Private Browser-Based Image Labeling

Free Online Image Annotation Tool with Local Processing

Create bounding boxes and polygon segmentation labels directly in your browser, with keyboard shortcuts, a label picker after every shape, and drag-and-drop folders. PixLab Annotate processes source images locally on your device, with no image transfer to PixLab servers, and exports structured JSON for machine learning datasets.

Local Processing
No Image Transfer
Structured JSON Export
No Account Required
Keyboard Shortcuts
Autosave
Start Labeling Locally View Features
PixLab Annotate image labeling interface with bounding box and polygon tools

Image annotation without server uploads

Zero

Source-Image Transfers

Images remain on your device

Browser

Local Processing

No annotation server required

JSON

Structured Export

Coordinates and label metadata

No Account

Start Immediately

Open the browser tool and label

Core Features

Online Image Annotation Features for ML Datasets

Drop a folder of images, draw bounding boxes or polygons, label each shape as you draw it, track which images are done, and export structured JSON from one browser workspace.

Multiple-Image Annotation

Drop images or whole folders onto the page, then move through them with the arrow keys. Mark each image as done and jump straight to the next one still to label. Source files remain on your device throughout the session.

Drag & Drop Folders Arrow-Key Navigation Done Tracking
dataset_folder_1
20 Images
Dataset sample: autonomous driving scene 1
Dataset sample: autonomous driving scene 2
Dataset sample: autonomous driving scene 3
Dataset sample: autonomous driving scene 4
Dataset sample: autonomous driving scene 5
Dataset sample: autonomous driving scene 6

Bounding Boxes and Polygons

Draw rectangular bounding boxes for object detection or polygon outlines for segmentation datasets. Select, move and reshape any shape right on the canvas, with zoom and pan for detailed labeling.

Object
Mask

Structured JSON Export

Export machine-readable JSON with annotation coordinates, rectangle geometry, and label metadata for use in your data preparation or model training pipeline.

{"content": [...]} {"labels": {...}}

Autosave, Undo and Redo

Annotations are saved in your browser as you work. Undo or redo any change, even after a reload, and continue later in the same browser on the same device.

Saved in browser storage Ctrl+Z

Keyboard Shortcuts for Every Step

Switch tools, assign labels, undo, delete, zoom and change image without leaving the keyboard. Press ? in the app, or click the keyboard icon in the toolbar, to see the full list.

Built-in Shortcut List Mac & Windows
  • Select, rectangle, polygon VRP
  • Assign label 1 to 9 19
  • Undo / redo Ctrl+ZCtrl+Shift+Z
  • Previous / next image ←→

Label Picker After Each Shape

A small picker opens next to every new shape. Press Enter to keep the label, a number key to pick another, or type a new name to create a label with its own color.

car person

Ready to label images without transferring them to a server?

Open the Annotation Tool
PixLab Annotate

Free Online Image

Annotation Tool

Annotate images for object detection and segmentation directly in your browser. Compare an unlabeled source image with its bounding box and polygon annotations below.

Unlabeled source image before annotation in PixLab Annotate Labeled image showing bounding boxes and segmented regions in PixLab Annotate

Open the app, select or drop images from your device, and start labeling without an account. Source images are processed in your browser and are not transferred to PixLab servers.

Open Annotate
Bulk folder labeling workflow in PixLab Annotate
Multiple-Image Workflow

Batch Image Annotation Without Cloud Uploads

Drop a folder of images onto the page, or pick files, then move through them with the arrow keys. The browser handles the working set on your device, so source images do not need to be sent to a remote annotation service.

  • Drag-and-drop folders: Drop images or whole folders anywhere on the page. Images load in natural order (img2 before img10) and other files are skipped.
  • Arrow-key navigation: Move across the images with the left and right arrow keys or the on-screen arrows.
  • Progress tracking: Mark images as done, see how many are left, and jump to the next image still to label.
  • On-device workflow: Keep source images on your device while you annotate them in the browser.
Label an Image Batch
Object Detection and Segmentation

Bounding Box and Polygon Annotation Tools

Use rectangles to mark object locations and polygons to trace irregular boundaries for segmentation. Select any shape to move or reshape it right on the canvas, while zoom, pan, full-screen display, and snapshots support closer inspection.

  • Polygon segmentation: Place vertices around irregular object boundaries, then finish with Enter, a double-click or a click on the first point.
  • Bounding boxes: Draw rectangular regions for object detection datasets, one after another, even inside other boxes.
  • On-canvas editing: Click a shape to select it, drag it to move it, drag a polygon edge to add a point, and double-click a point to remove it.
  • Canvas controls: Zoom with the mouse wheel or the + and − keys, fit the image with 0, pan with Space and drag, and capture snapshots.
Try the Annotation Tools
Bounding box and polygon segmentation tools in PixLab Annotate
No Data Transfer

In-Browser Image Processing by Design

PixLab Annotate loads and processes source images inside your browser. The images are not uploaded to PixLab servers, making the tool useful when a cloud annotation workflow is unnecessary or unsuitable for the dataset.

  • No source-image transfer: Selected images remain on your device during annotation.
  • Browser-based storage: Annotation state, class names, and colors are kept in your browser storage.
  • Autosave with undo and redo: Every change is saved in your browser as you work, and can be undone with Ctrl+Z or redone with Ctrl+Shift+Z.
Start in Your Browser
Annotation history and class management panel in PixLab Annotate
export_data.json
Output File 
[{
  "content": [
    { "x": 1368.42, "y": 1236.29 },
    { "x": 3036.72, "y": 1236.29 },
    { "x": 3036.72, "y": 2394.45 },
    { "x": 1368.42, "y": 2394.45 }
  ],
  "rectMask": {
    "xMin": 1368.42,
    "yMin": 1236.29,
    "width": 1668.30,
    "height": 1158.16
  },
  "labels": {
    "labelName": "meat",
    "labelColor": "#ff0000",
    "labelColorRGB": "255,0,0",
    "visibility": true
  }
}]
Structured JSON Export

Machine-Readable Annotation Data

Export annotations as structured JSON that your own scripts can read, validate, transform, or map into the schema required by a computer vision training pipeline.

