The Comidoc Extension, Explained by the Person Who Builds It

What it does on every Udemy page, every setting, and the community loop behind it. Chrome and Firefox, since 2019.

Published July 17, 2026

The Comidoc extension does one job: make sure you never pay for a Udemy course that has a verified coupon. It checks every course page you open, keeps the day's verified drops one click away, and puts any course under watch with a right-click. More than 10,000 people use it on Chrome and Firefox, in twelve languages, and its first version shipped in January 2019. This page is the complete tour, written by the developer who maintains it.

Comidoc extension banner: Verified Udemy Coupons, Always Working — Figure 1: The extension's promise, as stated on the Chrome Web Store

It watches Udemy pages so you don't have to

The core trick happens while you browse Udemy normally. Open any course page and the extension asks Comidoc whether a verified coupon exists for that exact course. If one does, you get a system notification on the spot; no tab switching, no searching a coupon site for the course you already found. And if there is no coupon today, a right-click on the page offers Add this course to my Comidoc watchlist: the alert system takes over and emails you the moment a verified code appears, even for courses Comidoc wasn't tracking yet.

Figure 2: The two moments that matter on a Udemy course page

Illustrative rendering; the menu wording is the real one.

The popup: today's verified drops, even offline

Click the toolbar icon and you get the latest verified coupons in three tabs: 100% off, discounted, and permanently free courses. The list is cached locally, so the popup opens instantly with the last snapshot even when you're offline, then refreshes in the background. The icon itself can carry a badge counting the new free courses since your last visit, so you know whether opening it is worth your time before you do.

Figure 3: The popup, faithful to the real layout

Illustrative rendering with placeholder counts; the real popup shows 30 courses per tab, or 100 with the extended setting.

Every setting, explained

The settings panel is six switches. Here is what each one actually does, and when you'd flip it:

Dark Mode. Exactly what it says; the popup follows it independently of your system theme.
Notification Popup. The Udemy-page check described above. Turn it off and the extension stops notifying while you browse Udemy; the toolbar popup keeps working.
Freebies Counter. The badge on the icon counting new free courses since your last check. Purely informational; off means a clean icon.
Include Practice Tests. Udemy hosts quiz-only courses with no video content. On by default; turn it off if you only want lecture courses in your list.
Include regular coupons issuers. The quality filter. Some instructors issue coupons constantly, five or more codes, as a marketing routine. Leave it on and you see everything (100 courses per tab); turn it off for a shorter list (30) that skips serial issuers.
Show Price. Price badges on course cards, so you see what the coupon saves before you click.

Figure 4: The settings panel, with the real labels

The community loop

The extension isn't just a reader; it's how the Comidoc database stays alive. When a user lands on a Udemy course with a coupon code Comidoc doesn't know yet, the code is submitted automatically, verified against Udemy, and shared with everyone. When a known coupon stops working, the same mechanism catches it and the listing is retired. It's a virtuous circle: every additional user makes the coupon list fresher for all of them. In a market where the median coupon dies in hours, that loop is the whole ballgame.

What it sends, and what it never touches

When you browse Udemy course pages, the extension sends only the URL of the page you are visiting to Comidoc's servers, to answer one question: is there a verified coupon for this course? Your Udemy account, your enrolled courses, your wishlist and anything else on the page are never read or transmitted. Signing in with your Comidoc account is optional; pairing unlocks your Premium benefits inside the extension, but everything above works without an account.

Seven years of the same extension

The first Comidoc extension shipped in January 2019 as a few hundred lines of jQuery. It was rebuilt in 2021, then rebuilt again on a modern stack that cut the package from 576 KB to 146 KB, and today runs at version 1.1.11 on Chrome and Firefox in twelve languages. Extensions in this niche appear and vanish with the coupon sites that spawn them; this one has outlived several generations of both, and its full history is part of the Comidoc story.

Install it in under a minute

Grab it from the Chrome Web Store or Firefox Add-ons, then browse Udemy as usual; the extension does the rest. If you want alerts and Premium benefits tied to your account, the pairing guide takes about thirty seconds. And if you mostly browse Comidoc rather than Udemy, the same superpowers live on the site: today's drops and per-course alerts.