React Form Backends Compared: Serverless Functions vs. Form-as-a-Service

React Form Backends Compared: Serverless Functions vs. Form-as-a-Service React makes building a form straightforward. What happens after onSubmit is a different question: you still need somewhere to validate, process, store, or forward the submission. Two common approaches are writing a serverless function yourself or using a hosted form backend such as onsubmit.dev (form backend). This article compares the two, using Vercel/Netlify-style functions for the DIY approach and onsubmit.dev with its React integration as the managed example. The basic problem Imagine a typical contact form: function ContactForm () { return ( < form > < input name = "email" type = "email" required /> < textarea name = "message" required /> < button type = "submit" > Send </ button > </ form > ); } The React component is only the UI. A real application usually needs backend behavior too: accepting the HTTP request validating and sanitizing input handling errors preventing abuse or spam delivering or storing the submission keeping credentials and other secrets off the client There are two broad ways to get that backend. Option 1: Build a serverless function With platforms such as Vercel and Netlify, you can create an HTTP function alongside your application and have your React form submit to it. Conceptually, the architecture looks like this: React form | v Your serverless function | +--> validation +--> email provider +--> database +--> other services The main advantage is control. Your function owns the request lifecycle, so you decide precisely how data is validated, transformed, authenticated, stored, and forwarded. If a submission needs to update PostgreSQL, call an internal API, enqueue a job, and return application-specific data, a custom backend is usually the natural solution. Serverless functions can also reduce product-level vendor lock-in. Although platforms have their own deployment conventions, HTTP handlers and their business logic are generally portable with some work. The tr