  • Annotation geometry: Export point coordinates and rectangle mask dimensions for each labeled object.
  • Label metadata: Preserve class names, colors, RGB values, and visibility settings.
  • File-based workflow: Save the JSON locally and adapt it to the format expected by your training code.
Create JSON Annotations
Keyboard-First Workflow

Label Faster with Keyboard Shortcuts

Every common action has a key, so you can draw, label, review and move to the next image without reaching for the toolbar. Press ? in the app, or click the keyboard icon in the left toolbar, to open the full shortcut list at any time.

  • Label picker after each shape: Press Enter to keep the highlighted label, 1 to 9 to pick another, or type a new name to create a label with a distinct color.
  • Edit without the mouse: Delete removes the selected shape, Backspace removes the last polygon point, and E changes the selected shape's label.
  • Review a whole batch: D marks the image as done, N jumps to the next image to do, and Ctrl+S saves the JSON.
Try the Shortcuts
Keyboard shortcuts
Press ?
Select, rectangle, polygon
VRP
Assign label 1 to 9
19
Change label, delete shape
EDelete
Undo, redo
Ctrl+ZCtrl+Shift+Z
Finish polygon, remove last point
EnterBackspace
Previous, next image
←→
Mark done, next to do
DN
Zoom in, out, fit
+−0
Pan the image
Space + drag
Save JSON
Ctrl+S
Who It's For

Who Annotate Is Built For

PixLab Annotate is a practical fit for developers, researchers, and teams that need manual image labeling without sending source datasets to a cloud annotation platform.

ML Engineers

Create bounding box and polygon labels for experiments, baselines, and model iteration without installing an annotation server.

Dataset Preparation

Define clear class names with distinct colors, mark each image as done as you go, and export consistent JSON annotation data for downstream processing.

Research Labs

Prepare and review image datasets in the browser while keeping source files on lab machines.

Startups and Small Teams

Test a label taxonomy and prepare early datasets without accounts, server setup, or a cloud workspace.

QA and Review Passes

Select, move and reshape shapes, undo or redo any change, and toggle label visibility to inspect and correct annotations before export.

Classroom and Training Use

Teach bounding boxes, polygon segmentation, class labels, and JSON annotation structure with a tool students can open in a browser.

Launch Annotate
FAQ

PixLab Annotate
Frequently Asked Questions

Details about in-browser image processing, supported annotation tools, keyboard shortcuts, browser storage, and JSON export.

Open Annotate
What is PixLab Annotate?
PixLab Annotate ↗ is a free online, browser-based image labeling tool for creating bounding boxes and polygon segmentation labels. It includes a quick label picker, keyboard shortcuts, drag-and-drop folder loading, autosave with undo and redo, per-image progress tracking, and structured JSON export.
Is the tool free to use?
Yes. PixLab Annotate ↗ is free to use and does not require an account before you can load images, create labels, or export annotation data.
Are images uploaded to the cloud?
No. Source images are loaded and processed locally in your browser. PixLab Annotate ↗ does not transfer those images to PixLab servers.
Do I need to create an account to use Annotate?
No account is required. Open the tool ↗, select images from your device, and begin labeling. Annotation state is kept in browser storage.
What export format does PixLab Annotate support?
PixLab Annotate exports one structured JSON file per image, with annotation coordinates in the original image's pixels, rectangle mask geometry and label metadata such as names, colors, RGB values, and visibility.
What annotation types does PixLab Annotate support?
PixLab Annotate supports rectangular bounding boxes for object detection datasets and polygons for object outlines and segmentation masks.
Does PixLab Annotate have keyboard shortcuts?
Yes. Press ? in the app, or click the keyboard icon in the left toolbar, to see them all. The main ones are V, R and P to switch tools, 1 to 9 to assign a label, Ctrl+Z and Ctrl+Shift+Z to undo and redo, Delete to remove a shape, the left and right arrow keys to change image, and Ctrl+S to save the JSON.
How do I label shapes quickly?
After you draw a shape, a small label picker opens next to it. Press Enter to keep the highlighted label, press 1 to 9 to pick one of your first nine labels, or type a new name to create a label with its own distinct color. Starting the next shape keeps the current label, so the picker never slows you down.
Can I edit or move an annotation after drawing it?
Yes. With the Select tool, click a shape to select it and drag it to move it. Drag a corner or point to reshape it, drag a polygon edge to add a point, and double-click a point to remove it. Every change can be undone with Ctrl+Z.
Can I load a whole folder of images?
Yes. Drop images or entire folders anywhere on the page, or use the open a whole folder option. Images load in natural order, so img2 comes before img10, and files that are not images are skipped.
How can I track progress on a large image batch?
Mark each image as done with the Done button or the D key. The header shows how many images are done, and Next to do or the N key jumps to the next image that is not done yet. Done marks are kept in your browser.
Can I continue work later on the same device?
Yes. PixLab Annotate ↗ saves your annotations automatically in browser storage while you work, so you can close the tab and continue later in the same browser on the same device. Clearing that storage removes the saved state, so use Save JSON to keep a permanent copy.

Label Images Locally Without a Cloud Upload

Open PixLab Annotate in a modern browser, select images from your device, and create bounding box or polygon labels. Your source images remain on the device.

In-browser image processing No account required Structured JSON export Keyboard shortcuts
Start Labeling Locally