Conform is a type-safe form validation library designed to enhance native HTML forms through progressive enhancement. By leveraging web fundamentals and the FormData API, it provides a seamless experience for managing form state, validation, and accessibility. It is architecture-agnostic, working effectively with server-side frameworks like Remix and Next.js, while allowing developers to maintain control over their HTML markup. The library focuses on performance and developer experience by enabling fine-grained subscriptions and automatic type coercion. The core philosophy of Conform is to treat HTML forms as the source of truth, avoiding the pitfalls of over-abstracting form state within React. By syncing data through event delegation, it remains compatible with any standard HTML form, ensuring that form submissions remain robust even if client-side JavaScript fails or is slow to load. It integrates directly with schema validation libraries like Zod, Valibot, and Yup to provide type-safe field inference and automatic constraint generation. Developers can define schemas once and use them for both client-side validation for instant feedback and server-side validation to ensure data integrity. Some of the key features are:

• Progressive enhancement first: Builds upon native HTML form behaviors to ensure functionality without relying solely on client-side JS.
• Type-safe field inference: Automatically infers field types based on the schema, reducing the need for manual type definitions.
• Fine-grained subscription: Optimizes re-renders by allowing components to subscribe only to specific field updates.
• Built-in accessibility helpers: Generates unique IDs and manages ARIA attributes automatically for accessible form inputs and error messages.
• Automatic type coercion: Integrates with libraries like Zod to handle string-to-type conversion for form data.
• Intent-based controls: Uses declarative intents to manage dynamic form operations such as adding, removing, or reordering list items.
• Comprehensive validation modes: Supports server-only, client-side, and async validation strategies to balance performance and latency.

Operationally, Conform uses a useForm hook as the primary entry point to manage the form state, validation metadata, and submission lifecycle. It handles complex form structures like nested objects and arrays using a standard naming convention, which makes managing dynamic lists straightforward. By returning submission results from server actions or loaders, Conform can easily re-populate form fields, display server-side errors, and manage focus after validation failures. The API is designed to be minimal, exposing utility functions like getFormProps, getInputProps, and getFieldsetProps to offload the burden of boilerplate attribute configuration from the developer. Common use cases include:

• Complex form management: Building multi-step forms or forms with dynamic fields, such as adding or removing tasks in a list.
• Server-rendered applications: Enhancing standard HTML forms in frameworks like Remix or Next.js with robust validation and error handling.
• Accessible UI creation: Ensuring that all form inputs, radio groups, and checkboxes meet WCAG standards by managing ARIA relationships automatically.
• Unified validation logic: Defining a single Zod schema that enforces rules on both the client for instant UI feedback and the server for secure request processing.