A Bit Of Access

Alt or not, a browser extension / add-on for Twitter and Tweetdeck

Published by (updated )

Alt or not is a browser extension / add-on for Chrome, Firefox, and Edge. Easily see which images include alt text or not on Twitter (also supports GIF) and TweetDeck, and get a warning when posting images without alt text.

It's often difficult or cumbersome to tell if images have alternative text on Twitter or TweetDeck. Alternative (or alt) text is used to describe images for those who can't see the image, making them more accessible.

This extension shows which images are missing alternative text, and displays the alt text below the images when available.

The extension also warns users when images in a tweet have no alt text when tweeting, and you can choose to disable the button entirely when alt text is missing, requiring you to add descriptions before you can tweet.

Note: on TweetDeck descriptions are not displayed on GIFs, in the TweetDeck Preview descriptions do work on GIFs.

How does it work?

Install the extension on Chrome, Firefox, or Edge by downloading the correct version:

If needed, enable the extension, and you're done!

When updating from 0.6 or earlier to 0.7, you may have to re-enable the plugin for additional permission as it needs access to mobile.twitter.com as well.

To customize your experience you can change options by clicking the extension icon in your browser's toolbar, or through the extension manager of your browser.


A tweet with the image description below the image
An image description is displayed.
A tweet with the no alt label displayed on a GIF
No image description was available on this GIF.
The no alt label on the tweet button while an image without alt text is visible in the composer
An image description should be provided.
The options of the extension show every feature is optional
All features are optional.

Currently the extension has the following features (accurate for version 0.6 and above)

When reading tweets

  • Shows a red "No alt" label in the top left corner of images missing a description, this can be turned off
  • Displays the description of images below the images in the tweet, this can be hidden behind a button, or turned off entirely
  • Works on photos and animated GIFs for Twitter
  • Only works on photos where Tweetdeck includes the image descriptions (not on GIFs)
  • It should not impact the use of screen readers

When composing tweets

  • Shows hard to miss a red "No alt" label in the "send tweet" button when images lack alt text, this can be turned off
  • Choose to disable the tweet button entirely when images lack alt text
  • Show predefined description when a GIF is chosen from the GIF selector


Update: 0.9 (18-08-2021)

  • Predefined descriptions on GIFs from the GIF selector are now displayed below the GIF while composing tweets (might have a slight delay)
  • Alt Or Not now works correctly on all languages supported by Twitter (see languages currently supported)

Update: 0.8 (25-07-2021)

  • Fixed GIFs not getting checked while autoplay was enabled
  • Alt Or Not now supports the TweetDeck Preview
  • Added an experimental option to make scrollbars less intrusive, this is especially noticable on the TweetDeck Preview
  • Changed it so links in the settings page now open correctly in a new tab

Update: 0.7 (26-06-2021)

  • The extension now also runs on mobile.twitter.com
  • Relocated the creation of a button (optimization)

Update: 0.6 (19-05-2021)

  • Added options to customize the extension, all functions can be turn off individually
  • Added an option to disable the tweet button when images miss a description while writing a tweet
  • Added an optional light mode to the displayed alt text
  • Some visual changed to (groups of) alt text
  • Fixed unintentially flagging videos as images missing description while writing a tweet
  • Made sure all tweet buttons are synchronised when composing a thread
  • Code restructured and further optimized

Update: 0.5 (14-05-2021)

  • Added checking of alt text while writing tweets
  • A few small optimizations

Update: 0.4 (13-04-2021)

  • Improved the style on the displayed alt text for better readability

Update: 0.3 (27-02-2021)

  • Fixed an issue preventing alt text from displaying properly on some quote tweets on Twitter

Update: 0.2 (26-02-2021)

  • Prevented "null" appearing below YouTube previews on Tweetdeck
  • Fixed positioning of alt text on Twitter on tweets with multiple described images
  • Fixed positioning of alt text on Twitter on quote tweets with described images in the tweet and quoted tweet


The latest release (version 0.9) adds support for the full list of display languages that Twitter supports at the time of release. Please note that the language used by the extension itself remains English. The supported display languages are:

  • Arabic
  • Arabic Feminine
  • Bangla
  • Basque
  • Bulgarian
  • Catelan
  • Croatian
  • Czech
  • Danish
  • Dutch
  • Filipino
  • Finnish
  • French
  • Galician
  • German
  • Greek
  • Gujarati
  • Hebrew
  • Hindi
  • Hungarian
  • Indonesian
  • Irish
  • Italian
  • Japanese
  • Kannada
  • Korean
  • Malay
  • Marathi
  • Norwegian
  • Persian
  • Polish
  • Portuguese
  • Romanian
  • Russian
  • Serbian
  • Simplified Chinese
  • Slovak
  • Spanish
  • Swedish
  • Tamil

Can I see the source code?

Absolutely, you can take a look at the code whether you want to learn or check for potential issues with your own plugins. On that page the code is divided in segments with additional comments. Note: it is current up to date with version 0.7.

Questions or suggestions

If you have questions about, or suggestions for the extension, you can let me know on Twitter.

In case you are so inclined, you can buy me a coffee here to show your support. It's not needed, but always appreciated.