acrobat:
- $1 for a full day
- $5 a month
- $50 a year
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You can log in with Google in one click
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It has all the pages you need: a homepage, a pricing page, a login, a dashboard, an editor, and pages to handle your account and payments.
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It uses Stripe for payments (so you can make invoices, use coupons, and check your payment history)
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It's hosted at pdfsimple.xyz
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Basically, it's a real product that people can use, not just a demo.
How Did He Build It?
First, he figured out what he wanted to build (with ChatGPT)
He asked ChatGPT, I want to make a simple PDF editor that costs $5 a month. What tech do I need? How hard is it? What should I include in the first version?
- He got ideas for what to include, which tech to use, and how to build each part.
Then, he designed the website (using Replit Design Agent)
He needed these pages:
- Homepage (where you can drag and drop a PDF)
- Pricing page
- Login page
- Dashboard for your files
- The PDF editor itself
- Account and payment settings
He told Replit's Design Agent what he wanted, and it made designs in about three minutes (which cost less than a dollar).
- If he didn't like the designs, he could show it examples from Dribbble to change the style.
The hardest part was turning the designs into a working app.
For this, he used a better AI agent, using the High/Max Autonomous mode. It's not cheap, but it tests things automatically.
He would:
- Start with a Master Prompt that explained everything (helped by ChatGPT).
- Find problems by taking screenshots of errors and telling the agent what he wanted to happen.
- If things went wrong, he could go back to older versions (Replit is good at this).
- For small fixes, he used the Fast Agent because it was faster and cheaper.
The main problems were:
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The PostgreSQL database (Replit has this built-in, so it was easy)
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Google login (also easy with Replit)
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The Stripe payment system (this was tricky, but Replit helped set up products and prices automatically).
Before launching, he did a security check and got a domain name
- Replit has a Beta security scanner that finds common problems.
- He bought the domain right on the platform (pdfsimple.xyz was super cheap).
- He waited for the domain to connect (about 20-30 minutes).
- In total, it took about two weeks, working a few hours each day.
- The AI cost about $72.
What's Good and Bad About Replit AI Agent (as of January 2026)?
Good stuff:
- It's great at going from design to a working app.
- It has PostgreSQL , Stripe, and Google Auth built-in and ready to go.
- You can go back to older versions (this is super helpful).
- You can buy and connect a domain name in one place.
- It has basic analytics built-in.
- It does security scans (which is reassuring).
Bad stuff:
- PDF stuff (dragging, adding notes, rendering, saving) can be buggy.
- It can forget what's going on in big projects (so you might need to start new chats).
- It can misunderstand what you want, so you need to be clear and patient.
- It can get expensive (while $72 for this project is great, using Max Agent a lot could cost hundreds or thousands).
How to Use It Best:
- Start with the Design Agent to design all your pages (this should cost only a few bucks).
- Write a long, clear description of what you want (use ChatGPT or Claude to help).
- Use the High/Max Agent to build the basics (database, login, payment, core features).
- Use the Fast Agent for small fixes to save money.
- Save a stable version after each big feature is done, so you can go back if needed.
- Be ready to report errors, take screenshots, and describe problems (this takes the most time).
Conclusion
Basically, Replit AI Agent is great for people who don't know much about coding but want to make something like designers and product managers. It lets someone with little coding skills build a working product that makes money for only a few bucks, if they're willing to spend time fixing problems with the AI.
If you just want to see AI help you code, run, and put your project online, Replit is already great. But if you want to make a product that people will pay for, it's a helpful tool, but it's not magic. You still need programmers.
What do you think? How much better can AI full-stack agents like Replit get in the next year? Will they be better than real programmers?