What Is Klipper? Firmware for 3D Printers Explained

Klipper is 3D printer firmware that moves most of the heavy calculation off the printer's control board and onto a separate small computer. The printer still has its own board, but that board mostly follows instructions. This guide explains how that split works, what Klipper adds, what you need to run it and who should think twice. Everything here comes from the official Klipper documentation, not from our own printing, so treat any numbers as the project's claims.

What does Klipper do?

Firmware is the software that runs on a printer's control board and turns G-code from your slicer into motor moves, heater control and fan speeds. Most printers ship with firmware such as Marlin that does all of this on the board itself. Klipper does it differently.

According to the Klipper documentation, an application processor (such as a low-cost Raspberry Pi) calculates when each stepper motor should step. It compresses those events, sends them to the micro-controller on the printer board, and the micro-controller executes each event at the requested time. The docs state that each stepper event is scheduled with a precision of 25 microseconds or better.

The two halves have names in the docs: the host is the Linux device (the Raspberry Pi or similar) and the MCU is the printer board.

What does Klipper add?

The project's features page lists several things that users usually mention:

• Config file instead of reflashing. All settings are in a standard text file (printer.cfg) on the host. Editing a value does not require flashing the board again.
• Pressure advance. A way to account for pressure inside the extruder. The docs say it reduces extruder ooze and improves the quality of corners. See our retraction settings guide for the related idea of managing ooze.
• Input shaping. Reduces the effect of vibrations. The docs say it can reduce or eliminate ringing (also called ghosting or echoing) and may allow faster printing at similar quality. Our guide to fixing ghosting and ringing covers the symptom.
• Macros. New G-code commands can be defined in the config file, and they can behave differently depending on printer state.
• Built-in API server. A JSON based interface that lets other software control the printer.
• Bed leveling and probing. Basic bed tilt detection or full mesh leveling, with support for many Z probes. See auto bed leveling explained.
• Exclude object. When configured, it lets you cancel one object in a multi-part print.

Klipper also supports many machine layouts, including cartesian, delta, CoreXY and several others listed in the docs. If you are unsure what those words mean, see CoreXY versus bed slinger printers.

What do you need to run Klipper?

The installation guide describes flashing Klipper to the printer board as a step, so you need to be comfortable following command line instructions. Mainsail publishes a ready-made image called MainsailOS for Raspberry Pi and some Orange Pi boards, and a third-party installer called KIAUH can install Klipper and Fluidd. Check the install guide for your exact board, because flashing methods vary a lot between boards.

How do you control a Klipper printer?

Klipper supports common LCD displays wired to the printer, but day-to-day control usually happens from a browser. The docs say the best choices are front ends that talk to Klipper through the Moonraker web API, and that you can also use OctoPrint. The two main Moonraker based options are Mainsail and Fluidd. All of them are used from a normal web browser on the same network. If you want to compare with the OctoPrint route, read what OctoPrint is.

Your slicer still does the slicing. Klipper only runs the G-code it produces. If you are new to that step, start with what a slicer is.

Who is Klipper for?

This section is opinion based on the documentation, not on our own use.

• Good fit: people who like adjusting their printer, already own a printer with a Klipper config available, or build their own machine.
• Poor fit: anyone who wants to unbox a printer and print. Klipper adds a computer to maintain, a config file to understand and a flashing step that can go wrong.

Before adding Klipper to a printer you already own, check that a config exists for your exact model (the install guide suggests the Klipper config directory or the manufacturer's website) and that you can undo the change.