Oobee (formerly known as Purple A11y) is a customisable, automated accessibility testing tool that allows software development teams to assess whether their products are user-friendly to persons with disabilities (PWDs).
This is the engine and command-line interface (CLI) for Oobee. The official application can only be downloaded at https://go.gov.sg/oobee-cli. We recommend that you download the software only from the official link, as other sources and/or third party links may pose risks and/or compromise your system.
For the user-friendly desktop application, check out Oobee.
If you wish to use Oobee as a NodeJS module that can be integrated with end-to-end testing frameworks, refer to the integration guide on how you can do so.
Portable Oobee is the recommended way to run Oobee as it reduces the difficulty for installation. Refer to Installation Guide for step-by-step instructions for portable Oobee.
Please ensure the following requirements are met:
- A Node distribution of 20 (LTS) or above.
- To check your version of Node, go into terminal and paste the command bellow
node -v- If you do not have node, or if there is a need to manage your node versions, you can consider using Node Version Manager (NVM). After NVM is installed, you can then install an LTS version of Node:
# Install NodeJS version with NVM
nvm install --lts
# For subsequent use, you will need to run the command below each time you open a new terminal
nvm use --lts- Install the required NPM packages with
npm install. - Build the project with
npm run buildbefore you try to run it withnpm start.
- A JRE/JDK distribution of version 11 or above.
- To check your version of Java, go into terminal and paste the command bellow
java --version- If you do not have java, you can consider installing Corretto distribution of OpenJDK.
- VeraPDF is used for scanning PDF files. Install VeraPDF by following the install guide. You may wish to use the Automated installation script provided on that page, and changing the XML installation script section
<installpath>/tmp/verapdf-test</installpath>to a location of your choice. - Ensure you have VeraPDF set in PATH then verify verapdf is installed correctly:
# Invoke the VeraPDF installer
# Windows users should use vera-install.bat instead of vera-install
./verapdf-install ./auto-install.xml
# Add VeraPDF to PATH. For subsequent use, you will need to run the command below each time you open a new terminal
export PATH="<location of verapdf>:$PATH"
# Verify verapdf is installed
verapdf --versionPlease refer to Troubleshooting section for more information.
Oobee can perform the following to scan the target URL.
- To run Oobee in terminal, run
npm start. Questions will be prompted to assist you in providing the right inputs. - Results will be compiled in JSON format, followed by generating a HTML report.
NOTE: For your initial scan, there may be some loading time required before use. Oobee will also ask for your name and email address and collect your app usage data to personalise your experience. Your information fully complies with GovTech’s Privacy Policy.
You may delete and edit your cached name and e-mail address by running the following command to delete
userData.txt:
- Windows (PowerShell):
rm "$env:APPDATA\Oobee\userData.txt"- MacOS (Terminal):
rm "$HOME/Library/Application Support/Oobee/userData.txt"
If userData.txt does not exists just run npm start.
You can interact via your arrow keys.
% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience.│
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan? (Use arrow keys)
❯ Sitemap
Website
CustomHeadless mode would allow you to run the scan in the background. If you would like to observe the scraping process, please enter n
% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience. │
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan? Sitemap
? Do you want oobee to run in the background? (Y/n) No% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience. │
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan? Sitemap
? Do you want oobee to run in the background? No
? Which screen size would you like to scan? (Use arrow keys) Desktop
? Please enter URL or file path to sitemap, or drag and drop a sitemap file here: https://www.sitemaps.org/sitemap.xml
Scanning website...
Fetching URLs. This might take some time...
Scanning website...
#oobee will then start scraping from the file link provided above.
#Console results
If the sitemap URL provided is invalid, an error message will be prompted for you to provide a valid input.
>> Invalid sitemap format. Please provide a URL with a valid sitemap.% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience. │
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan? Website
? Do you want oobee to run in the background? Yes
? Which screen size would you like to scan? (Use arrow keys) Desktop
? Please enter URL of website: https://www.domain.org
If the website URL provided is invalid, an error message will be prompted for you to provide a valid input.
>> Cannot resolve URL. Please provide a valid URL.% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience. │
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan? Website
? Do you want oobee to run in the background? No
? Which screen size would you like to scan? (Use arrow keys) (Use arrow keys)
❯ Desktop
Mobile
CustomChoose Mobile for a default mobile screen size scan and Custom to choose a device or specify viewport width options.
Custom flow allows you to specify a user journey by enabling you to click the scan button on each desired webpage on a browser to initiate scan. This is useful to scan websites that require user and form input.
- Start by choosing the
Custom flowin the menu selection.
