Companies Using Backbone.js

Backbone.js is a library whose count says more about the software around it than about the people using it. Our October 2026 crawl finds it on 222,647 live domains, 131,037 of them matched to a company, which puts it 7th of 69 in JavaScript Frameworks with 3.08%. A domain counts when a page exposes the Backbone object, reports a version, or loads a script named like backbone.js. That test finds the library reliably. It can't tell you who chose it, and for Backbone.js that's the main question.

Where Backbone.js still runs

A site ends up with Backbone.js in 2026 in one of three ways. The biggest is a CMS copy. WordPress ships it in wp-includes, and Drupal core ships Backbone.js 1.6.1 as an internal library that its own library file marks for removal. WordPress is on 65.97% of live Backbone.js domains, and in a random sample of 72 sites we checked, 32 loaded the copy of Backbone that ships inside WordPress.

The second is a vendor template. BMO's US branch locator and Farmers Insurance's agent locator load the same Backbone.js 1.1.0 build from one asset server, llp-assets.meetsoci.com. Sign-in pages show the same pattern: UBS, Travelers, EDF and France Travail all load Backbone.js on the page where a customer logs in.

The third is an older build that still works. Siemens' Digital Exchange, rtx.com and Inter IKEA Group's site report version 1.4.0, released in February 2019. Walgreens' photo store reports 1.1.0, and Best Buy's country-selection page 1.1.2, from February 2014.

"A large share of the Backbone.js on the web today wasn't picked by the people who run the site. It came with WordPress, with Drupal, or with a locator or login page somebody else built." - David Thomson, CTO at TechnologyChecker.io

Sales Signal: split a Backbone.js list before you use it. WordPress domains on the 1.6 line are WordPress prospects, not JavaScript prospects. Domains reporting 1.4 or older on a custom app are the ones with a real front-end codebase to maintain.

What the version numbers say

Our rule reads Backbone.VERSION off the page, so we can date most installs. Of the 193,227 domains crawled between 11 September and 11 October 2026 that reported a version, 111,268 ran the 1.6 line, the one current WordPress and Drupal ship. 25,589 ran 1.4, first released in 2019. 23,174 ran 1.1, from 2013 and 2014, and 5,795 still ran 0.9, from 2012 and early 2013. In total 51,323 domains, about 26.6%, run release 1.3 or older, a Backbone.js release from April 2016 or earlier.

The usage line went from 180,672 in June to 222,647 in October, and I wouldn't read growth into it: the domains we crawl turn over every month, dead sites out and new ones in, and our detection widens. Since we began tracking Backbone.js on 16 March 2026, 35,699 domains have dropped it.

Sales Signal: the pre-1.4 group is the real maintenance market, 51,323 domains on a library release that's ten years old or more. Testing, security review and staged-migration services fit there. A pitch built on "Backbone is growing" doesn't.

Who the customers are

65.21% of matched companies with a known size have 1 to 10 employees and 21.5% have 11 to 50. Founding years lean to the 2010s (36.81%), with the 2000s at 18.44% and the 2020s at 16.38%. A company founded in the 2020s missed Backbone's early years entirely, so that last share fits a library that travels with a CMS. The enterprise tail is real but narrow: 490 companies above 10,000 staff, and at most of the ones we verified Backbone.js sits on a single property, such as Siemens' Digital Exchange, UBS's client sign-in or Walgreens' photo store.

Sales Signal: at large accounts, look for the team that owns that one property (e-commerce, customer login or the store locator) rather than the central web team.

Industry and geography

The industry chart is flat. Construction leads with 3.38%, then Real Estate (3.25%), Business Consulting and Services (2.87%), Advertising Services (2.68%) and Law Practice (2.59%). None of those is a software industry, which matches the WordPress overlap. By country, the United States has 43,992 matched companies, about four for every one of the United Kingdom's 11,195, and Germany (6,944), France (4,907) and Spain (4,871) together hold 16,722.

Sales Signal: for a WordPress agency or hosting pitch, filter Backbone.js domains by these industries and the 1.6 line. For front-end modernisation work, filter by version 1.4 or older and by companies above 200 staff.

React and Vue.js sit beside it

The usual question is what replaces Backbone.js. On our data, mostly nothing does, at least not cleanly. Of 40,014 domains we've seen running Backbone.js and React together, 30,386 still run both. Since March 2026, 2,037 domains dropped Backbone.js and run React, but 3,488 dropped React and kept Backbone.js. Vue.js runs the other way round: 1,519 domains dropped Backbone.js and run Vue.js, against 624 in the opposite direction, while 9,522 of 12,831 still run both. Angular (1,032 of 1,280 still running both) and Alpine.js (1,099 of 1,461) look the same. None of these pairs passes our switching tests.

"When a site adds React, Backbone.js usually stays. About three in four domains we've ever seen with both still run both, so a 'migrated off Backbone' list is mostly a list of sites that added something." - David Thomson, CTO at TechnologyChecker.io

Sales Signal: a team running Backbone.js beside React is mid-migration, and nothing in our data says that state ends quickly. Sell what makes the two coexist, such as shared state, routing and tests, before you sell a rewrite.

The stack around it

Underscore.js is on 96.6% of live Backbone.js domains, which follows from backbonejs.org listing it as the only hard dependency. Lodash is on 94.94% and jQuery on 92.97%, with jQuery Migrate on 63.28% and jQuery UI on 52.26%. That's an older front end. On the site layer, WordPress (65.97%) and Elementor (20.69%) lead, and Bootstrap (23.02%) turns up about four times as often as Tailwind CSS (5.91%). All shares are of the 223,300 live domains in our current crawl.

Sales Signal: anything you sell into this list has to work with jQuery and without a modern build step. A tool that assumes a bundler and ES modules will miss many of these sites.

What reviewers say

G2 reviewers praise Backbone.js for its lightweight design and flexibility and for keeping concerns separate, and they complain about the boilerplate code it takes. Our data fits both halves. The library is small, about 7.9 KB packed and gzipped for 1.6.0 according to backbonejs.org, so a CMS can ship it without most site owners noticing. And because each app writes its own glue code, upgrading takes work, which may be why 25,589 domains sit on 1.4 and 23,174 on 1.1.

Sales Signal: pitch upgrade or audit work on the cost of that glue code, not on the library's age.

Key takeaways

1. Backbone.js is on 222,647 live domains, 3.08% of JavaScript Frameworks and 7th of 69, but the count measures presence, not choice.
2. WordPress runs on 65.97% of those domains; 51,323 versioned domains run release 1.3 or older.
3. React and Vue.js get added beside Backbone.js more often than in its place.
4. Most big companies we verified run it on one property: a sign-in page, locator, investor site or storefront.

Sales applications

Outreach: "Your [property] still loads Backbone.js [version], a release from [year]. We help teams in that spot with [testing or a staged move] before anyone talks about a rewrite." Take the version from the page, never from a guess.

Targeting: on TechnologyChecker.io, filter Backbone.js domains to companies above 200 staff, then drop the WordPress sites. What's left is far more likely to be a custom app or a vendor template.

Competitive angle: domains running Backbone.js beside React or Vue.js are mid-migration. Offer help running the two side by side before you offer to finish the move.

The full list of 222,647 Backbone.js domains, with 131,037 matched company profiles, is on TechnologyChecker.io, filterable by size, country, industry and stack.