Settings and privacy
ThermalPrint has no settings window. It remembers your choices as you make them, in small text files in your home folder. You can read or delete them at any time.
What is remembered#
| What | Remembered? |
|---|---|
| Selected printer, media, resolution, size, DPI, rotation, margin, scale, copies | Yes, and kept separately for each printer. |
| Alignment offsets | Yes, per printer. |
| Safe margin (0 to 10 mm) | Yes, per printer. Off (0) by default. |
| Sidebar collapsed or expanded | Yes. |
| Watch folder and whether it is on | Yes. |
| Move printed labels to a Processed folder | Yes. Off by default. |
| Printer for watched labels | Yes. Current printer by default. |
| Print labels automatically, the file-name filter, and Most per minute | Yes. Off by default. The first-time warning is remembered once you accept it. Pausing is not remembered. |
| Skip review for automatic crops, and Keep going if a label fails | Yes. Both off by default. |
| The Get ready to print checklist on Home | Hidden for good once you press Hide this. |
| Recent documents (up to 8 file locations) | Yes. |
| Recent prints (up to 50) | Yes, in a separate file. |
| Window size and position | Yes. |
| The print queue in Import & Convert | Yes, as file locations, pages, and crops. At the next start you choose Restore or Discard. Review states are not kept. |
| Recent messages | No. The list behind the Messages button is cleared when you quit. |
| Your label designs | Only as the .thermalprint files you save yourself, plus a recovery copy while changes are unsaved. |
| Your templates, logos, fonts, and address book | Yes, in the folders listed below. |
Where your data lives#
| File | Holds | Normal install | Snap |
|---|---|---|---|
settings.json | Preferences and printer profiles | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
history.json | Recent prints | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
templates/ | Designs saved with Save as template… | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
logos/ | Images saved with Save as logo | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
fonts/ | Fonts you added to text objects | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
addresses.json | The address book | ~/.config/thermalprint/ | ~/snap/thermalprint/current/.config/thermalprint/ |
recovery.thermalprint | A copy of unsaved changes, removed when you save or discard | ~/.local/share/thermalprint/ | ~/snap/thermalprint/current/.local/share/ |
app.ron | Window state | ~/.local/share/thermalprint/ | ~/snap/thermalprint/current/.local/share/ |
To start fresh, quit ThermalPrint and delete these files. A damaged or hand-edited settings file is checked when it is read: impossible values are corrected, and an unreadable file is ignored.
Recent documents and recent prints contain file names and locations, and a printed design's contents. Use Clear history in Print Center before sharing your settings folder.
Privacy#
- Your labels stay on your computer. Documents are processed locally. ThermalPrint does not upload anything and does not connect to any marketplace or carrier account.
- There is no tracking, analytics, or account.
- The app opens your web browser only when you press a link or the Help button.
- When printing, labels go to the printer system on your computer (or the network printer you chose).
Built-in limits#
| Limit | Value |
|---|---|
| Imported file size | 256 MB |
| Imported page or image size | 45 megapixels |
| Output size | 36 megapixels (lower the DPI or label size if you reach it) |
| Label size | 10 to 500 mm per side in Import & Convert; 1 to 2,000 mm in the Designer canvas |
| Copies | 1 to 999 |
| Alignment offset | −10 to +10 mm |
| Batch CSV | 500 rows, 64 columns, 2 MB |
| Barcode or QR content | 2,048 characters |
| Image inside a design | 9 MB |
| Logo inside a QR code | Stored at up to 256 pixels; the clear box is 10 % to 30 % of the code's width |
| Objects in one design | 1,000 |
| Font size / line width | 3 to 300 pt / 0.05 to 20 mm |
| Your own templates / logos / fonts | 100 / 60 / 50 (fonts up to 20 MB each) |
| Address book | 500 addresses (name up to 100 characters, address up to 600) |
| Number range | 1 to 10,000 labels per run |
| Sheet | Up to 50 columns and 50 rows per page, 5,000 labels |
| Text line spacing / bottom margin (auto-length) | 0.5 to 3 times / 0 to 50 mm |
| Watch folder | Files up to 50 MB; up to 20 new files per check; a check every 2 seconds |
| Automatic printing | 1 to 60 labels per minute (default 10); a 5-second countdown before each; a file-name filter of up to 200 characters |
These limits protect against accidental memory exhaustion. They are not a security sandbox for untrusted files; open labels only from sources you trust.
Environment variables#
| Variable | Effect |
|---|---|
THERMALPRINT_PDFIUM_DIR | Folder containing libpdfium.so, to use PDFium instead of Poppler. |
CUPS_SERVER | Use a different CUPS server. A path to a socket is supported; remote servers are not used for reading printer details. |
RUST_LOG=thermalprint=debug | Print diagnostic details to the terminal. Keep logs private; they can include file paths. |
LC_ALL, LC_MESSAGES, LANGUAGE, LANG | Your system language, which ThermalPrint follows (Spanish, German, French; otherwise English). |