Browser-local G-code viewer

Free G-code Viewer

Open a sliced G-code file locally, inspect parsed layers and review practical preflight details before printing. This G-code Preflight Checker only reads the file; it never uploads, runs, sends or changes G-code.

Open a G-code file locally

Choose a plain-text .gcode, .gco or .gc file up to 25 MiB. A source line over 4,096 characters is unavailable.

Read-only browser inspection — your file is not uploaded.

Owned thin-wall bars sliced with PrusaSlicer 2.9.6. Preview-only CLI exports: do not send these files to a printer.

Try an example

Question to explore

Absolute E and resets - what can this parser establish?

Settings: Initial logical XYZ/E zero; millimetres; absolute XYZ/E.

Example file

Downloads this public control, then opens it locally. Your own file can still be chosen above.

Read the explanation · Download and compare controls · Methods and processing

Carry a slicer estimate into finish planning

A supported duration comment is the slicer estimate, not a recreation of firmware timing. For an illustrative comparable job that took 6 hours against a 5-hour estimate, an observed correction factor is 1.2. Use it cautiously for similar work and avoid adding warm-up twice.

Interpret the result and choose the next step

The finish planner resolves a chosen start in a timezone and adds elapsed duration across midnight and daylight-saving changes. It accepts supported text G-code duration metadata and manual edits. It does not monitor a running printer or infer accurate elapsed time from STL size.

Estimate the finish date and time

Retained Arachne slicer export: inspect only, never run on a printer

Parsed paths are only part of the machine instructions

This browser-local review supports common linear moves and coordinate/extrusion mode changes. G2/G3 arcs are not included in preview extents. Unsupported or malformed commands are disclosed; macros, tool changes and firmware dialect behaviour need the exact machine documentation.

With absolute millimetre coordinates and absolute extrusion, G1 X20 E1 followed by G1 X40 E1 has a move with extrusion, then a move without additional extrusion. Under relative extrusion the same E1 fields mean something different. Confirm mode commands before interpreting paths.

The retained Classic example export was generated with PrusaSlicer 2.9.6 for software inspection. It is not a qualified machine profile and should not be executed on a printer. Preview does not certify temperatures, start/end routines, homing, usable motion limits or machine safety.

Use the G-code review procedure, the original slicer and your exact printer profile for the final decision. Parsed layer counts and duration comments are observations, not measured print time.