Which JSON Content-Type to Use in Node.js

Written: August 14, 2026

For JSON APIs, the standard Content-Type is application/json. That tells clients and servers to parse the body as JSON rather than plain text or form data.

In Express, set the header on responses and rely on express.json() (or equivalent) to parse incoming JSON bodies.

Response header example

res.set('Content-Type', 'application/json');
res.status(200).send(JSON.stringify({ ok: true }));
// or simply:
res.status(200).json({ ok: true });

Request parsing

const express = require('express');
const app = express();
app.use(express.json()); // reads application/json bodies
app.post('/api', (req, res) => {
  res.json({ youSent: req.body });
});

Avoid text/json or inventing custom types unless you have a documented legacy constraint. Stick to application/json for modern APIs.

Quick checklist

• Send Content-Type: application/json; charset=utf-8 when relevant

• Pair it with Accept: application/json on clients that care

• Validate JSON shape after parsing—headers alone are not security