Free Online STL to G-Code Converter

• 100% free with no sign-up required
• Browser-based — works on Windows, Mac, and Linux
• Supports standard FDM printers including Ender, Prusa, and Creality
• Adjust layer height, infill, supports, and temperature settings
• Fast conversion — most files process in under 30 seconds
• Secure: your files are never stored on our servers

An STL to G-Code converter — also called a slicer — translates a 3D model stored in STL (Standard Tessellation Language) format into G-Code, the machine language your 3D printer reads. G-Code tells the printer exactly how to move, how fast to extrude, and at what temperature to operate. Our free online slicer makes this process simple without downloading any software.

Our tool generates standard G-Code compatible with most FDM desktop 3D printers including Creality Ender 3, Prusa i3, Anycubic, Artillery, and more. Input format: .STL (binary and ASCII). Output format: .gcode.

Hobbyists & Makers

Ideal for fast validation of your STL files and quick configuration of standard settings. Makers can easily convert files and tweak layer height or infill without waiting for heavy desktop applications to open.

Educators & Makerspaces

Perfect for showing students the mechanics of slicing and G-code generation directly in the browser. No installation or complex system configuration is needed, making it easy to run on Chromebooks and school computers.

Prototyping Engineers

Enables rapid prototyping and validation of design tolerances on-the-fly. Engineers can quickly generate G-code locally to test geometries on standard FDM printers before pushing designs to full production.

Cosplay & Prop Makers

Helps prop designers split and prepare complex assemblies for FDM printing. Quickly verify dimensions, evaluate support placement, and generate ready-to-use G-code for large costume builds.

Does This Work With GX Files?

Perimeters & Wall Structure

Perimeters, also referred to as wall loops or shells, form the outer boundary of your 3D printed model. The number of perimeters you configure directly affects the component's structural strength, water tightness, and overall printing time. Each additional wall loop adds a solid line of plastic around the outline, which is significantly stronger than infill. For structural parts, increasing the wall count from 2 to 4 is often more effective than raising the infill percentage. However, more perimeters mean the print head must trace the outlines multiple times per layer, increasing print duration and filament usage. Finding the right balance between shells and infill is key to optimizing print jobs.

Infill Patterns Explained

Infill patterns define the internal structure of your printed part, balancing weight, material cost, and strength. Standard patterns like Grid and Lines are fast to slice and print because they use linear paths, making them ideal for simple models that do not face physical stress. In contrast, Gyroid and Honeycomb patterns provide multi-directional strength. The Gyroid infill uses a continuous wave structure that prints quickly and provides equal strength in all three axes (X, Y, Z) while preventing internal shearing. Honeycomb offers maximum structural rigidity but increases print times due to frequent direction changes. Select your infill density and pattern based on whether your part needs speed or strength.

Understanding Retraction

Retraction is the process of slightly pulling filament backward out of the hotend nozzle before the print head performs travel movements. This relief of pressure prevents molten plastic from leaking, which is the primary cause of stringing and oozing between separate parts of a print. The optimal retraction settings depend heavily on your extruder configuration. Bowden extruders, which push filament through a long PTFE tube, require longer retraction distances, typically between 4.0mm and 6.0mm. Direct drive extruders sit directly above the hotend and need much shorter retraction distances, usually between 0.5mm and 1.5mm. Correctly calibrating retraction speed and distance ensures clean, string-free surface finishes.

Print Speed vs Quality Tradeoffs

Print speed is a crucial setting that dictates how fast the extruder moves while depositing filament. While high print speeds reduce overall print times, they can severely compromise layer adhesion and surface finish. Fast movements give the molten plastic less time to bond with the layer below, reducing the part's mechanical strength. High speeds can also trigger vibrations, leading to surface artifacts like ringing or ghosting. For optimal results, use lower speeds (30-40mm/s) for outer perimeters to ensure fine surface detail, and higher speeds (60-80mm/s) for infill where visual aesthetics do not matter. Finding this balance helps maximize output speed without sacrificing the integrity of the part.

When we started building 3D printing workflows, we noticed a persistent barrier for casual users and newcomers: the friction of downloading large desktop slicing utilities just to prepare simple models or adjust basic parameters. Many online converters promised a solution, but they required uploading proprietary STL designs to external servers, creating privacy risks and latency issues.

We believed there was a better way. By leveraging modern browser standard techniques and compiling slicing runtimes into highly optimized WebAssembly, we built a slicer that runs entirely client-side. Your designs never leave your local system, offering absolute privacy, zero bandwidth overhead, and rapid G-code generation.