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Python

Connect directly to Foxglove or play back local data recorded with the Python SDK.

Install the SDK​

The SDK is distributed through PyPI. You can get started with a new project or use Foxglove from a notebook.

The exact installation will depend on your package manager; here's an example using uv.

uv init example
cd example
uv add foxglove-sdk

Live data​

Log messages from Python​

Edit the generated main.py:

import foxglove
import time

foxglove.start_server()

while True:
    foxglove.log("/hello", {"time": time.time()})
    time.sleep(0.03)

Run the script​

Run the script to start logging. Following the uv example above, you can run the following command from the "example" directory:

uv run python main.py

Connect​

In Foxglove, select "Open connection" from the dashboard or left-hand menu.

Select open connection

Select "Foxglove WebSocket" in the "Open a new connection" dialog, then click "Open" to accept the default connection string:

Foxglove WebSocket dialog

Local data​

Recording data to a file​

The SDK can also log data to disk. Let's augment the example above to also produce an MCAP file which can later be opened in Foxglove:

import foxglove
import time

foxglove.start_server()

# Keep a reference to the mcap. It will automatically close the file when the program exits, but
# we could also close it manually with `mcap.close()`.
with foxglove.open_mcap("example.mcap"):

    while True:
        foxglove.log("/hello", {"time": time.time()})
        time.sleep(0.03)

Viewing data from a file​

Open your recording(s) directly from your computer by:

  • Dragging and dropping them into Foxglove
  • Using Cmd/Ctrl + o
  • Clicking Open local file(s) in the app

Local file dialog

Opening multiple files together combines them into a single merged data source, as if they came from one recording. This is useful when the files belong to the same recording, for example a single recording split into multiple segments, or a main recording plus a related file such as a separate transforms log. The files must be of the same format.

To keep sources separate and view their data together on a shared timeline, use Comparison mode instead.

Explore your data​

Your data is now available for exploring in Foxglove. Add some panels to begin visualizing what your robot is seeing and producing. Not sure where to start? Try adding a Raw Messages panel, Plot panel, or 3D panel.

To list available topics, open the left sidebar and open the Topics tab.

Topics tab