Cap your AI bill

Set a hard spend limit on your OpenAI project

• Use a separate project (and key) for each app, so one app can't use up another's budget.
• In Project settings, open Limits, then Spend, select Edit spend limit and enter a monthly spend limit.
• Turn on “Enforce a hard limit”. A spend alert alone only sends a notification; requests keep going.
• Add spend alerts below the limit, so you hear about unusual use before the limit stops your app.
• Handle the 429 error (project_spend_limit_exceeded) in your app with a friendly message instead of a crash.

OpenAI says enforcement isn't instant, so spend can go slightly over the limit.

Set a spend limit on your Anthropic workspace

• Create a workspace for this app in the Claude Console. The Default Workspace can't have a spend limit.
• On the Workspaces page, select the workspace, click Spend limits, set a monthly cap and turn on alerts at the thresholds you want.
• Use an API key scoped to that workspace in this app.
• Check your organization's own limits too: they always apply, even if workspace limits add up to more.

Set a project spend cap in Google AI Studio

• Use a separate Google AI Studio project for each app, since every key in a project counts toward that project's cap.
• In AI Studio, open the Spend page, then Monthly spend cap, and select Edit spend cap.
• If you use Prepay with auto-reload, set a Monthly auto-charge limit under Manage auto-reload on the Billing page.
• Check Dashboard, then Usage, after you launch, to see what your app actually uses.

Google marks project spend caps as experimental and says spend can run over for about 10 minutes.

Set a credit limit on your OpenRouter key

• On your key's page, set a credit limit, with a daily, weekly or monthly reset if you want one. OpenRouter recommends a limit on every key.
• Use one key per app, so you can see and cap each app's spend.
• Keep keys with no limit out of browser code, and rotate a key right away if you think it leaked.