MF4 viewer online
Open an MF4 (ASAM MDF 4) CAN bus log in your browser. FreeCAN Studio reads MF4 bus logging files that store the raw CAN frames, decodes them with a DBC and plots signals, without uploading anything.
Free. No account.
Open an MF4 fileFiles are processed on your computer and never uploaded.
How to open an MF4 file online
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Open the app
Go to app.freecanstudio.com in a desktop browser. There is nothing to install and no account to create.
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Open the MF4 file
Click Open Log… and choose the .mf4 file, or drop it anywhere on the window. It is read on your computer, and the frames appear once the whole file has been read.
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Decode and explore
Click Open DBC… to add the database for your bus. See every ID in Overview, read frames in Trace and plot signals in Plot.
Questions
Which MF4 files does it open?
MF4 bus logging files: recordings that store the raw CAN frames (CAN data, remote and error frames, classic CAN and CAN FD), as many CAN data loggers write them, compressed or not. FreeCAN Studio works from raw frames, so a file that holds only already-decoded measurement channels has nothing for it to show. Files up to 1 GB are read, as long as their frames fit in your browser's memory: a 112 MB file of 10 million frames takes about 0.6 GB. Older MDF 3 files do not open.
Is my MF4 file uploaded?
No. FreeCAN Studio runs in your browser: a Rust core compiled to WebAssembly reads the file on your computer. The app loads nothing from third parties, and its Content-Security-Policy makes your browser enforce that. How to check it.
Do I need a DBC file?
No. Without one you still see every ID with its count, period and bit activity. Add a DBC to decode the frames into signals you can plot.
Can I plot signals from an MF4 log?
Yes, once a DBC decodes the frames. Plot shows signals in stacked lanes on one time axis, with A and B cursors and a full-log minimap.
Which browsers does it run in?
Current desktop versions of Chrome, Edge, Firefox and Safari. Phones and tablets are not supported.
Is it free?
Yes. FreeCAN Studio is free and needs no account. FreeCAN Studio Pro, a paid desktop app, is planned separately.
No log at hand? Try FreeCAN Studio on a 1,000,000-frame demo log and its DBC.
Try the Demo