The problem: Zod (the most popular validation library) doesn't have FormData support. It's their #1 requested feature with 60+ upvotes on GitHub [1], but they haven't implemented it.

So every Server Action looks like this:

    const name = formData.get('name') as string;
    const age = parseInt(formData.get('age') as string);
    // ... manual validation

    const result = validateFormData(formData, schema);
    // Automatic type conversion, validation done

Zero dependencies. 3KB. MIT licensed.

GitHub: https://github.com/YOUR_USERNAME/lite-schema-check npm: npm install lite-schema-check

Technical details in README. Happy to answer questions about the implementation.

[1] https://github.com/colinhacks/zod/discussions (search for FormData)