Overtrace is a browser-based industrial telemetry overlay tool. You load datalogs from multiple modules — compressors, gen skids, engine ECMs — and overlay every channel on one shared time axis so you can see what happened, and when, across the whole system at once.

Which datalog formats does Overtrace support?

Overtrace auto-detects Emit (Dynamic Controls), Caterpillar, Waukesha and Excel datalogs, with more formats coming. Just drop the files in and the channels are parsed and plotted automatically.

Is my telemetry data uploaded to a server?

No. All parsing happens entirely in your browser using local JavaScript in a Web worker. There is literally no upload endpoint — your datalogs never leave your machine. That privacy-by-architecture is a core part of the design.

Do I need to install anything?

No install required. Overtrace runs in any modern browser on desktop, laptop or field tablet, and works even on a spotty plant network because everything is client-side.

Can I try Overtrace before buying?

Yes. The full-featured demo runs on built-in sample telemetry, so you can try measuring, overlays and alignment for free. A license unlocks uploading your own logs, and it is tied to your account rather than a single device.

Exporting and importing session files

A session file is everything you've done to the chart, written to one file: which channels are on, their colors, scaling and axis sides, module offsets, the X-axis mode and zoom window, and every annotation, markup, lock and measure point. Reopen it a month later and the chart comes back exactly as you left it — or send it to a colleague and they see what you saw.

Exporting

Click “⇪ Export session” in the top view-toggles.
Check the filename. Overtrace suggests one stamped with the date and time, and adds the .otsession.json extension for you.
Add a note for whoever opens the file — optional, but it's the fastest way to say what to look at.
Under Contents, choose “Full session” or “Overlay only”. The estimated file size updates as you switch.
Click “Export”. The file is written to your browser's downloads.

Full session vs Overlay only

Full session — includes the parsed datalog data, so the file is self-contained and the recipient needs no other files. It reproduces your exact chart, and it's the larger of the two by a long way.
Overlay only — annotations, markups, scaling, offsets, locks and measure points, plus a SHA-256 hash of each source datalog instead of the data itself. Small, but the recipient has to have the same datalogs open; overlays attach themselves to the modules whose source bytes hash to a match.

Importing

Click “⇩ Import session” and pick the file, or just drag the .otsession.json onto the window.
Read the preview: contents, the exporter's note, when it was exported, the modules it carries, and how many annotations, markups, locks and measure points are in it.
Click “Load”.

For an overlay-only file, the preview also lists which of your loaded modules it matched by source hash, and which sources it couldn't find. If some are missing, the button reads “Load anyway” and those overlays are skipped — cancel and open the missing datalogs first if you want everything. If nothing matches at all, there's nothing to attach the overlay to and the button is disabled.

If loading fails part-way through, Overtrace puts your previous chart back and tells you so. You never end up looking at a half-loaded session.

The file is JSON with a version stamp on it, so newer builds of Overtrace keep opening older session files. Open a file from a newer build than yours and you get a plain message telling you to update, rather than a broken chart.

Export and import both require a license, because a full session file can carry raw datalog data. In demo mode the buttons stay visible but render locked.

FAQ

Does the session file travel through Overtrace servers?

No. Exporting writes a file straight to your browser's downloads, and importing reads a file you pick from your own disk. Nothing is uploaded or transmitted through Overtrace's infrastructure.

How do I share a session with a teammate?

Export a Full session file and send it however you'd send any document — email, chat, a shared drive. They import it locally and see your exact chart, no datalogs needed.

What if I edit the session file by hand?

The importer validates the file before touching anything. An edit that breaks the shape produces a friendly error and leaves your current chart exactly as it was.