How to Use the Gcode viewer and simulator
Upload Your G-code File
Click “Import”to upload your .gcode file into the browser window.
View the gcode
Once the file loads, you’ll see a 3D model of your print. Use the mouse to rotate and zoom. You can pan and orbit the view to inspect all sides.
Simulate the print
Click the “Simulate” button to start the simulation.
Inspect layers
Toggle individual layers or adjust a slider to display only up to a certain height.
Edit gcode
The Edit G-code File button functions as an integrated text editor for your printing instructions.
Export
After reviewing, click the “Export” button to download the gcode file.
Online Gcode Viewer and Simulator Options
Import
Upload your gcode file or gcode example. The tool will load and process the file.
2D Viewer
Switches the view from a 3D simulation to a 2D layer-by-layer visualization. This mode is ideal for inspecting individual layers, analyzing extrusion paths, and verifying slicing accuracy.
Edit gcode file
Open the built-in G-code editor, allowing you to modify the G-code directly within the browser. This feature is useful for making quick adjustments or corrections without needing external software. For more infomation, please see our How to Use the “Edit G-code” Function section below.
Simulate
Initiates the simulation of the printing process. The toolpath is animated in real-time, providing a visual representation of how the printer will execute the G-code.(NC Viewer)
Play Speed
Adjusts the speed of the simulation playback. Options typically include: x0.25, x0.5, x0.75, x1(normal speed), x2, x10, x100, x1000.
This control helps in fast-forwarding or slowing down the simulation for detailed analysis.
Show Non-Extrusion Moves
When enabled, this option displays the movements of the print head when it's not extruding material (travel moves). Visualizing these paths can help identify unnecessary movements that might affect print quality.
Hide Print Head
This toggle hides the graphical representation of the print head during simulation. Hiding the print head can provide an unobstructed view of the model and toolpaths, facilitating better inspection of the print layers.
Show Different Speeds with Different Colors
Activating this feature color-codes the toolpaths based on their speed. Different colors represent different speeds, allowing for a quick assessment of speed variations throughout the print.
Estimated Print Time
Provides an estimate of the total time required to complete the print, based on the G-code instructions. This helps in planning and scheduling print jobs.
Total Filament Used
Displays the total length of filament that will be used for the print, calculated from the G-code. This information is crucial for estimating material requirements and costs.
Number of Layers
Shows the total number of layers that the print will have, offering insight into the print's complexity and duration.
Layer Height
Indicates the height of each individual layer as defined in the G-code. Understanding layer height is essential for assessing print resolution and quality.
Extrusion Width Simulation
Simulates the width of the extruded filament lines in the visualization, providing a more accurate representation of the final print.
How to Use the “Edit G-code” Function
Upload gcode file
Upload your .gcode file by dragging it into the viewer area or clicking the “Import” button.
Click the “Edit gcode file” Button
Clicking this opens a scrollable text pane showing the raw contents of your G-code file.
Modify G-code Text Directly
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Inside the editor pane, you can scroll through all lines of your G-code. Each line (e.g., G1 X72.88 Y89.25 E0.10334) represents a movement or command for the printer.
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Simply click anywhere in that text area and begin typing or deleting to alter commands. For example:
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Change a temperature line (e.g., M104 S200 → M104 S210);
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Insert a pause command (M0 or M25) at a specific layer;
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Remove a problematic travel move or retraction command that was causing blobs;
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As you make edits, the text area will update in real time (it’s just a plain text editor).
Confirm (Save) Your Edits
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After you’ve made your changes, click the Confirm button at the bottom of the editor pane.
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The simulator will re-parse your edited G-code, rebuild the 3D preview, and update the simulation to reflect any new commands or parameters you added.
Re-run the Simulation
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Once your edits are applied, the 3D view and animation will reflect those changes
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You can press Play, adjust Play Speed, or step through layers to verify that your tweaks had the desired effect.
Frequently Asked Questions
What is a G-code simulator?
A G-code simulator is a software tool that reads a G-code file and renders its toolpaths in 3D before printing. It helps you visualize how the print head will move and how layers will build up, without using any filament.
Why use a G-code viewer before printing?
Using a viewer lets you preview the print to catch errors or inefficiencies early. You can find missing layers, potential collisions, or other problems in the G-code before starting the printer. This avoids failed prints and wasted material.
Which file formats are supported?
3DPEA’s online gcode simulator primarily accepts standard G-code files (text files from your slicer). It also supports to convert gcode to stl or gcode to 3mf.
Which slicers and printers are supported?
Any slicer that outputs G-code is supported. For example, Cura and PrusaSlicer (Slic3r) are fully compatible. As for printers, any machine running common firmware like Marlin or Klipper will work, since the simulator just processes the G-code commands.
Do I need to sign up or install anything?
No installation or sign up is needed. it’s all online.
Is the G-code simulator and G-code viewer free?
Yes. 3DPEA offers the G-code viewer and simulator completely free online.
Can I turn the gcode file into a 3d model stl after viewing?
Yes. You can use our Gcode to STL converter to turn your gcode into a 3d stl file which is suitable for 3d printing.
Start to view and simulate Your G-code file Now!
Ready to preview your gcode fileds before printing them? Try the 3DPEA G-code Viewer and Simulator now – it’s free and runs in your browser.