Every modal in our app shared one URL. Our analytics couldn't tell them apart.

Our product runs a lot of its life inside modals. Open a payment, reconcile a deposit, add a bank account, half the real work happens in a dialog that pops over the page. And every single one of those modals lived at the same URL as the page behind it.

Which meant our analytics were blind to all of it. Every modal open looked like the user just sitting on the dashboard. We had a busy, important part of the product that, as far as our data was concerned, didn't exist.

Give the modal a URL

The fix sounds trivial. Give every modal its own URL. Open the transfer modal, the address bar gets a little tag saying which modal is open. Now the modal is a thing you can point at, filter on, build a funnel from. A dialog that used to be invisible becomes a first-class, measurable surface.

Simple idea. The gotchas are where it got interesting, and where I'd save you some time.

The gotchas nobody warns you about

The first one nearly fooled me completely. We added the URL tags, opened a modal, and no pageview fired. The analytics library treats a change to that little tag as "same page, nothing happened," so opening a modal recorded nothing at all. The whole scheme looked broken. It wasn't broken, it just needed us to tell the library that yes, this counts as a view. If you do this and see zero events, that's almost certainly what's happening. Don't panic, don't rip it out.

The second one was quieter and nastier. The tags started stacking. Open one modal, then another, and instead of replacing the first tag the URL kept both, then three, then a growing pile. So a funnel built on those URLs would show people entering step one and then apparently vanishing, because by step two the URL was some compound thing that matched nothing. A clean-looking chart showing catastrophic drop-off, and it was a measurement bug, not a user problem. That's the sort of thing that gets a real feature killed in a review by someone who trusts the chart.

There were smaller ones too. A modal whose tag didn't match its name, so you'd filter for the thing and get nothing. Tags that were written to the URL but never read back, so you couldn't deep-link to a modal or reload into it. Each individually minor, each capable of quietly lying to you.

The one line I'd tattoo on this: if you can't address it with a URL, you can't measure it, and you can't link to it. Modals, wizard steps, side panels, anything that changes what the user is looking at deserves its own address. It makes the invisible parts of your product measurable and shareable.

Just go in knowing the tooling was mostly built for pages that fully reload, and modals aren't that. Confirm your pageview actually fires. Make the tag replace, not stack. And treat any funnel that shows a perfect cliff with suspicion, because the most confident-looking chart is often the one measuring your instrumentation instead of your users.

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Part of a series on building an AI collaborator for our design team at Xflow. Each post stands on its own.