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The annotation editor lets you draw on top of your screenshots to highlight important areas, point to specific UI elements, add step numbers, blur sensitive data, and more. It is built on Fabric.js and provides 14 specialized tools.

Opening the Annotation Editor

Click the Annotate button on any screenshot block that has an image. The annotation editor opens in a modal with your screenshot as the canvas background. When you finish, click Done to save your annotations or Cancel to discard changes.

Annotation Tools

The toolbar at the top of the annotation editor provides these tools:

Shape Tools

ToolShortcutDescription
ArrowADraw a straight arrow pointing from one spot to another. Great for indicating UI elements.
Curved ArrowShift+ADraw an arrow that follows a curved path. Useful for flowing callouts.
RectangleRDraw a rectangle outline or filled shape. Use to frame areas of interest.
OvalODraw an ellipse outline or filled shape. Use for circular highlights.
LineLDraw a straight line. Useful for underlines or connections.

Text Tool

ToolShortcutDescription
TextTClick on the canvas to place a text box. Type your label, callout, or instruction.

Drawing Tool

ToolShortcutDescription
FreehandDDraw freely with your mouse or trackpad. Perfect for circling or underlining informally.

Effect Tools

ToolShortcutDescription
HighlightHDraw a semi-transparent rectangle to highlight an area. Similar to a marker pen effect.
PixelatePBlur or pixelate an area to hide sensitive information (passwords, personal data, etc.).
SpotlightSDims the entire image except the selected area, drawing attention to a specific spot.
MagnifierMCreates a magnified zoom bubble over a small area, making tiny details visible.

Utility Tools

ToolShortcutDescription
Step CounterNPlaces numbered circles (1, 2, 3…) to indicate sequential steps. Numbers auto-increment.
CropCCrop the screenshot to a specific area, removing unnecessary edges.
EraserERemove individual annotation objects by clicking on them. Does not erase the background image.

Customization Options

Each annotation tool supports customization via the property panel:
PropertyAvailable forDescription
ColorAll toolsPick from 8 preset colors (red, orange, yellow, green, blue, purple, white, black) or choose a custom color
Stroke widthShapes, arrows, lines, freehandAdjust the line thickness (default: 2px)
OpacityAll toolsControl transparency from fully opaque to nearly invisible
Font sizeText toolAdjust the text size (default: 16px)
Font familyText toolText uses Inter font by default

Undo and Redo

The annotation editor has its own undo/redo history, separate from the main document editor:
ActionShortcut
UndoCmd+Z (macOS) / Ctrl+Z (Win)
RedoCmd+Shift+Z (macOS) / Ctrl+Shift+Z (Win)
You can also use the Undo and Redo buttons in the annotation toolbar.

Saving Annotations

1

Add your annotations

Use any combination of tools to annotate your screenshot.
2

Click Done

Press the Done button (checkmark) in the toolbar. The annotations are composited onto the image.
3

Composited image saved

The annotated image is saved as a new composited version to Backblaze B2. The original screenshot is preserved separately.
Annotations are composited (flattened) onto the image when you save. This means the annotated version is a new image file. The original un-annotated screenshot remains stored and can be restored.

Tips for Effective Annotations

1

Use arrows for direction

Point arrows at the exact button or field the reader needs to interact with. Keep arrows short and close to the target.
2

Use step counters for sequences

When a screenshot shows multiple actions, place numbered step counters (1, 2, 3) in the order the reader should follow.
3

Blur sensitive data

Always use the Pixelate tool to obscure passwords, API keys, email addresses, or other personal information before sharing.
4

Keep it minimal

Two or three annotations per screenshot is usually enough. Over-annotating can make the image confusing.
Once you click Done, annotations are composited onto the image. To change them, re-open the annotation editor — you will start with the composited image as a new base. For significant changes, consider replacing the screenshot and re-annotating.
Annotations are rendered at the same resolution as the original screenshot. The composited image maintains the original dimensions.
Yes. Any image uploaded to a screenshot block can be annotated, including photos, diagrams, and illustrations.
Yes. Since annotations are composited into the image file, they appear in PDF, HTML, Markdown, presentation, and AI video exports.
Undo reverses your last action (any tool). Eraser lets you click on specific annotation objects to remove them selectively, regardless of when they were added.