Web Serial API: navigator.serial device access

Limited availabilityNot supported in Firefox (Android), Safari (macOS), Safari (iOS)WICG draft

In one line: the Web Serial API lets a page ask the user to pick a serial port with navigator.serial.requestPort(), then read and write bytes through the returned SerialPort’s readable/writable streams. MDN marks the Serial interface not Baseline — “because it does not work in some of the most widely-used browsers” — and exposes it only in secure contexts.

Requesting and reusing a port

const port = await navigator.serial.requestPort();
await port.open({ baudRate: 9600 });

Per MDN, requestPort() “must be called via transient activation” — trigger it from a click handler or similar user gesture, not automatically on load. navigator.serial.getPorts() returns an array of the currently connected ports the origin already has permission to access, without prompting again:

const ports = await navigator.serial.getPorts();

Access can also be blocked by the serial Permissions Policy; per MDN, a blocked page never shows the device picker and the user is not prompted.

Where it is supported

Per the compatibility data above, desktop Chrome and Edge have supported the API since version 89, and desktop Firefox added support later, at version 151. Safari does not support it on macOS or iOS. On Android, Chrome has full support from version 148 per MDN browser-compat-data; in Chrome 138-146 serial ports there were “only available if they are provided by Bluetooth RFCOMM serial port emulation”. Firefox for Android does not support it.

Reading and writing

const reader = port.readable.getReader();
try {
  while (true) {
    const { value, done } = await reader.read();
    if (done) break;
    console.log(value);
  }
} finally {
  reader.releaseLock();
}

navigator.serial also fires connect and disconnect events — bubbling from SerialPort — so a page can react when an already-authorized device is attached or removed instead of polling getPorts().

How to detect it at runtime

async function connectSerial() {
  if (!('serial' in navigator)) {
    // Web Serial unsupported here — fall back to WebUSB, or point the user at a
    // native companion app instead of calling navigator.serial.
    return null;
  }
  const port = await navigator.serial.requestPort();
  await port.open({ baudRate: 9600 });
  return port;
}

What goes wrong

• requestPort() requires transient activation — call it from a click handler, not automatically on page load, or the returned promise rejects.
• Feature-detect 'serial' in navigator before calling anything on it; MDN marks Web Serial not Baseline, so absence is expected in some browsers.
• Serve the page over HTTPS — the Serial interface is exposed only in secure contexts.
• On Android, check the Chrome version before assuming USB-connected devices are reachable — per MDN browser-compat-data, Chrome 138-146 covered Bluetooth RFCOMM emulation only; 148+ is full.
• Call getPorts() on load, before falling back to requestPort(), to reuse a previously granted port without a new prompt.
• A page can also be blocked from prompting at all by the serial Permissions Policy — check for that failure mode separately from a user simply declining.

Where to go next

• WebUSB API — the related reference for USB devices not claimed by an OS driver.
• WebHID API — the related reference for USB HID class input devices.

Specifications

Specification	Status
Web Serial API	WICG draft

• Legend
• Yes
• Partial
• Flag
• No
• Unknown

Browser / Platform	Support	Versions	Confidence	Source	Notes
Chrome (Desktop)	Yes	89	high	source	—
Chrome (Android)	Yes	148	high	source	—
Edge (Desktop)	Yes	89	high	source	1
Firefox (Desktop)	Yes	151	high	source	—
Firefox (Android)	No	—	high	source	2
Safari (macOS)	No	—	high	source	3
Safari (iOS)	No	—	high	source	45
Samsung Internet	Partial	30.0	high	source	67
WebView (Android)	No	—	high	source	8

1. Derived by browser-compat-data mirroring from Chrome.
2. No Firefox for Android support is recorded in browser-compat-data.
3. No Safari support is recorded in browser-compat-data.
4. No Safari on iOS support is recorded in browser-compat-data.
5. Derived by browser-compat-data mirroring from Safari.
6. Serial ports are only available if they're provided by Bluetooth RFCOMM serial port emulation.
7. Derived by browser-compat-data mirroring from Chrome Android.
8. Implementation tracking: https://crbug.com/40740509.

Source data: /compatibility/web-serial.json · Global usage: 72 % (StatCounter 2026-05)

Source: spec · MDN · Last verified 2026-10-03 · Confidence: high (computed from sources)