# What is a request body?

> The request body is the data a form or app sends inside a web request, often as JSON. How a Lovable form's body reaches n8n and how to read it.

Source: https://learn.ynteractive.com/content/glossary/request-body · Updated 2026-10-01 · Free from Stepthrough (https://learn.ynteractive.com)

[Web apps](https://learn.ynteractive.com/content/glossary#topic-web-apps) · [AI glossary](https://learn.ynteractive.com/content/glossary)

Updated October 1, 2026 · By [Robert Breen](https://learn.ynteractive.com/content/about)

A request body, often called the payload, is the actual data carried inside a web request: the name, email and message someone typed into a form, packed up and sent to another system. The rest of the request (address, method, headers) says where it goes and how; the body is what is being sent.

## Why it matters for a small business

When you connect a form to an automation, the body is the part you care about. Everything the customer typed travels in it, usually as [JSON](https://learn.ynteractive.com/content/glossary/json): a set of named keys with values. If the keys the form sends don't match the keys the workflow reads, nothing errors loudly; the workflow just gets blanks. So knowing the exact key names is the whole job.

It also explains a detail that confuses people in n8n. A webhook receives the whole request, not just the form fields, so the fields sit inside a part called body. That is why the expressions read `$json.body.name` rather than `$json.name`.

## In a real lesson: Lovable + n8n: Build a Web App with an AI Backend

In the [Build a Web App with an AI Backend lesson](https://learn.ynteractive.com/content/lovable-n8n-web-app-ai-backend), you describe a contact form to Lovable for a made-up marketing business. The prompt you paste spells out the body: "The data should be sent as JSON with keys: name, email, question, feedback." Those four keys are the contract between the form and the workflow.

In n8n, the form's data arrives at the **On webhook call** trigger. In the AI Agent, you choose **Define below** as the prompt source and paste a template that reads each key from the body: `Name: {{ $json.body.name }}`, then the email, question and feedback the same way. The agent gets a tidy, labeled message no matter what the visitor typed.

When you test from Lovable's **Preview** with **Fill with test data** and **Send Message**, the body travels to n8n, the agent saves the lead to the **Leads** sheet and replies by Gmail, and the **Respond to Webhook** node tells the form it worked.

[Try this lesson free](https://learn.ynteractive.com/modules/lovable-n8n) or [read the step-by-step guide](https://learn.ynteractive.com/content/lovable-n8n-web-app-ai-backend).

## Common confusions

### Request body vs URL

The [webhook](https://learn.ynteractive.com/content/glossary/webhook) URL says where the data goes. The body is the data itself. Never put private details in the URL; it can end up in logs and browser history.

### Request body vs response

The body goes from the form to n8n. The response is what n8n sends back, like the success message the form shows.

## Tips

- List the exact JSON keys in your app-builder prompt, in lowercase, with no spaces.
- Run one test and look at the webhook's output to see the body's real keys.
- If a field shows up blank in n8n, compare the key spelling on both sides first.

## Related terms

[JSON](https://learn.ynteractive.com/content/glossary/json) · [Webhook](https://learn.ynteractive.com/content/glossary/webhook) · [Web form](https://learn.ynteractive.com/content/glossary/web-form) · [Expression](https://learn.ynteractive.com/content/glossary/expression) · [Respond to Webhook node](https://learn.ynteractive.com/content/glossary/respond-to-webhook) · [HTTP method (GET vs POST)](https://learn.ynteractive.com/content/glossary/http-method)

## Where you use it: free lessons

- [Lovable + n8n: Build a Web App with an AI Backend](https://learn.ynteractive.com/content/lovable-n8n-web-app-ai-backend) (Lovable and n8n, 15 min)
- [Build an AI Emergency Request Form for Your Plumbing Company](https://learn.ynteractive.com/content/plumbing-emergency-request-form-ai-lovable-n8n) (Lovable and n8n, 15 min)
- [Build an Expense Reimbursement Form With AI Policy Checks](https://learn.ynteractive.com/content/expense-reimbursement-form-ai-approval-lovable-n8n) (Lovable and n8n, 15 min)

## More free tutorials

[Lovable tutorials](https://learn.ynteractive.com/content/tool/lovable)

## Frequently asked questions

**Why is my form data under body in n8n?**

The webhook trigger outputs the whole request, with headers, query and body as separate parts. The form fields are in body, so you read them as `$json.body.fieldname`.

**What is the difference between a payload and a request body?**

In everyday use they mean the same thing: the data a request carries. "Payload" is just the more casual word.

[All AI glossary terms, A to Z](https://learn.ynteractive.com/content/glossary) · [Free prompt templates](https://learn.ynteractive.com/content/prompts)