% npm start
┌────────────────────────────────────────────────────────────┐
│ Oobee (ver ) │
│ We recommend using Chrome browser for the best experience. │
│ │
│ Welcome back User! │
│ (Refer to readme.txt on how to change your profile) │
└────────────────────────────────────────────────────────────┘
? What would you like to scan?
Sitemap
Website
❯ Custom- Specify the URL of the starting page you wish to scan
- A Chrome window will appear. Navigate through the pages and click on the Scan this page button at the top right of the broswer's page to conduct an accessibility scan on the current page.
- You may drag the top black bar to the bottom of the page in the event it prevents you from viewing / blocking certain page elements.
- Close the Chrome window to end the scan.
Other options:
- You can specify sites to exclude from accessibility scan (e.g. login page) by adding a pattern of the domain to
exclusions.txt. An example ofexclusions.txt:
\.*login.singpass.gov.sg\.*If the custom flow fails to start, you might be running multiple versions of Playwright. Re-install Playwright:
- On Windows, delete the folder
%USERPROFILE%\AppData\Local\ms-playwrightwhere%USERPROFILE%is typically located atC:\Users\<username>. - On MacOS, delete the folder
~/Library/Caches/ms-playwrightwhere~refers to/Users/<username>. - Within PowerShell (Windows) or Terminal (MacOS) app, run the following two commands to re-install Playwright:
npx [email protected] installCLI mode is designed to be run in continuous integration (CI) environment.
Run npm run cli for a set of command-line parameters available.
Usage: npm run cli -- -c <crawler> -d <device> -w <view
port> -u <url> OPTIONS
Options:
--help Show help [boolean]
-c, --scanner Type of scan, 1) sitemap, 2) website crawl,
3) custom flow, 4) intelligent
elligent
[required] [choices: "sitemap", "website", "custom", "intelligent"]
-u, --url Website URL you want to scan
[string] [required]
-d, --customDevice Device you want to scan [string]
-w, --viewportWidth Viewport width (in pixels) you want to scan
[number]
-o, --zip Zip filename to save results [string]
-p, --maxpages Maximum number of pages to scan (default: 1
00). Only available in website and sitemap
scans [number]
-f, --safeMode Disable dynamically clicking of page button
s and links to find links, which resolve is
sues on some websites. [yes / no]
[string] [default: "no"]
-h, --headless Run the scan in headless mode. [yes / no]
[string] [default: "yes"]
-b, --browserToRun Browser to run the scan on: 1) Chromium, 2)
Chrome, 3) Edge. Defaults to Chromium.
[choices: "chromium", "chrome", "edge"] [default: "chrome"]
-s, --strategy Crawls up to general (same parent) domains,
or only specific hostname. Defaults to "sa
me-domain".
[choices: "same-domain", "same-hostname"]
-e, --exportDirectory Preferred directory to store scan results.
Path is relative to your home directory.
[string]
-j, --customFlowLabel Give Custom Flow Scan a label for easier re
ference in the report [string]
-k, --nameEmail To personalise your experience, we will be
collecting your name, email address and app
usage data. Your information fully complie
s with GovTech’s Privacy Policy. Please pro
vide your name and email address in this fo
rmat "John Doe:[email protected]".
[string] [required]
-t, --specifiedMaxConcurrency Maximum number of pages to scan concurrentl
y. Use for sites with throttling. Defaults
to 25. [number]
-i, --fileTypes File types to include in the scan. Defaults
to html-only.
[string] [choices: "all", "pdf-only", "html-only"] [default: "html-only"]
-x, --blacklistedPatternsFilename Txt file that has a list of pattern of doma
ins to exclude from accessibility scan sepa
rated by new line
[string] [default: "exclusions.txt"]
-a, --additional Additional features to include in the repor
t:
screenshots - Include element screensho
ts in the generated report
none - Exclude
all additional features in the generated re
port
[string] [choices: "screenshots", "none"] [default: "screenshots"]
-q, --metadata Json string that contains additional scan m
etadata for telemetry purposes. Defaults to
"{}" [string] [default: "{}"]
-r, --followRobots Crawler adheres to robots.txt rules if it e
xists. [yes / no] [string] [default: "no"]
-m, --header The HTTP authentication header keys and the
ir respective values to enable crawler acce
ss to restricted resources. [string]
-y, --ruleset Specify scan ruleset for accessibility chec
ks
[string] [choices: "default", "disable-oobee", "enable-wcag-aaa", "disable-oob
ee,enable-wcag-aaa"] [default: "default"]
-g, --generateJsonFiles Generate two JSON files containing the
results of the accessibility scan:
1. `scanData.json`: Provides an overview of
the scan, including:
- WCAG compliance score
- Violated WCAG clauses
- Metadata (e.g., scan start and end times)
- Pages scanned and skipped
2. `scanItems.json`: Contains detailed
information about detected accessibility
issues, including:
- Severity levels
- Issue descriptions
- Related WCAG guidelines
- URL of the pages violated the WCAG clauses
Useful for in-depth analysis or integration
with external reporting tools.
