How Much Does It Cost to Run an App Built With AI?

The server behind Unfinished, the app we built with Codex, was listed at $7 a month. That looks cheap enough, but we were still asking Codex to change the app, checking its work and fixing things that had passed the tests. Anyone budgeting for the same experiment needs to count that part too.

We used Codex through our usual ChatGPT subscription. That means the app shares an existing expense with our other work, although long development sessions can still use up the allowance.

Quick Answer

Our server and 1 GB disk come to $7.25 a month at the listed rates, with email and any additional service usage on top. We used our existing ChatGPT subscription for Codex, so its full price should not be added as a new app-only expense. Further development uses that shared allowance and our time; any credits or upgrades bought for the app would add to its cost.

Our Monthly Costs

Unfinished is a small, invite-only web app for tracking client work, approvals and unpaid invoices. We tried it with three informal testers.

Render lists persistent disks at $0.25 per GB per month, giving us the $7.25 server-and-storage subtotal. Its workspace fee is separate. These are full-month USD list prices before tax, credits and additional usage, not a completed bill.

SQLite keeps our database in the same hosting budget. The attached disk also limits this setup to one server instance, so expanding to several servers would require more than paying for extra storage.

Our ChatGPT Subscription

We used the ChatGPT subscription we already have for our other work. Codex was part of that account, so charging the entire subscription to Unfinished would make the app look more expensive than the extra cash we spent on it.

That does not make the development unlimited or costless. A long session can use up allowance that would otherwise go to another project. OpenAI’s billing documentation distinguishes included usage, additional credits and separately billed API access: exhausting allowance and spending more money are not the same event.

For our breakdown, we would show the subscription as a shared expense and identify any credits or upgrade bought specifically for the app. Someone buying a subscription solely to build their own app should count the full price for the months they keep it. We have not measured Unfinished’s share of our existing subscription.

Model choice and the amount of work matter too. Repeated revisions, long conversations and demanding tasks can consume more allowance than a small repair; our model ranking and token-cost comparison explains why the model and effort setting deserve attention.

Render hosts the deployed code independently of our ChatGPT subscription, and we return to Codex when we want help changing the app. If an app itself calls a paid AI model during use, those requests belong in its operating costs.

What Changes as More People Use It?

The bill can increase because more people use the app or because we keep changing it.

Email has a useful catch. Resend’s free plan allows 3,000 messages a month but only 100 a day. A hypothetical launch with 150 registrations needing one verification email each would already exceed that daily allowance. Pro starts at $20 a month for 50,000 messages without the daily quota, making the server, disk and that email plan $27.25 a month before development costs.

Our app sends account emails; it does not send the client payment reminders it helps users prepare. The features you enable determine how quickly you use that allowance.

Render’s Hobby workspace includes 5 GB of monthly outbound bandwidth, then $0.15 per extra GB, shared across its services. Its 500 included build minutes can also be consumed by repeated deployments while the audience stays the same. Neither limit translates into a dependable number of users without knowing their activity.

Fixing and Updating the App

Our first live backup restore failed because the script expected an account-deletion record that did not exist. We supplied an empty file to complete the restore, and Codex later added a code fix and tests locally. That meant more work with the tool, plus someone attempting the restore and checking the result.

We also found a local form that would not save because an older server process was running behind a newer interface. Paying for hosting did not remove the need to investigate it, and an AI-generated test result had not caught the problem in the running app.

These are reasons to budget for maintenance. Our app-security checklist covers checks worth repeating when accounts or access rules change. We did not measure the repair hours in this experiment, so there is no defensible labour total to add yet.

For someone considering the same route, I would budget for a month of continued development alongside the hosting, then compare that estimate with the subscription, extra usage and repair time recorded. Our server is inexpensive; whether the app stays inexpensive depends heavily on how much work we keep putting back into it.