---
title: "Machines & sign-in"
description: "Every install belongs to your account: how a machine is paired, why one profile may only run on one machine at a time, how a takeover works, and what happens when a machine is removed."
canonical: "https://scalebrowser.net/docs/account/machines"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://scalebrowser.net/llms.txt
> Use this file to discover all available pages before exploring further.

# Machines & sign-in

> Every install belongs to your account: how a machine is paired, why one profile may only run on one machine at a time, how a takeover works, and what happens when a machine is removed.

Every install signs in once and becomes a **machine** on your account. That is where two limits are counted, and where one safety rule lives that is not a limit at all.

## Pairing
The desktop app does it: press **Sign in**, a browser window opens, you sign in, and it closes by itself.

A daemon you run without the desktop app has no window, so it carries a **pairing token** instead:

<Steps>

<Step title="Generate a token">

Open [Settings, API tokens](/settings/api-tokens) and press **Generate token**. The value is shown once.

</Step>

<Step title="Hand it to the daemon">

As `SCALEBROWSER_API_TOKEN`, next to the other two secrets. See [Install & run](/docs/install#configuration).

</Step>

<Step title="Forget about it">

The token is used once, at enrolment. From then on the daemon holds its own credential, encrypted in the data directory.

</Step>

</Steps>

Without it, every profile start is refused with `4011`.

<Note>

**The account comes from the session, never from the pairing code.** If a code and a session name different accounts, the pairing is refused and the code is burned. Otherwise a code somebody looked over your shoulder to read would be enough to attach their machine to your account.

</Note>

## One profile, one machine
Independent of any plan limit: **a profile runs on one machine at a time.**

Starting it on a second machine of the same account is refused with `4012`, and the message names the machine holding it.

This is not a licence restriction. One identity signed in from two places at once is what a relying party reads as a cloned account, which is the exact outcome the whole product exists to avoid. It applies whether or not you use sync.

### Taking it over
If the other machine is at home and you are not, take the profile over. The takeover **revokes** the holder's right rather than deleting its row: the holder learns about it from the answer to its own heartbeat, closes the browser and releases the profile.

<Warning>

**A revoked row still blocks until the holder actually releases it.** Between the order and the closing lies up to one heartbeat, and that gap is exactly the double operation the rule exists to prevent. Wait for it.

</Warning>

## How a copied machine is caught
Copying a whole data directory copies the key and the token together, so two machines would otherwise run under one identity with nothing noticing. Three things catch it, and none of them alone is enough:

**The proof rotates.** Every renewal **swaps** the credential rather than extending it. A second presentation of an old one is a reuse.

**A counter climbs.** It rides in the payload and in the signature. Two instances under one identity contradict each other in it, even if they take turns.

**The row is read on every call**, not only when a credential is issued. That is why a revocation bites within minutes rather than at the next renewal.

<Warning>

**When a clone is found, the whole family is revoked.** Nobody can tell which of the two machines is the real one, so neither keeps working silently. Both have to pair again, and you are told.

</Warning>

## Removing a machine
[Settings, Devices](/settings/devices) lists them and removes one.

Removal bites immediately. A removed machine does **not** get the outage grace window, because that window is for a control plane nobody can reach, and handing it to a machine that was explicitly refused would hide the removal for hours behind a screen still saying the account is connected.

Signing in again on that machine re-enrols it. A fresh pairing token reopens the door; an unchanged one does not.

## What a machine costs
One machine slot. See [Plans & limits](/docs/account/plans) for how many each plan carries, and the add-on for buying more.

Browsers are counted separately, across all your machines together.

## Next
- [Plans & limits](/docs/account/plans): the two numbers a subscription sells.
- [Profile sync](/docs/sync): moving a profile between machines you own.
- [Errors](/docs/errors): `4011` and `4012` in context.
- [Remote access](/docs/agents/remote): why a connector belongs to exactly one machine.