For form validation, I used yup — what other validation libraries have you looked at?

Besides yup, the following libraries are often used for form validation in frontend:

• Formik — a popular library for managing forms, often used together with yup for validation.
• React Hook Form — a lightweight and performant library, supports integration with yup and other validators.
• Joi — a powerful schema validation library, originally for Node.js, but can also be used in the browser.
• Validator.js — a set of functions for string validation, suitable for simple cases.

The choice depends on the project requirements and technology stack.