Vibe coded your SaaS? Don't wake up to a $6,000 bill

Something remarkable is happening. With an AI coding agent, people who have never shipped software are building real SaaS products in a weekend, launching them on X and getting paying customers. Designers, marketers, students, founders who used to need a technical co-founder. Software is being democratized, and a lot of what's being built is genuinely great.

There's one problem nobody warns you about. Your coding agent built exactly what you asked for: sign-up, free credits, a trial, a payment page. It almost certainly didn't add the part that stops one person from claiming all of that through a hundred accounts, because you didn't ask, and it doesn't know your bill is on the line.

What new founders are waking up toCopy Anchor Link

These are real stories from teams in our early beta, from before they had protection:

• A team woke up to a $6,000 OpenAI bill. Someone had created hundreds of free accounts and used up the complimentary AI credits on every one of them.
• A team whose cloud bill normally ran $200 to $300 a month woke up to a $12,000 bill. Automated registrations had triggered thousands of expensive serverless functions, database operations and background jobs overnight.
• A bot used one team's phone verification to send 100,000 one-time passcodes. With no bot protection in place, the team paid for every one of those text messages.
• Fake users drained one team's shared model provider quota. Their paying customers couldn't use the product until the team raised its budget to cover the abuse.

None of these founders did anything unusual. They launched, people came, and some of those people were scripts.

The gaps AI-built apps usually ship withCopy Anchor Link

1. Free credits granted the moment an account exists, with no check on whether this person already had them.
2. Expensive work on sign-up: AI calls, background jobs and emails that run before you know the account is real.
3. No limit on paid verification: text messages or emails that a bot can trigger thousands of times.
4. One shared AI key with no spending cap, so free users and paying users drain the same budget.
5. No memory of who already claimed, so every new email address looks like a brand-new person.

AbuseZero fixes the first and the last: it checks every free credit, trial and free-plan claim against everyone who already received it, and returns allow or deny. The middle three are settings and design choices in your own app and your providers, and we cover them in the indie hacker's launch checklist.

Fix it with the agent that built itCopy Anchor Link

You don't have to learn abuse prevention from scratch. Connect the AbuseZero MCP server to your coding agent, and ask it to do the work. Prompts that work well:

Find every place in this codebase where a user receives free credits,
starts a trial, gets a free plan or redeems a discount. List them with file names.

For each one, create an AbuseZero benefit in observe mode, once per user.
Use the Strict protection level for free credits and Balanced for the trial.

Add an AbuseZero evaluation before each grant. Handle allow, deny and skipped.
On deny, show a neutral message and don't grant anything.

Add the AbuseZero browser SDK to the sign-up page and send the device token
with each evaluation.

Review what the agent changes, like any other change. Start in observe mode so nothing is blocked while you check the results, then switch to protect. The agent works only with the permissions you approve, and every AbuseZero tool is labeled as read-only, changing or permanent.

Three moves that save most new foundersCopy Anchor Link

• Cap. Set a hard spending limit and alerts with your AI provider and your cloud host. A bad night then has a ceiling.
• Defer. Don't run expensive work until you know an account is real, for example after email confirmation or after the AbuseZero check allows the claim.
• Check. Evaluate every free credit, trial and free-plan claim before you grant it. That's AbuseZero's job.

More on the money side in why new SaaS founders wake up to surprise bills.

Frequently asked questionsCopy Anchor Link

Do I need to know how to code to use AbuseZero?Copy Anchor Link

Not much. If an AI coding agent built your app, it can add AbuseZero through the AbuseZero MCP server. You review the changes and decide when to turn protection on.

Will AbuseZero slow down my app?Copy Anchor Link

It's one server-side call when someone claims a benefit, and it returns within its time limit. For trials you can take back, you can even start the trial at once and check in the background. See zero-wait free trials.

What does it cost?Copy Anchor Link

Builder is pay as you go, with no subscription. Every evaluation uses credits. See the pricing page for current rates.

What if my coding agent makes a mistake?Copy Anchor Link

Start every benefit in observe mode. Every claim is still allowed while AbuseZero records what it would have decided, so you can check the results before anything is blocked.

Protect what you builtCopy Anchor Link

Keep readingCopy Anchor Link

• Going viral on X? Protect your free tier before launch day
• The indie hacker's launch checklist for abuse and surprise bills
• Why new SaaS founders wake up to surprise bills
• How to protect signup credits in an AI app