ROSbagScan is a browser-based tool for loading, comparing, and plotting ROS 2 rosbag2 data from MCAP and SQLite3 files.
Current development release: v0.1.3.
ROSbagScan uses Semantic Versioning with major.minor.patch. Major version 0 indicates active development.
Version 0.1.0 is the first release under the ROSbagScan name. Project ZIP files exported by ROS2bag Analyzer v0.0.18 remain importable.
Open the web application with the AI Challenge 2026 sample project and rosbag:
GitHub repository:
https://github.com/covao/ROSbagScan
- Show the imported Project ZIP filename in the Project menu
- Rename a replaced dummy dataset to the imported rosbag filename
- Use signal-specific colors and matching color dots on removable signal chips for multi-signal Time plots when one rosbag is enabled
- Use a simplified Time cursor label and a high-contrast white cursor line in dark mode
- Editable plotter names and per-dataset line colors
- Dummy project datasets are replaced by matching real rosbags while preserving line colors
- Signal search includes engineering-unit text
- Reuse the smallest available Plotter number when a plotter is added.
- Hide signal and GeoJSON chips in X-Y mode to maximize graph area.
- Use a stronger GeoJSON outline and synchronized cursor line for visibility.
- Dark and light UI themes.
- Maximize any plotter to fill the workspace.
- Import GeoJSON road outlines into an X-Y plotter and render them as a background layer.
- Save and restore GeoJSON layers inside Project ZIP files.
- Project ZIP export/import for datasets and plotter setup
- Optional dummy MCAP export with first/last messages only
- Collapsible Rosbag data and Signals menu trees
- Signal checkboxes for the active plotter
- Synchronized cursor playback across plotters
- Load ROS 2 rosbag2 data from
.mcap,.db3, and.zipfiles. - Load files with the file picker or drag and drop.
- Load a Project ZIP from a URL with the
#project=URL parameter. - Load one or more rosbag files from URLs with repeated
#rosbag=parameters. - Keep compatibility with the legacy
#zip=URL parameter. - Load multiple rosbag datasets and compare the same signals.
- Enable or disable each rosbag dataset with a checkbox.
- Use a fixed line color for each rosbag dataset.
- Drag signals from the Signals menu to any plotter.
- Add, remove, and reorder plotters.
- Switch each plotter between Time and X-Y modes.
- Automatically switch to X-Y mode for recognizable X/Y signal pairs.
- Show lines with optional point markers.
- Use a synchronized cursor across all plotters.
- Move the synchronized cursor by clicking on plot data.
- Select one, two, or three plotter columns.
- Display signal names and inferred engineering units when available.
- Decode ROS 2 CDR messages using message schemas stored in MCAP files.
- Run entirely in the browser without uploading rosbag data to a server.
- A modern web browser
- WebGL enabled for accelerated Plotly rendering
- Recommended: latest Chrome, Edge, Firefox, or Safari
- Internet access for CDN libraries, or local library files for offline use
Open ROSbagScan.html in a supported browser or serve it from a local web server. Load one or more rosbag files with the Open files icon or drag and drop .mcap, .db3, or .zip files into the application. Select the rosbag datasets to display, then drag signals from the Signals menu onto a plotter. Add more plotters from the title bar and select Time or X-Y mode for each plotter.
Load the sample ROSBag into the dummy-data project
The rosbag supplied by the rosbag parameter replaces the single dummy dataset regardless of its recorded time range.
To load multiple rosbag datasets, repeat the rosbag parameter. Each URL is loaded as a separate dataset:
ROSbagScan.html#rosbag=https%3A%2F%2Fexample.com%2Frun1.mcap&rosbag=https%3A%2F%2Fexample.com%2Frun2.mcap
Comma-separated values are also accepted. bag and mcap are aliases, and the existing zip parameter remains supported for rosbag ZIP files. A Project URL can be combined with rosbag URLs; the Project is imported first and the rosbag datasets are then added.
Remote servers must allow cross-origin access (CORS). Encode URLs when they contain &, #, or other characters that have meaning in the browser URL.
For an X-Y plotter, click the ⌗ button to import a .geojson or .json file. Polygon and line geometries are rendered as road-outline background layers. Project Export automatically includes the imported GeoJSON files, and Project Import restores them.
- ROS 2 rosbag2: ROS 2 bag recording and playback framework.
- MCAP: Container format for timestamped robotics and pub/sub data.
- Plotly.js: JavaScript plotting library used for interactive plots.
- sql.js: SQLite compiled to WebAssembly for reading rosbag2 SQLite3 files in the browser.
- JSZip: JavaScript library used to read ZIP archives in the browser.