Droptime Logger — free, open-source roast logging
The logger that can’t lose a roast.
A free desktop app for Mac and Windows that logs your roasts live from your machine. Local-first, open source, and set up in about three minutes. It’s complete, it’s yours, and it stays that way.
Intel Mac? Download the Intel .dmg · v0.2.0 · ~15 MB · no account · release notes
Mac builds are signed and notarized by Apple — download, drag to Applications, open. On Windows, SmartScreen may warn (signing is coming): click “More info,” then “Run anyway.”
~3 min
Plug in to live temperatures
0
Samples lost to a force-quit
.alog
Artisan import & export
AGPL
Open source, on GitHub
WHAT IT DOES
Built around the twelve minutes that matter.
Three minutes, not an afternoon
Setting up roast logging is still, in 2026, an evening of serial ports, baud rates, and driver forums. The Logger’s setup wizard does that part for you: plug in, scan, and it recognizes your roaster’s data frames on its own. You see live per-channel numbers and tap which one is bean temp. No baud-rate guessing.
- Port sniffer scans your serial ports and recognizes TC4-style frames
- Name your channels from live readings — BT and ET, confirmed by eye
- No hardware yet? A built-in replay mode plays real roasts, two clicks in
The wizard
Scanning ports… TC4 frames found on usbserial-0231 · Channel 1 reads 386°F — that’s your bean probe. Tap to confirm.
Every sample hits disk before the screen
A roast is a twelve-minute physical event you can’t re-run because your logger crashed. So the Logger writes every sample to a local database on your machine before it’s allowed to draw it. Force-quit the app mid-roast, reopen it, and the recording resumes from the last saved sample.
- Local-first: your roasts live on your disk, not on our servers
- Crash recovery reattaches to the roast in progress — nothing lost
- Unplug/reconnect mid-roast is handled the same way
The rule
Store before draw — enforced in the capture engine, not the UI. There is no code path where a sample reaches the screen without reaching disk first.
Roast against a previous roast
Pick a reference roast and it rides the live chart as a ghost, aligned at charge — with a heads-up before each of its milestones, on screen and spoken aloud if you want, so your eyes can stay on the drum. Auto CHARGE and DROP detection is on by default, and the numbers roasters actually watch never leave the screen.
- “First crack on the reference in about 30 seconds” — spoken, optional
- Rate of rise, phase percentages, and DTR stay on screen the whole roast
- Auto CHARGE/DROP on by default; toggle it off if you’d rather tap
Mid-roast
Ghost: Roast 9 — Jun 27, aligned at CHARGE · next cue: FC in ~30s · RoR 17.1 · Maillard, 3:00 in.
Your data was never ours to hold
Import your entire Artisan history in one drag-and-drop. Export any roast — or all of them — as .alog, CSV, or JSON, anytime. No account, no sync requirement, no format you can’t leave with. The same files drop straight into the Droptime app when you want analysis on top.
- Artisan .alog import and export, both directions
- CSV and JSON export for anything else you use
- No account. The app works completely offline
Exit, tested
Export everything → .alog + CSV + JSON. The files re-import into Artisan and into Droptime. That’s the whole point.
A scope, not a controller.
The Logger reads temperatures and never actuates your machine. That’s not a setting — the serial driver’s command set has no write commands to send. Your burner answers to you.
HARDWARE
Will it work with my roaster?
Honest answer, machine by machine. v0.2.0 captures live from TC4-compatible rigs; the driver matrix grows from there, in the open.
TC4 / aArtisanQ-compatible rigs
Most DIY builds and many Skywalker setups
Supported todayPhidgets
Common on commercial drum rigs
NextMODBUS
Loring/Giesen-class machines
NextAillio Bullet
USB protocol under evaluation
InvestigatingKaleido
Protocol under evaluation
InvestigatingRoast on something else? The built-in port sniffer generates a diagnostic block you can paste into a device-report issue — ten minutes of your time, and that’s genuinely how the driver roadmap gets ordered.
OPEN SOURCE
Built in the open, on purpose.
The Logger is AGPL-3.0, and the code is public. We built it clean-room out of respect for Artisan — fifteen years of prior art that taught everyone what roast logging is — and the protocol docs are Apache-2.0 so driver authors can build on them freely.
Contributions are welcome, from a typo fix to a new machine driver — the serial emulator means you can write and test a driver without owning the roaster.
Read the source
The whole app — Rust capture engine, UI, drivers.
github.com/DropTime-Software/droptime-logger →
Contribute
CONTRIBUTING covers the CLA and the clean-room provenance rules.
Contribution guide →
File a device report
Paste the sniffer’s diagnostic block; get your rig on the roadmap.
Open an issue →
Sync is here. The Logger still doesn’t need it.
Sign in from the Logger and your roasts sync to your Droptime account on their own — an AI readout over each one, visible to your team. Shipping in beta now. Prefer to stay fully local? The bridge is still there — export .alog and drag it into Droptime’s roast logging, and today’s roast gets its readout today.
The Logger stays complete and free either way — that’s the deal, and the license enforces it.
FAQ
Fair questions
Free forever, and it’s open source under AGPL-3.0 — the license outlives any pricing decision we could ever make. The Logger is a complete tool, not a trial: local data, full export, no account. Droptime the company plans a paid cloud layer (sync, AI readouts, team features) on top — that’s how the free tool stays funded, and it’s optional.
No — it’s a scope, not a controller. The Logger reads temperatures and never actuates your machine. The serial driver is read-only by construction: its command set simply has no write commands. If you want software that drives your burner, Artisan is excellent at that.
Neither. The Logger works completely offline, and there’s nothing to sign up for. Everything is stored in a local database on your machine and exports as .alog, CSV, or JSON whenever you want it.
v0.2.0 captures live from TC4/aArtisanQ-compatible rigs — most DIY setups and many Skywalker conversions. Phidgets and MODBUS (Loring/Giesen-class) drivers are next; Bullet and Kaleido are under investigation. If your rig isn’t supported, the built-in port sniffer generates a diagnostic block you can paste into a GitHub device-report issue — that’s genuinely how we order the driver roadmap.
Code-signing certificates are in progress and didn’t gate the release. This version: on macOS, right-click the app and choose Open the first time; on Windows, click “More info,” then “Run anyway.” The source is public if you’d rather build it yourself.
Sign in to Droptime Cloud from the Logger and your roasts sync on their own — each one charted, compared, and read out in your account. Prefer to stay local? Export .alog and drag it into Droptime by hand instead. The Logger stays complete and free either way.
Roast tonight on it.
Download, plug in, and the wizard finds your roaster. No hardware handy? Replay mode plays a real roast in two clicks — and the Droptime demo shows where the data goes next.
Intel Mac? Download the Intel .dmg · v0.2.0 · ~15 MB · no account · release notes
Mac builds are signed and notarized by Apple — download, drag to Applications, open. On Windows, SmartScreen may warn (signing is coming): click “More info,” then “Run anyway.”