software
3D printer firmware: Marlin, Klipper, and what each means in practice
What firmware does a 3D printer run and do I need to change it?
Most consumer 3D printers ship with Marlin or a manufacturer fork of Marlin. Klipper is a popular alternative that moves computation to a Raspberry Pi and enables faster tuning cycles and advanced features. RepRapFirmware runs on Duet boards and is a full-featured third option. You usually do not need to change firmware unless you are upgrading hardware or chasing advanced features.
What firmware does in a 3D printer
Firmware is the software that runs on the printer's control board. It interprets the G-code the slicer produces, drives the stepper motors, reads temperature sensors, manages heating, triggers endstops and probes, and coordinates every movement the printhead makes. Without firmware the hardware does nothing. The firmware is what connects a file on your computer to a finished print.
Most manufacturers ship printers with a pre-compiled firmware image that has sensible defaults for that specific machine. For many users that pre-installed firmware is perfectly adequate for years of printing. Flashing custom firmware makes sense when you add hardware the stock firmware does not support, when you want advanced features like input shaping or pressure advance, or when the stock firmware has a known bug the manufacturer has not fixed.
Marlin: the dominant FDM firmware
Marlin is open-source, free, and runs on a wide range of control boards, from cheap 8-bit boards to 32-bit ARM boards. It is probably the most widely deployed 3D printer firmware in the world and forms the basis of most manufacturer forks. Marlin runs directly on the printer's control board with no additional hardware required.
Configuring Marlin means editing two header files, Configuration.h and Configuration_adv.h, enabling or disabling features with preprocessor macros, and compiling the result with PlatformIO. For stock printer firmware you typically just flash a pre-compiled release. Custom builds are needed when adding hardware like a BLTouch or a CR Touch, switching to a different thermistor, or enabling features the manufacturer disabled. The Marlin documentation is thorough and the community forums are well developed.
Klipper: computation moves to a host computer
Klipper splits firmware duties between the control board and a host computer, almost always a Raspberry Pi running Klipper's Python daemon. The control board handles the time-critical motion, while the Raspberry Pi handles computation, configuration, and the web interface. Mainsail and Fluidd are the two most popular browser-based dashboards for Klipper; Mainsail is generally considered slightly cleaner.
The main Klipper advantages are faster tuning cycles and two killer features: input shaping and pressure advance. Input shaping uses an accelerometer to measure resonance frequencies in the printer frame and then applies a digital filter to reduce ringing artifacts at high speeds, sometimes allowing much faster printing without visible quality loss. The configuration lives in a human-readable text file that you edit via the web interface without recompiling anything, which makes iteration fast. The tradeoff is that Klipper requires a Raspberry Pi or similar single-board computer and has a steeper initial setup than flashing a Marlin binary.
RepRapFirmware: Duet boards and precision machines
RepRapFirmware is maintained by Duet3D and runs on Duet control boards, which are popular in high-end custom builds, CoreXY machines, and delta printers. It is configured entirely through G-code macros stored in a text file rather than compiled C++ headers, which makes reconfiguration fast once you understand the syntax. The Duet hardware and RepRapFirmware together are known for reliable performance on demanding builds.
RepRapFirmware is less common than Marlin or Klipper in consumer-grade printers, but it is worth knowing about for anyone building a custom machine or looking at the premium end of the market. The main reason to choose it is the Duet board ecosystem and the macro-based configuration approach.
Should you flash custom firmware?
For most users the honest answer is no, at least not initially. Stock firmware on a well-supported printer works and the risk of a bad flash or incorrect configuration bricking a board is real if you are inexperienced. The right time to flash firmware is when you have a specific hardware addition that requires it, like a new probe or a different extruder type, or when a well-documented upgrade path like switching to Klipper offers a concrete benefit you need.
If you do flash: back up your existing firmware binary first if you can retrieve it, use the correct board target and upload method for your specific hardware, double-check your configuration against your actual hardware before powering on heaters, and PID-tune your hotend and bed after any firmware change. The slicer and calibration matter more to print quality than firmware version for most users on stock hardware.
Common questions
Frequently asked questions: 3d printer firmware
What is Klipper and why do people switch to it?
Klipper is open-source 3D printer firmware that offloads computation from the printer's control board to a host computer, usually a Raspberry Pi. People switch for two main reasons: input shaping, which uses an accelerometer to measure and cancel frame resonance and often allows faster printing with less ringing, and pressure advance, a more accurate version of linear advance that reduces corner blobbing. Both features are also available in Marlin, but Klipper's text-file configuration makes tuning them faster since you do not need to recompile.
Is Marlin still good firmware in 2024 and 2025?
Yes. Marlin is actively maintained, runs on a huge range of boards, and produces excellent results on well-tuned machines. Most consumer FDM printers ship with a Marlin fork. Klipper has advantages for advanced tuning and faster iteration, but Marlin is not obsolete. If your printer already runs Marlin and prints well, there is no reason to switch unless you have a specific reason.
Can I brick my printer by flashing firmware?
Yes, if you flash firmware compiled for the wrong board or with an incorrect configuration for your hardware. The most common risks are using the wrong upload method for your bootloader, incorrectly setting thermistor types (which can disable thermal runaway protection), and configuring endstop polarity wrong. The printer will usually survive but you may need to re-flash or troubleshoot a non-functional machine. Back up your existing firmware binary first, verify the board target, and read the documentation for your specific hardware.
What is the difference between Marlin and Klipper for input shaping?
Both support input shaping (Marlin calls it resonance compensation), but the workflow differs. Klipper's input shaping is configured by running an ADXL345 accelerometer measurement from inside the running system and pasting the resulting frequencies into a text file with no recompile. Marlin's version requires editing the configuration, recompiling, and reflashing the firmware. For rapid iteration Klipper's approach is considerably faster. For a one-time setup on a stable machine the difference is less important.
What is pressure advance and does my printer support it?
Pressure advance (sometimes called linear advance in earlier Marlin versions) compensates for the delay between when a stepper motor pushes filament and when pressure builds at the nozzle. It reduces corner blobbing and over-extrusion at speed changes. Most modern Marlin builds and all current Klipper installs support it. Whether your specific printer's stock firmware has it enabled depends on the manufacturer. You can check by sending M572 in Marlin (linear advance K value) or checking your printer's settings menu.
Do I need to flash firmware to use a BLTouch or CR Touch?
Yes, for most printers. Auto bed leveling probes like BLTouch and CR Touch require firmware support to read the probe's signal and apply the mesh compensation. You need to enable the probe type and pin assignment in your firmware configuration and recompile, or use a pre-compiled binary specifically built for your printer model with that probe. Some printers support a limited probe via a plugin without reflashing, but full mesh compensation generally requires firmware support.
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