Vercel bill spike from image optimization or functions

Spend Management notifications at 50%, 75% and 100% of your amount

# and, if you turned on pausing, visitors get:
503: DEPLOYMENT_PAUSED

Why it happens

Image Optimization is billed per transformation (each cache miss or stale revalidation) plus cache reads and writes. Every extra width, format and quality multiplies the variants. Next.js warns that loose remotePatterns (for example leaving out the path, which implies a ** wildcard) may let other people optimize images you never intended.

Functions cost active CPU time and memory time. Bots crawling dynamic pages, routes with no caching, and functions that run until the timeout add up fast.

Fix it by hand

1. Find the metric. In the dashboard open Usage, switch to the last 30 days, and break it down by project. Note whether Image Optimization, Functions or data transfer jumped.
2. Set a ceiling. On Pro, go to Settings, Billing, Spend Management. Set the On-Demand Budget and enable Pause Production Deployments. Setting an amount alone doesn't stop usage, and Vercel checks every few minutes, so set it a little below your real maximum.
3. Tighten images. Restrict remotePatterns to your exact host and path:

   images: {
     remotePatterns: [new URL('https://cdn.example.com/my-account/**')],
     formats: ['image/webp'],
     qualities: [75],
     minimumCacheTTL: 2678400, // 31 days, for images that rarely change
   }

   Trim deviceSizes and imageSizes to the widths you use, and mark tiny icons unoptimized per image.
4. Rate limit expensive routes. In Firewall, add a rule with the Rate Limit action for your API or search routes. WAF rate limiting is available on all plans.
5. Cap function time. Set a sensible maxDuration per route, cache responses that don't change per user, and look for functions that call themselves.

Stop it happening again

• Keep Spend Management on with pausing enabled, at an amount you can afford to lose.
• Review remotePatterns whenever you add an image source.
• Add a rate limit rule to any route that calls a paid API or a database.