Readers/Reader Growth/Mobile Table of Contents
The mobile web experience with the default Minerva skin currently does not have a table of contents. This can make it more difficult for users to quickly and easily find the content they're looking for.
We conducted an A/B/C experiment in February 2026 to test adding a table of contents to see if it will improve the browsing and navigation experience. We found that the treatments both showed significant negative impact to retention. Based on our results, we do not recommend fully launching ToC as a feature in mobile web.
Background
[edit]Article sections are currently collapsed by default on mobile, which was intended to save users time in navigating as they scroll through long paragraphs of text. However, we suspect that this default may contribute to navigation difficulties since users must first open individual sections before reading.
In December 2025, we conducted an experiment on Arabic, Vietnamese, French, Chinese, and Indonesian wikis to 1) auto-expand all sections in an article by default and 2) pin the header of the section in the viewport to the top of the page.
We found that this change actually lowered the retention rate for readers by about 1.5% and shortened the amount of time they spent on wiki. We suspect that auto-opening all the sections on mobile ended up causing navigation difficulties by creating a wall of text, resulting in readers feeling overwhelmed or frustrated and leaving. So we decided to try out something different.
Now we want to see if offering a table of contents will improve those navigation needs. The new test will add a table of contents button on mobile. When users tap it, a panel slides up from the bottom showing the article’s section headings, which they can then click to jump to different parts of the page. Section headings will then also be auto-expanded when the table of contents is clicked.
We see this work as a part of addressing the decline in pageviews on Wikipedia. We want it to be easier to access content on the site, especially on mobile where newer readers tend to come in.
WMF’s Reader Foundational Research found that difficulty with in-article navigation, in particular on mobile, is a top complaint among readers.
We’re trying out a table of contents on mobile web to see if it supports ease of browsing based on data that it can be helpful for navigating. The Wikipedia Android app, for example, has a table of contents, which on average gets opened almost 4 times per user, much more often than users start a search, which is only an average of 1.5 times a session. The app also sees a 71.1% click-through rate, indicating strong usage on small screens.
Hypothesis
[edit]If we test adding a table of contents to Minerva mobile web, we will see at least one treatment show statistically significant improvement to logged-out reader retention.
Results
[edit]For our primary success metric, the treatments both showed significant negative impact to retention. We saw readers stay for longer sessions under both treatments, which we interpret to mean that readers spent longer looking for the information they wanted and were dissatisfied with the experience as a result, making them less likely to come back. We also saw fairly low open rates for the table of contents under both treatments, indicating that readers may have had a hard time finding it.
Our biggest takeaway so far: Readers get overwhelmed and have difficulty navigating long text blocks. The ToC buttons in our treatments did not improve wayfinding enough to mitigate the overwhelm observed in our prior Mobile Expanded Sections experiment, so we saw the same outcome of longer sessions due to more friction, resulting in lower retention. This result was the same across both treatments, even though Treatment 2 (the floating action button version of ToC) had a higher open rate and CTR.
A secondary takeaway is that, based on their respective open rates, the floating action button was more discoverable to readers than a button in sticky headers.
We have some theories to explore in the future for deeper understanding of these results:
- Scrolling feels more lightweight than tapping. TikTok and similar infinite scroll feeds may have conditioned consumers to scroll by habit before scanning for buttons to help with wayfinding. As a result, having to locate and tap a navigation button may now feel like adding cognitive load in the experience.
- Mobile web (i.e., casual) readers require new reading experience comparisonss. We had taken inspiration from the Kindle and Libby apps as comparisons, since both represent popular reading experiences and have tables of contents. We suspect that mobile web readers, who engage more casually with Wikipedia, may not want that type of long-form reading experience–or even the more immersive desktop or mobile apps reading experiences, and we thus need new comparison points for this audience.
Experimentation
[edit]
We will run an A/B/C test which tests a version of a mobile experience that:
- Adds a table of contents button on mobile
- Auto-expands section headings
- Makes it so when tapped a panel slides up from the bottom and shows article section headings
- Allows section headings to be clicked to jump to different parts of the page
The main metrics we will explore in this test are:
- Retention
- Open rate for the table of contents
- Click-through rate for section headings in the table of contents
Nice to have/secondary metrics include:
- Session length
The experiment will affect up to 10% of mobile users on Arabic, Chinese, French, Indonesian, and Vietnamese Wikipedias, and up to 1% of mobile users on English Wikipedia.
Experiment timeline
[edit]The experiment will go live the second half of February 2026 and will run for four weeks, when it will be turned off. We will then analyze results.
