Getting Started with RUM & Session Replay

Overview

This guide introduces AppStatus RUM & Session Replay and covers:

• One browser snippet, no build step required
• Core Web Vitals from real visitors, not a lab
• Breakdown by page, browser, device and country
• JavaScript errors correlated with backend traces
• Masked session replay for the sessions that went wrong

What is RUM & Session Replay in AppStatus?

RUM measures what your visitors actually experienced — how long the page took to become usable, how quickly it responded to their first interaction, and how much the layout moved under them while it loaded.

Sessions can be replayed to see the exact path a user took into a failure. Text and input values are masked structurally in the browser before the recording is uploaded, so the content of forms never leaves the visitor’s device.

Key capabilities:

• Core Web Vitals — load, interaction delay and layout shift — per page
• Segmentation by country, device, browser and connection
• Frontend JavaScript errors linked to the backend trace they triggered
• Session replay with structural masking applied before upload
• Recordings retained for 14 days, with on-request deletion

What you will see

What the page performance table looks like

Scroll the table sideways to see every column.

Troubleshooting

Operational Guidance

• Segment by country and device before concluding the site is slow — the average hides the worst region.
• A frontend error with no matching backend error is usually a client-side or CDN problem.
• Use replay to answer "what did they click", not as a general debugging tool; it is slower to read than a trace.
• Recordings can be deleted on request; deletion applies immediately.

Step-by-Step Setup

RUM is the fastest thing on this list to switch on: one snippet in your page template. Everything after that is deciding how much to sample and confirming masking behaves on your own forms.

1. 1

   Create an ingest key scoped to RUM

   Open Ingest Keys and create a key scoped to RUM for the environment you are setting up. The key value is shown once — copy it into your secret manager now, not into source control.

   WhereIngest Keys → Create key

   Tip

   One scope per key. A key reused across signals turns a single leak into full ingest access.

2. 2

   Add the browser snippet

   Paste the snippet into your base template, as early in the head as you can and before other scripts. It loads asynchronously and does not block rendering.

   WhereRUM → Add application → copy snippet

   Tip

   The RUM key ships in your page source. That is by design — its scope lets it send browser telemetry and nothing else.

3. 3

   Choose sample rates

   Set the metrics sample rate high so your Web Vitals are representative, and the replay sample rate low. Replay is far heavier than metrics and you rarely need every session.

   WhereRUM → Settings
4. 4

   Verify masking on a real form

   Load a page with a login or checkout form, then open its replay. Confirm the input values are masked. Masking is applied in the browser before upload, but custom components can need an explicit mask attribute.

   WhereRUM → Sessions → open a replay

   Tip

   Do this before rolling out widely, and again after any significant frontend change.

5. 5

   Segment before drawing conclusions

   Open the page table and break the numbers down by country and device. A site that looks fine on average is often poor for one region or one device class.

   WhereRUM → Pages

Configuration Options

Every option you can set, what each choice means, and what to pick. Use this as a reference while you fill in the form.

Feature Reference

Every feature, where to find it in the app, and what it does. Use this when you know what you want to do but not where it lives.

Next Steps

Continue building your monitoring stack: