How to Use Fullstory to Find Drop-Off in a Checkout Funnel

The short answer: this works on FullstoryFree, because funnels are included on the Free plan and its 30,000 sessions a month with a year of retention cover the checkout of most mid-sized shops (plans page, funnels article, checked on 5 November 2026); install the snippet with capture off and Private by Default on, define one event per checkout step, build a funnel of three to five steps counted by unique sessions, read the step with the largest loss, split it by device, then connect Claude over Fullstory MCP so it lists the dropped sessions with replay links each week while a person watches them and picks the change.

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A checkout loses people in four or five places, and the analytics report gives one rate for the whole thing; the funnel splits the rate into steps and the replay shows the step. Plans, prices and rivals are in the Fullstory glossary entry.

Before you build it:

1. Check the free allowance against the month. Capture pauses at the limit rather than thinning out: for example, 1,500 sessions a day reaches 30,000 on day 20 (30,000 / 1,500 = 20), after which no new sessions are captured until the next cycle, and the warning email only goes out when usage is projected to pass 95% (session limit article). If your month is bigger, take the quote.
2. List the steps from what you have. The cart, shipping, payment and confirmation URLs and the button text on each: those become the events.
3. Write down the baseline. Orders per checkout session for the last four whole weeks from your own order system. Fullstory's median time to convert counts only people who completed each step (interpreting funnel data), so the number that proves the fix should come from the order system.

What you need

• A FullstoryFree account on a business email domain; Gmail-type addresses are refused and no card is needed (FullstoryFree article).
• Access to the page head, or the @fullstory/browser npm package, for the snippet under Settings, Data Capture and Privacy, Fullstory Setup (getting started).
• An Admin, Architect or Standard role to define events and save funnels; Explorers can build funnels but not save them (funnels article).
• A consent decision with counsel; the GDPR article says the DPA applies automatically and offers FS.consent() to hold capture until consent (GDPR article).

1. Install with capture off and masking on

Fullstory's checklist disables data capture before the snippet goes in, then installs; under Private by Default every element is masked, and you unmask what you need with element rules scoped to Preview Sessions Only until approved (privacy setup checklist). For a checkout, unmask product names and step headings, nothing typed.

2. Check it is capturing

In the browser's Network tab, the request to fs.js should return 200; a 202 means capture was blocked and the response carries a reason code (deployment check).

3. Define one event per step

Go to Settings, Data Management, Events, Create Event, or open a replay, enter Inspect Mode, click the element and choose Define event (define events article). Its example is the shape you want: clicked element "Add to Cart" when the Visited URL starts with /category-listing. Make four or five: cart viewed, shipping submitted, payment submitted, order confirmed. Each event takes up to 10 filters joined by OR, and defined events do not work with webhooks or Zapier.

4. Build the funnel

Name it, add the events in order with the event builder, and count unique sessions, since one buyer can start twice in a day; a funnel takes up to 20 steps in sequence, and if the first step shows zero users the article says to adjust it (funnels article). The Conversions tips recommend three to five steps covering a linear flow, and say to split a funnel in two where one gap is exceptionally large (Conversions tips).

5. Read the step that loses the most

The bar view gives the overall rate and each step's count; the trend view gives the rate per interval; Compare to past puts the previous period beside it (interpreting funnel data). Work on the step with the largest absolute loss, not the lowest percentage: 400 sessions lost at shipping matter more than 40 lost at payment.

6. Split it by device and by frustration

The interpreting article's example applies a Mobile segment to the funnel, and the tips say to narrow to desktop versus mobile when a signal only affects one group (interpreting funnel data, Conversions tips). Then build a segment from + Create, Segment, with the Rage Clicked event filter, as the quick start shows (segments quick start), and layer it on: a step that loses mobile rage-clickers is a layout fault, not a pricing one.

7. Let Claude pull the dropped sessions, and watch them yourself

Fullstory documents its MCP server for Claude: an Admin turns on StoryAI features under Settings, then in Claude you go to Customize, Connectors, Browse Connectors, search Fullstory and authorise; ask "What Fullstory tools are available?" and the tools should list (Claude setup guide). The vendor's page says MCP is available on every paid plan, so this step is paid (MCP page).

Each Monday, ask: "Run compute_funnel for the checkout funnel for the last 7 days against the 7 before, then use get_funnel_sessions to give me 10 sessions that dropped at the shipping step with their replay links." get_funnel_sessions returns replay URLs (tools reference). The human check is built into the limits: session tools return 10 by default with a hard cap of 50, tables stop at 50 rows, and anything the agent builds is a draft a person must save by hand (limits page). The agent lists; a person opens the ten replays and writes down what they saw.

8. Use Conversions if you have it

On Advanced and Enterprise, open Conversions, pick the funnel, the segment and a date range of 30 days or fewer, and Fullstory lists the signals correlated with completing or abandoning, with replays for each (Conversions guide, Conversions tips). Its tips say that opportunities are correlations and that elements with changing text will not show as opportunities.

Funnels are free because the funnel shows the hole and stops there; the view that ranks what made it, Conversions, sits two tiers up, and the agent that watches a funnel for drops needs StoryAI Premium on top (funnel drops article). The free plan is built to show the drop and sell the reason.

9. Change one thing and compare whole weeks

Ship the single fix for the worst step, wait for full weeks, and read the funnel with Compare to past and the order system beside it. Fullstory's tips note that correlation may not mean causation, and the only cure for that in a free account is one change at a time with a before-and-after on whole weeks, or a holdout if you can split traffic. Later, if you want that comparison run continuously rather than by hand, a causal attribution tool like Causality Engine does it. Disclosure: I founded it.

What Fullstory's documentation warns about

• A broad first step inflates the base; the tips say users can exit after any step, so the first one should be specific.
• A custom date range over 30 days is refused in Conversions, and fewer than 100 users at the final step makes confident correlations unlikely.
• Funnels made only of custom events show no page performance opportunities unless a Visited URL step is included.

FAQ

Do I need a paid plan to build the funnel?

No. Funnels are on Enterprise, Advanced, Business and Free (funnels article). Conversions and MCP are paid, and Funnel Drops monitoring needs StoryAI Premium.

Why did capture stop in the middle of the month?

The session or server-event allowance ran out; Fullstory pauses capture until the cycle resets and shows usage under Settings, Account Management, Subscription (session limit article). Existing sessions stay viewable.

What does Claude see when it queries Fullstory?

Only the org the server is scoped to, and never a saved change: the MCP creates drafts, returns at most 50 sessions and 50 table rows, and does no user management or settings changes (limits page).