# Session replay

> https://docs.errora.org/en/products/session-replay

Session replay records what happened in the browser — DOM mutations, clicks, navigation,
console — and plays it back next to the error it produced.

## Setup

```javascript
import * as Sentry from "@sentry/browser";

Sentry.init({
  dsn: "https://<public_key>@<your-errora-host>/<project_id>",
  integrations: [
    Sentry.replayIntegration({
      maskAllText: true,       // privacy defaults: on
      blockAllMedia: true,
      maskAllInputs: true,
    }),
  ],
  replaysSessionSampleRate: 0.1,   // 10% of all sessions
  replaysOnErrorSampleRate: 1.0,   // 100% of sessions that hit an error
});
```

Two sample rates, deliberately:

- `replaysSessionSampleRate` — ordinary browsing. Keep it low; every recorded session costs.
- `replaysOnErrorSampleRate` — sessions where an error happened. Keep this at `1.0`: this is
  the recording you will actually want to watch.

## Privacy

Replay records your users' screens, so treat it as sensitive by default:

| Control | Effect |
| --- | --- |
| `maskAllText: true` | Text nodes are replaced with blocks |
| `maskAllInputs: true` | Input values never leave the browser |
| `blockAllMedia: true` | Images/video are not recorded |
| `class="sentry-mask"` | Mask one specific element |
| `class="sentry-block"` | Do not record the element at all |
| `class="sentry-ignore"` | Record the element but not interactions with it |

Masking happens **in the browser, before anything is sent**. Turn masking off only for
elements you have deliberately reviewed.

## In the UI

**Replays** lists recorded sessions with user, duration, error count, browser and OS. Open
one for:

- **Playback** of the rrweb recording with a timeline
- **Visited pages** during the session
- **Errors** raised in that session, linked to their issues
- **Linked traces**, when tracing is on

From an issue, the **Replay** panel jumps straight to the moment the error happened. From
[user feedback](/en/products/user-feedback), a `replay_id` does the same.

## API

```text
GET /api/v1/projects/{project_id}/replays?stats_period=24h&limit=&offset=
GET /api/v1/projects/{project_id}/replays/{replay_id}
GET /api/v1/projects/{project_id}/replays/{replay_id}/events
```

## Cost

Replays are metered as the **Session Replay** service, per recorded session — the most
expensive unit in the price list. Sampling is your cost control; see
[Wallet](/en/billing/wallet).

## Troubleshooting

| Symptom | Cause / fix |
| --- | --- |
| No replays at all | `replayIntegration()` missing, or both sample rates are `0` |
| Replays but no error linkage | The error was captured in a different session/tab, or replay started after the error |
| Blank/broken playback | Cross-origin stylesheets can't be inlined — serve CSS from your own origin or allow CORS |
| Recording is huge | Long sessions on heavy DOMs; lower `replaysSessionSampleRate` and block noisy widgets with `sentry-block` |
| Sensitive data visible | Masking was turned off somewhere — audit `mask*` options and per-element classes |