[string] [choices: "yes", "no"] [default: "no"]
Examples:
To scan sitemap of website:', 'npm run cli -- -c [ 1 | sitemap ] -u <url_lin
k> [ -d <device> | -w <viewport_width> ]
To scan a website', 'npm run cli -- -c [ 2 | website ] -u <url_link> [ -d <d
evice> | -w <viewport_width> ]
To start a custom flow scan', 'npm run cli -- -c [ 3 | custom ] -u <url_link
> [ -d <device> | -w <viewport_width> ]
Click here for list of device options supported
- "Desktop" (defaults to a 1280x720 viewport)
- "Mobile" (defaults to iPhone 11 viewport)
- "Desktop Chrome HiDPI"
- "Desktop Edge HiDPI"
- "Desktop Firefox HiDPI"
- "Desktop Safari"
- "Desktop Chrome"
- "Desktop Edge"
- "Desktop Firefox"
- "Blackberry PlayBook"
- "Blackberry PlayBook landscape"
- "BlackBerry Z30"
- "BlackBerry Z30 landscape"
- "Galaxy Note 3"
- "Galaxy Note 3 landscape"
- "Galaxy Note II"
- "Galaxy Note II landscape"
- "Galaxy S III"
- "Galaxy S III landscape"
- "Galaxy S5"
- "Galaxy S5 landscape"
- "Galaxy S8"
- "Galaxy S8 landscape"
- "Galaxy S9+"
- "Galaxy S9+ landscape"
- "Galaxy Tab S4"
- "Galaxy Tab S4 landscape"
- "iPad (gen 6)"
- "iPad (gen 6) landscape"
- "iPad (gen 7)"
- "iPad (gen 7) landscape"
- "iPad Mini"
- "iPad Mini landscape"
- "iPad Pro 11"
- "iPad Pro 11 landscape"
- "iPhone 6"
- "iPhone 6 landscape"
- "iPhone 6 Plus"
- "iPhone 6 Plus landscape"
- "iPhone 7"
- "iPhone 7 landscape"
- "iPhone 7 Plus"
- "iPhone 7 Plus landscape"
- "iPhone 8"
- "iPhone 8 landscape"
- "iPhone 8 Plus"
- "iPhone 8 Plus landscape"
- "iPhone SE"
- "iPhone SE landscape"
- "iPhone X"
- "iPhone X landscape"
- "iPhone XR"
- "iPhone XR landscape"
- "iPhone 11"
- "iPhone 11 landscape"
- "iPhone 11 Pro"
- "iPhone 11 Pro landscape"
- "iPhone 11 Pro Max"
- "iPhone 11 Pro Max landscape"
- "iPhone 12"
- "iPhone 12 landscape"
- "iPhone 12 Pro"
- "iPhone 12 Pro landscape"
- "iPhone 12 Pro Max"
- "iPhone 12 Pro Max landscape"
- "iPhone 12 Mini"
- "iPhone 12 Mini landscape"
- "iPhone 13"
- "iPhone 13 landscape"
- "iPhone 13 Pro"
- "iPhone 13 Pro landscape"
- "iPhone 13 Pro Max"
- "iPhone 13 Pro Max landscape"
- "iPhone 13 Mini"
- "iPhone 13 Mini landscape"
- "Kindle Fire HDX"
- "Kindle Fire HDX landscape"
- "LG Optimus L70"
- "LG Optimus L70 landscape"
- "Microsoft Lumia 550"
- "Microsoft Lumia 550 landscape"
- "Microsoft Lumia 950"
- "Microsoft Lumia 950 landscape"
- "Nexus 10"
- "Nexus 10 landscape"
- "Nexus 4"
- "Nexus 4 landscape"
- "Nexus 5"
- "Nexus 5 landscape"
- "Nexus 5X"
- "Nexus 5X landscape"
- "Nexus 6"
- "Nexus 6 landscape"
- "Nexus 6P"
- "Nexus 6P landscape"
- "Nexus 7"
- "Nexus 7 landscape"
- "Nokia Lumia 520"
- "Nokia Lumia 520 landscape"
- "Nokia N9"
- "Nokia N9 landscape"
- "Pixel 2"
- "Pixel 2 landscape"
- "Pixel 2 XL"
- "Pixel 2 XL landscape"
- "Pixel 3"
- "Pixel 3 landscape"
- "Pixel 4"
- "Pixel 4 landscape"
- "Pixel 4a (5G)"
- "Pixel 4a (5G) landscape"
- "Pixel 5"
- "Pixel 5 landscape"
- "Moto G4"
- "Moto G4 landscape"
If the device name contains ( and ), wrap the device name in single quotes when entered into the CLI.
