What does MERN stack maintenance cost per year?

MERN stack maintenance typically costs 15 to 25% of the original build cost per year. For a $50,000 MERN build, that is $7,500 to $12,500/year covering Node.js and npm package security patching, React and Next.js upgrades, MongoDB Atlas driver updates, Sentry monitoring, Atlas Performance Advisor review, and bug fixes. A dedicated MERN developer at $3,200/month covers maintenance plus ongoing feature work, which is usually better value than a separate maintenance retainer.