Selenium IDE Support for Firefox 55: Setup and Compatibility

Short answer: The legacy Selenium IDE does not work with Firefox 55 and later. Firefox 55’s move from the original XPI add-on format to WebExtensions broke the old extension, which Selenium had not updated. This warning applies to the legacy IDE extension, not to all Selenium automation in Firefox. For browser-based recording, install the rebuilt Selenium IDE from the Firefox add-on store. For code-driven browser automation, use Selenium WebDriver with geckodriver.

What changed in Firefox 55?

On August 9, 2017, Selenium contributor Simon Stewart announced that the legacy IDE would stop working starting with Firefox 55. Firefox was changing its extension technology from XPI to WebExtensions, and the Selenium project did not have the maintenance time needed to move the old IDE to the new system. The original IDE was also unmaintained.

The warning is specific: it does not mean Firefox 55 stopped working with Selenium WebDriver. WebDriver and the Selenium IDE browser extension are separate tools with separate compatibility requirements.

Install the rebuilt Selenium IDE in Firefox

Selenium later rebuilt the IDE as a browser extension. Selenium’s current documentation describes support for Firefox, Chrome, and Edge. Its documented Firefox setup is:

Install Selenium IDE from the Firefox add-on store. Find the Selenium IDE listing there and install it.
If its toolbar icon is missing, open about:addons and confirm Selenium IDE is enabled. If it is enabled but not visible, use Firefox’s toolbar customization to add or reveal the icon.
Launch Selenium IDE and create a new project. Give the project a name and enter the base URL of the application you intend to test.
Start recording, interact with the application in the browser, then return to the IDE and stop recording.
Save the project. Selenium documents the project as a single .side file.

The original 2018 announcement called the rebuilt IDE an alpha release at that time. That was a historical status, not a statement about its current release state. Check the live add-on listing and Selenium documentation for current availability and behavior; the documented flow does not guarantee compatibility with every Firefox build or every application.

Choose between Selenium IDE and WebDriver

Path	Best fit	Firefox compatibility detail	What to expect
Rebuilt Selenium IDE	Recording and replaying browser actions through a graphical interface	Install the current extension from the Firefox add-on store and check Selenium’s current documentation	Browser-based project workflow saved as a `.side` file
Selenium WebDriver with geckodriver	Code-driven browser automation	Mozilla’s table lists Firefox 55 as the minimum for geckodriver 0.19.0–0.20.1 with Selenium 3.5 or later; it says support is best in Firefox 57 and later	Requires a WebDriver client and driver setup; it is not the legacy IDE

Mozilla’s geckodriver compatibility table describes WebDriver support. It cannot be used to infer that the legacy IDE works in Firefox 55. If you need a graphical recorder, use the rebuilt IDE. If your tests need to be maintained as code or run in an automated pipeline, evaluate WebDriver and the matching driver versions for your environment.

Why not downgrade Firefox?

An older Firefox version may appear to offer a way to keep a legacy workflow, but Selenium’s notice warns that Firefox versions capable of running the old IDE are no longer supported. Downgrading is therefore not a routine fix: it leaves the project on an unsupported browser version. Prefer migrating the recording workflow to the rebuilt IDE or moving code-driven tests to WebDriver.

Troubleshooting

Symptom	Likely cause	What to do
The old IDE stopped launching after upgrading to Firefox 55 or later	The legacy extension is incompatible with Firefox’s WebExtensions transition	Install the rebuilt Selenium IDE from the Firefox add-on store, or use WebDriver if you need code-driven automation.
Selenium IDE does not appear in the toolbar	The extension may be disabled or its icon hidden	Check `about:addons`. If it is enabled, customize the Firefox toolbar and reveal the icon.
The recorded project does not use the expected starting address	The project base URL may be missing or incorrect	Edit the project’s base URL, then record the actions again from the intended application address.
A geckodriver compatibility table seems to say the old IDE should work	The table covers WebDriver and geckodriver, not the IDE extension	Choose the tool by workflow: rebuilt IDE for browser recording, WebDriver for code-driven automation. Match the driver and browser versions using Mozilla’s table.
A legacy project depends on an old Firefox release	The workflow relies on an unmaintained extension and an unsupported browser version	Plan a migration to the rebuilt IDE or WebDriver rather than treating an old browser as a supported long-term setup.

Or skip the browser setup

If your goal is to capture a page as an image or PDF rather than record browser interactions, ScreenshotNeo is a website screenshot API and MCP server. One GET request returns a screenshot or PDF. Its API options include device viewports, full-page capture, element selection, custom CSS and JavaScript, and PDF settings. See the ScreenshotNeo API documentation.

curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://stripe.com -o shot.webp

import requests

r = requests.get(
    "https://api.screenshotneo.com/v1/shot",
    params={"access_key": "YOUR_API_KEY", "url": "https://stripe.com"},
    timeout=90,
)
open("shot.webp", "wb").write(r.content)

const q = new URLSearchParams({ access_key: 'YOUR_API_KEY', url: 'https://stripe.com' });
const res = await fetch(`https://api.screenshotneo.com/v1/shot?${q}`);

ScreenshotNeo accepts consent banners like a visitor and removes more than 60 known consent platforms, newsletter popups, and chat widgets before capture; each cleanup step can be turned off. Bot checks, blank pages, timeouts, failed loads, and cache hits cost nothing, with response headers indicating the page verdict and billing status. Its MCP server gives AI agents tools for screenshots, page information, and PDF capture. The free plan includes 1,000 screenshots per month with no card; paid plans start at $5 for 3,000 screenshots. Sign up for 1,000 free screenshots a month, with no card required.

Performance, reliability, and cost considerations

Selenium IDE records browser interactions; WebDriver drives a browser through code; ScreenshotNeo returns a captured page as an image or PDF. They solve different tasks, so compare them by the output you need rather than treating screenshots as a replacement for browser tests.

Compatibility: Keep the browser extension, Firefox version, and WebDriver/geckodriver versions distinct in your setup notes. A working WebDriver pairing does not restore legacy IDE support.
Reliability: For recorded tests, verify that the project’s base URL and steps match the application flow. For WebDriver, use Mozilla’s compatibility information for the versions you run. Current extension behavior can change, so consult the live listing and docs.
Capture cost: ScreenshotNeo bills only clean shots; bot checks, blank pages, timeouts, failed loads, and cache hits are free. Choose a plan based on expected monthly volume: Free 1,000, Starter $5 for 3,000, Growth $15 for 15,000, Pro $39 for 60,000, Scale $99 for 250,000, or Business $249 for 1,000,000. Yearly billing gives two months free. Every feature is on every plan.

FAQ

Does Selenium IDE work with Firefox 55?

The legacy Selenium IDE does not. The rebuilt Selenium IDE is a separate extension with a separate installation path.

Does Firefox 55 support Selenium at all?

Firefox 55 support existed for certain historical geckodriver and Selenium WebDriver combinations. That does not make the legacy IDE compatible.

Is the rebuilt Selenium IDE still an alpha?

The alpha label was used in Selenium’s 2018 announcement. Check current Selenium documentation and the Firefox add-on listing for present status.

Can ScreenshotNeo record or replay Selenium tests?

No. ScreenshotNeo captures webpages as images or PDFs; Selenium IDE and WebDriver are for browser interaction and testing.