Please note that -d and -w are mutually exclusive. If none are specified, the default device used for the CLI scan is Desktop.
For example, to conduct a website scan to the URL "http://localhost:8000" and write to "oobee-scan-results.zip" with an 'iPad (gen 7) landscape' screen, run
npm run cli -- -c 2 -o oobee-scan-results.zip -u http://localhost:8000 -d 'iPad (gen 7) landscape'If the site you want to scan has a query string wrap the link in single quotes when entered into the CLI.
For example, to conduct a website scan to the URL "http://localhost:8000" and write to "oobee-scan-results.zip" with a custom screen width '360', run
npm run cli -- -c 2 -o oobee-scan-results.zip -u "http://localhost:8000" -w 360Once a scan of the site is completed.
A report will be downloaded into the current working directory.
Each Issue has its own severity "Must Fix" / "Good to Fix" based on the WCAG 2.2 Conformance.
For details on which accessibility scan results triggers a "Must Fix" / "Good to Fix" findings, you may refer to Scan Issue Details.
Please refer to the information below to assist in debugging. Most errors below are due to the switching between Node.js versions.
Issue: When your Node.js version is incompatible, you may face the following syntax error.
const URL_NO_COMMAS_REGEX = RegExp('https?://(www\\.)?[\\p{L}0-9][-\\p{L}0-9@:%._\\+~#=]{0,254}[\\p{L}0-9]\\.[a-z]{2,63}(:\\d{1,5})?(/[-\\p{L}0-9@:%_\\+.~#?&//=\\(\\)]*)?', 'giu'); // eslint-disable-line
^
SyntaxError: Invalid regular expression: /https?://(www\.)?[\p{L}0-9][-\p{L}0-9@:%\._\+~#=]{0,254}[\p{L}0-9]\.[a-z]{2,63}(:\d{1,5})?(/[-\p{L}0-9@:%_\+.~#?&//=\(\)]*)?/: Invalid escapeSolution: Install Node.js versions >= 20, i.e. Node.js v20 and above.
Issue: When you switch between different versions of Node.js in your environment, you may face the following error.
<user_path>/oobee/node_modules/bindings/bindings.js:91
throw e
^
Error: The module '<module_file_path>'
was compiled against a different Node.js version using
NODE_MODULE_VERSION 57. This version of Node.js requires
NODE_MODULE_VERSION 88. Please try re-compiling or re-installing
the module (for instance, using `npm rebuild` or `npm install`).Solution: As recommended in the error message, run npm rebuild or npm install
Issue: Not able to run Oobee due to the following error shown below
dyld: lazy symbol binding failed: Symbol not found: __ZN2v87Isolate37AdjustAmountOfExternalAllocatedMemoryEx
Referenced from: <user_path>/oobee/node_modules/libxmljs/build/Release/xmljs.node
Expected in: flat namespace
dyld: Symbol not found: __ZN2v87Isolate37AdjustAmountOfExternalAllocatedMemoryEx
Referenced from: <user_path>/PURPLE_A11y/oobee/node_modules/libxmljs/build/Release/xmljs.node
Expected in: flat namespace
zsh: abort node index.jsSolutions:
- Delete existing
node_modulesfolder and re-install the NPM packages withnpm install. - Refer to this GitHub issue for more alternative solutions
Limitation: Due to animations causing elements to shift out of the viewport after an Axe scan, there's a risk of element screenshots timing out within 5 seconds if the element is not found. This known issue is particularly prevalent in scenarios like carousels with interval-based transitions.
If you find a scan takes too long to complete due to large website, or there are too many pages in a sitemap to scan, you may choose to limit number of pages scanned.
To do this, run CLI mode npm run cli -- with the needed settings and specify -p 10 where 10 is the number of pages you wish to scan.
We recommend looking at our Technology Stack to understand the usage of each component. Take your time to understand.
Oobee uses third-party open-source tools that may be downloaded over the Internet during the installation process of Oobee. Users should be aware of the libraries used by examining package.json.
Oobee may send information to the website or URL where the user chooses to initiate a Oobee scan. Limited user information such as e-mail address, name, and basic analytics is collected for the purpose of knowing our usage patterns better.