Session Replay
Session Replay that captures the right sessions - and nothing it shouldn't
The two most common Session Replay surprises are opposites: teams that capture nothing (the sample rate defaults to zero) and teams that capture too much (masking left at defaults nobody chose). Both are configuration, and both are documented.
How do you enable it?
Two supported shapes, per the docs: a plugin on the Amplitude Analytics SDK you already run, or a standalone SDK - on Browser, iOS, Android, and React Native, with Google Tag Manager, Segment, and RudderStack paths for third-party stacks. On the web the plugin route is two lines: add @amplitude/plugin-session-replay-browser and register it with amplitude.add(sessionReplayPlugin()) before init.
- Install the plugin alongside your existing Browser SDK - replay then rides the identity and session context you already have.
- Set sampleRate deliberately: it is a 0-1 value and the default is 0 - no sessions are captured until you choose a rate. Amplitude also supports Remote Configuration of settings including the sample rate, so you can tune without redeploying.
- Note the fail-safe: if remote configuration is enabled but fails to load, Session Replay captures nothing - a conservative default worth knowing before you debug 'missing' replays.
What gets masked, and who decided?
Amplitude masks all text input fields by default, and privacyConfig.defaultMaskLevel sets the overall posture - the default is Medium:
| Mask level | What the docs say it does |
|---|---|
| Light | Masks only a subset of sensitive inputs - passwords, credit card numbers, telephone numbers, email addresses |
| Medium (default) | Masks all form fields and text inputs; other on-page text is captured as-is |
| Conservative | Masks all text and all form fields - HTML text, user input, and links |
Fine-grained control: .amp-mask / .amp-unmask / .amp-block CSS classes and maskSelector/unmaskSelector/blockSelector options. Choose the level with your privacy counsel, not by inertia - 'Medium' still captures non-form page text.
How much replay does your plan include - and how do you spend it well?
Per amplitude.com/pricing at the time of writing: Free includes 10K monthly session replays, Growth 20K, Enterprise 50K. The Plus tier's replay volume is not shown on the public pricing page - confirm with Amplitude rather than assuming. Pick your sampleRate from these quotas and your traffic, not from optimism: quota exhausted mid-month means the session you needed wasn't captured.
Better than a blunt rate: Targeted Replay Capture focuses the quota on sessions matching criteria you define - specific events (Checkout Started), event or user properties (plan = Pro), page URLs (/checkout), combinable with OR logic. Each condition gets its own sample rate, and the settings UI estimates how much quota a condition will use based on historical traffic. Amplitude's own guidance draws the line cleanly: use targeted capture to observe specific behaviors or high-value segments; use the global sample rate when you only need broad coverage. For most teams the funnel's leaking step is exactly such a criterion - which is why this feature quietly changes the replay ROI math.
The workflow that makes replay worth its quota
Replay pays off as a drill-down, not a channel. The documented path: from a chart data point, open Microscope and choose Watch Session Replays (or View User Streams filtered to streams with replays, then Play Session) - supported on Event Segmentation, Funnel Analysis, Journeys, Experiment, and User Sessions charts. The docs note this chart-level entry requires Growth or Enterprise with the replay add-on.
That wiring is the whole game: the funnel tells you 38% abandon at payment; the replay attached to that exact data point shows you the hesitation. Teams that browse replays like television get privacy risk and no insight; teams that jump from an anomalous chart to five matching sessions get answers in minutes. (That usage judgment is ours; the mechanics above are documented.)
In practice: We wire replay into your event taxonomy so any chart can answer 'show me one' - part of the AI-enablement sprint.
Sources
- Amplitude docs: Session Replay overview (SDKs, platforms)
- Amplitude docs: Session Replay browser plugin (setup, sampleRate)
- Amplitude docs: Session Replay privacy settings (mask levels)
- Amplitude docs: Targeted Replay Capture (criteria-based quota targeting)
- Amplitude docs: Microscope (replays from charts)
- Amplitude pricing (replay quotas by plan)
Product capabilities change - every claim above links to the primary source it came from. Judgment calls and field observations are ours and labeled in-line.
Frequently asked questions
Why is Amplitude Session Replay not capturing any sessions?+
Check sampleRate first: it is 0 by default, so a fresh install captures nothing until you set a value between 0 and 1. Second check: if you enabled remote configuration and it fails to load, the documented fail-safe is to capture no sessions at all.
Does Amplitude Session Replay mask passwords and card numbers?+
Yes - text input fields are masked by default, and even the lightest documented mask level covers passwords, credit card numbers, phone numbers, and email addresses. The default overall level is Medium (all form fields and text inputs masked). What Medium does NOT mask is regular on-page text, so review the level against your content with counsel.
Can I open a session replay directly from a funnel?+
Yes: Microscope on a chart data point offers Watch Session Replays, supported on Funnel Analysis among other chart types - per the docs this chart-level entry point requires a Growth or Enterprise plan with the Session Replay add-on.
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