Google Apps Accessibility Guide


While Google Docs, Slides, and Sheets do not feature a native built-in accessibility checker, the University of Illinois provides Grackle Suite to all faculty, staff, and students to identify and resolve accessibility barriers directly within Google Workspace.

Note: You no longer need to export Google files to Microsoft Office format to perform accessibility checks. Grackle runs directly inside Google Docs, Sheets, and Slides.

What is Grackle?

Grackle is an automated accessibility checking add-on for Google Workspace. It scans documents for common accessibility barriers and provides guided prompts to fix them directly within your document. Examples of these barriers include missing alt text, low color contrast, improperly nested headings, and untagged table headers.

How to Access Grackle at Illinois

Grackle has been automatically installed for all active Illinois Google Apps accounts.

Opening Grackle in Google Workspace:
  1. Open your document in Google Docs, Sheets, or Slides.
  2. In the top menu bar, click Extensions.
  3. Hover over Grackle Docs, Grackle Sheets, or Grackle Slides, and click Launch.
  4. A side panel will open on the right displaying the real-time accessibility check.
Troubleshooting: Don't see Grackle under Extensions?
  • Check active account: Ensure you are logged into your official Illinois Google Apps account using your @illinois.edu email address.
  • Check file format: Ensure you are editing an actual Google Workspace file, not a preview of an uploaded Microsoft Office file.
  • Manual Installation: If missing, navigate to Extensions > Add-ons > Get add-ons, search for Grackle Docs (or Slides/Sheets), and install it manually.

Grackle Status Indicators

When you launch Grackle, the sidebar evaluates your document against WCAG standards using three status icons:

  • Green Checkmark: Passed automated test.
  • Checkmark with Exclamation Badge: Passed with warning / skipped warning (requires manual review or action).
  • Red X: Failed automated test (action required).

Fixing Common Accessibility Errors with Grackle

Click on an application below to view detailed instructions for resolving specific error flags.

Google Docs: Step-by-Step Error Resolution
Document Settings & Language
  • Document title is required: Open Grackle Docs, select Document title is required, and select Edit or check Use the Google Doc name.
  • Document language should be specified: Select File > Language from the top Google menu and select your primary language.
Images, Drawings, & Equations
  • Images & Drawings should have alt text: Select the flagged visual, click Image Options in the toolbar, select Alt Text, and type your description.
  • Equations should be described: Select Equations should be described in Grackle, click TAG, and enter alt text describing the mathematical expression.
Headings & Structure
  • A single "Heading 1" should be used: Ensure your main document title uses Heading 1 style and that no other text uses Heading 1.
  • Headings must be properly nested: Do not skip heading levels (e.g., jump from Heading 1 to Heading 3). Select the text, open the Styles dropdown in the toolbar, and assign the proper heading rank.
Tables & Lists
  • Tables must be tagged: Click TAG next to the table error in Grackle. In the pop-up, designate header rows/columns, or mark it as a layout table.
  • Avoid merged and empty cells: Remove merged cells to preserve standard reading order and fill or delete empty cells.
  • Tagging Lists: Ensure bulleted and numbered items use the official toolbar list controls (not typed dashes or numbers).
Content & Typography
  • High color contrast: Ensure small text has at least a 4.5:1 contrast ratio against the background (3:1 for large text).
  • Font sizing & alignment: Use easy-to-read sans-serif fonts at 12pt+, maintain left-alignment for body text, and avoid ALL-CAPS styling.
Google Slides: Step-by-Step Error Resolution
Presentation & Slide Setup
  • Presentation title required: Open Grackle Slides, select Presentation title is required, and select Edit Title.
  • A slide should have a title: Right-click the flagged slide, select Apply Layout, and choose a layout containing a designated Title placeholder (e.g., "Title and Content").
  • Slide titles should be unique: Give every slide a distinct title so screen reader users can navigate effectively.
  • Avoid empty slides: Delete placeholder or unused blank slides from the presentation layout.
Visual Elements & Alt Text
  • Images & Elements alt text: Click the flagged graphic or shape, open Image Options > Alt Text, and enter a clear description in the Description box.
  • Remove empty text boxes: Delete unused, blank text containers from slide canvases.
  • Recombine broken lists: Ensure multi-line bullet lists are formed in a single text box using Google Slides' native list toolbar controls.
Tables in Slides
  • Tag and describe tables: Because Google Slides lacks native table header controls, open Grackle Slides, click TAG next to the table error, and designate row/column headers in the Grackle panel.
  • Avoid merged/empty cells: Ensure data grid structure remains uniform without merged regions or blank data cells.
Formatting & Trailing Lines
  • Font size for slides: Use easy-to-read sans-serif fonts sized to at least 24pt (28pt+ recommended).
  • In-line style changes (+TAG): If styling (bold, color, italics) carries critical meaning, select the error in Grackle, click +TAG, and add a descriptive label.
  • Remove empty trailing lines: Select Empty trailing lines could be removed in Grackle, click Paragraph, and backspace extra empty lines out of the flagged text box.
Google Sheets: Step-by-Step Error Resolution
Workbook & Sheet Structure
  • Document title: Click the title box at the top left of your Google Sheet to give the overall workbook a descriptive name.
  • Descriptive sheet names: Right-click individual worksheet tabs at the bottom, select Rename, and replace default names like "Sheet1" with contextual labels.
  • Manage workbook size: Keep individual tabs under 50 sheets and avoid creating excessively oversized data grids on a single sheet tab.
  • Remove empty sheets: Delete unused or blank worksheet tabs.
Tables & Data Alignment
  • Adding headers via Freeze: Highlight your header row/column, go to View > Freeze, and select the row or column to programmatically designate headers.
  • Using Table features: Go to Insert > Tables to convert raw ranges into structured tables with pre-built accessible headers.
  • Table placement & structure: Maintain one primary data table per sheet tab, avoid merging cells, and eliminate isolated floating cells detached from primary data ranges.
Charts & Visual Formatting
  • Chart Alternative Text: Select your chart, click the three vertical dots in the upper right corner, select Alt Text, and enter a summary description of the data trend.
  • Contrast & Typography: Ensure background fill colors and cell text pass WCAG AA contrast tests (minimum 4.5:1 ratio) and maintain 12pt+ font sizes.