# Sessions & billing

## Threads

Your plan gives you a number of **threads** — concurrent capacity for running browsers. Each session takes one or more threads depending on its type:

| Session type | Threads | How it's chosen |
| --- | --- | --- |
| Linux headless | 1 | `headless` set to a headless value for that browser |
| Linux headful | 2 | the default: a full display, harder to detect |
| Mobile WebView | 3 | Android WebView on hardware phones / iOS WebView (early access) |
| Mobile Chrome | 4 | Chrome and other full browsers on hardware Android phones (early access) |

The launch response tells you the session's `resource_class` and `weight`. If a launch would take you over your threads, it's refused with `429 threads_exceeded` until a session closes.

**More memory:** `"memory": 2`, `3` or `4` multiplies the session's memory limit and its threads by that number — a headless session with `"memory": 2` takes 2 threads and twice your plan's memory, a headful one 4 threads. Use it for memory-heavy pages instead of splitting the work ([memory option](https://cdpfleet.com/docs/options/memory)).

**Launch rate:** threads ÷ 5 launches per second and threads × 6 per minute, at least 2 and 10; dedicated threads get twice that. Above it a launch returns `429 rate_limited` with `Retry-After`. For many short pages, keep one session and open a fresh context per page instead of launching a browser each time.

## Dedicated and shared threads

**Shared threads** are pooled capacity for bursty and scheduled work. Each purchased thread contributes browser-minutes per day to your shared account pool (60, 120, 240 or 480, by product), and at most 25% of the daily pool can be used in any rolling 60 minutes. **Dedicated threads** are reserved capacity for continuous use, with no daily or hourly limit. Both let you run as many browsers at once as you have threads. See [Plans & pricing](https://cdpfleet.com/docs/pricing).

Minutes are counted per thread, like threads themselves: a headful browser takes 2 threads, so each minute it runs uses a minute from each of them. That is no extra charge, only the minutes of the second thread it occupies.

### Shared leases

Shared sessions run on 15-minute leases that renew automatically while shared capacity allows — a lease is not a time limit, and a session is never restarted on purpose. Only when the shared fleet is full and other shared launches are waiting may the longest-running shared sessions not be renewed at their next 15-minute mark. Such a session ends with reason `lease_reclaimed`: its browser is terminated and its slot released. Browsers are never reused between customers. Dedicated sessions have no leases.

## Metering

-   Usage is **thread-seconds**: threads × seconds. A headful session running 3 min 12 s uses 6 min 24 s of thread time. Nothing is rounded up.
-   The clock starts when your browser is ready (the launch response) and stops when either side closes the WebSocket.
-   A session you never connect to ends after 60 seconds and is metered until then.
-   If you try to connect and our server doesn't accept the connection, that session isn't billed at all.
-   The shared daily pool resets at **midnight UTC**, with no carry-over. A session running over midnight is split between the two days.
-   The rolling-hour limit looks at the last 60 minutes at any moment, not at clock hours.

## When a session ends

-   You call `browser.close()` or your client disconnects — the session ends at once. A `wsUrl` can't be reused.
-   `inactivity_timeout` passes with no traffic: 120 s by default. Ask for up to 10 minutes on shared threads, 5 on Community and 24 h on dedicated; idle minutes are billed like any others.
-   `overall_timeout` is reached, capped by your plan's maximum session length (24 h) and, for shared threads, your remaining daily minutes.
-   You or an admin ends it from the dashboard or the [Account API](https://cdpfleet.com/docs/api), or your shared daily or rolling-hour pool runs out.
-   A shared lease is not renewed because the shared fleet is full (`lease_reclaimed`, see above).

Your usage and every session's start, end and duration are in the [dashboard](https://cdpfleet.com/app) and the [Account API](https://cdpfleet.com/docs/api).

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Source: https://cdpfleet.com/docs/sessions · Markdown: https://cdpfleet.com/docs/sessions.md · All docs for AI tools: https://cdpfleet.com/llms.txt