# The LOKLiK iCraft Runs GPLv3 Software — And the Vendor Won't Release the Source **A firmware provenance & GPLv3 compliance report** - **Subject device:** LOKLiK iCraft desktop cutting machine - **Vendor:** LOKLiK Inc. / HTVRONT - **Upstream software:** `Grbl_Esp32` (GPLv3), by bdring (Barton Dring) — a port of Grbl, originally by Sungeon "Sonny" Jeon - **Author of report:** Rev — JMS CNC (full legal name available to the vendor / FSF / SFC on request) - **Contact:** therealrevjmoney@gmail.com - **Date:** June 2026 - **Status:** Source **published by the vendor** at [github.com/HKsjtech/LoklikIdeaStudio-Firmware](https://github.com/HKsjtech/LoklikIdeaStudio-Firmware) on **2026-06-18**, following a GPLv3 §6 request and the public release of this report — see **Update (2026-06-18)** below. --- ## Update — 2026-06-18: the vendor responded; the source is now public After the GPLv3 §6 source request and the public release of this report, LOKLiK responded and pointed to a GitHub repository containing the firmware source: **[github.com/HKsjtech/LoklikIdeaStudio-Firmware](https://github.com/HKsjtech/LoklikIdeaStudio-Firmware)**. The repository is genuine and addresses the core of this report: - It **compiles** with PlatformIO (`pio run -e release`, platform `espressif32@3.0.0`). - The build **matches the firmware on the device**: identical version string (`Grbl_ESP32 Ver 1.3a Date 20211103`) and byte-identical Grbl strings, including the leaked internal source path `Grbl_Esp32/src/I2SOut.cpp`. - It includes the vendor's machine-specific layer — `SJMachine` / `SJCutter` / `SJConfig` (`MACHINE_NAME "LOKLIK_CRAFTER_1"`) — i.e. the modified Corresponding Source this report asked for. **On disclosure and timing.** The vendor stated the code "was uploaded to GitHub back on 2023." GitHub's metadata is consistent with the *files* dating to 2023 (`created_at` 2023-09-05), but several facts indicate the repository was not, in practice, available to customers until the day the vendor replied: | Signal (GitHub API / Internet Archive, captured 2026-06-18) | Value | |---|---| | `created_at` | 2023-09-05 | | `pushed_at` | **2026-06-18** (the day the vendor replied) | | Stars / forks / watchers | **0 / 0 / 0** | | Internet Archive snapshots before 2026-06-18 | **none** (the 2026-06-18 capture is the *first*) | | Discoverable via GitHub search before 2026-06-18 | No | GitHub does not expose repository visibility history via its public API, so it **cannot be proven from outside** whether the repository was set to "private" before 2026-06-18. What *is* verifiable is that the source was referenced **nowhere a customer would encounter it** — not in IdeaStudio, the FlashTool, the product page, or the documentation — and that it was not provided until a §6 request was made and the issue was raised publicly. Raw API and Wayback data are preserved at the mirror below. **Mirror & evidence:** [github.com/revjmoney/loklik-icraft-firmware](https://github.com/revjmoney/loklik-icraft-firmware) — a clean source mirror (original commit history preserved), the distributed firmware images, the machine definitions, and the raw evidence files. **Outstanding asks.** The substantive remedy — public Corresponding Source — has been met. Two points remain for full, good-faith compliance: (1) keep the source **public and linked from the product/app**; and (2) **attribute** the firmware as Grbl_Esp32 under the GPLv3, so customers can learn what runs their machine and obtain its source. *The original report below is preserved as first published.* --- ## Executive summary The LOKLiK iCraft is sold and marketed as a closed, app-driven cutting machine. Its controller firmware is in fact a **modified build of `Grbl_Esp32`, an open-source CNC firmware licensed under the GNU General Public License, version 3 (GPLv3).** This is not an inference from behavior — the firmware **identifies itself as Grbl_Esp32**, by name and version, in three independent places: 1. On the serial console at power-up: `[MSG:Grbl_ESP32 Ver 1.3a Date 20211103]` 2. In printable strings inside every firmware binary the vendor distributes. 3. By a **character-for-character match** to the upstream Grbl_Esp32 version constants. LOKLiK distributes this GPLv3 software to customers in binary form, inside a product, via a login-gated application — **with no source code, no written offer of source, and no attribution to Grbl_Esp32 or its authors anywhere in the product or marketing.** The firmware also contains a substantial vendor-added modification layer (an `SJConfig` settings subsystem) that is part of the work and is therefore part of the Corresponding Source the GPLv3 requires them to provide. This report documents the evidence and the methodology so that any third party — the copyright holders, the FSF, the Software Freedom Conservancy, or another owner — can reproduce every finding independently. --- ## 1. The device | Property | Value | |---|---| | Product | LOKLiK iCraft cutting machine | | Vendor | LOKLiK Inc. / HTVRONT | | Controller board | Silkscreen `MAIN-CUT-G2 V1.0`, dated `2024-07` (photo: `evidence/board.jpg`) | | MCU | Espressif **ESP32-D0WD-V3**, 8 MB SPI flash | | Flash encryption | **None** (firmware is plaintext and readable) | | Motion | 3 axes (X/Y/Z), Trinamic **TMC2209** stepper drivers over UART | | Vendor tooling | LOKLiK IdeaStudio (login-gated desktop app) + a standalone "FlashTool" updater | The machine was acquired by the author via retail purchase (Amazon, March 2026; order details available to the vendor and to the SFC on request). The author is therefore a lawful recipient of the distributed binary and has standing to request source under GPLv3. --- ## 2. Finding 1 — The firmware is Grbl_Esp32 1.3a (GPLv3) ### 2.1 Primary evidence: the boot banner Connected to the controller's serial port, the firmware announces itself on every boot: ``` [MSG:Grbl_ESP32 Ver 1.3a Date 20211103] [MSG:Compiled with ESP32 SDK:v3.2.3-14-gd3e562907] [MSG:Using machine:LOKLiK_iCraft] [MSG:Axis count 3] [MSG:X Axis motor Trinamic TMC2209 Step:GPIO(19) Dir:GPIO(18) UART1 Rx:GPIO(16) Tx:GPIO(17) Addr:0 ...] [MSG:Y Axis motor Trinamic TMC2209 Step:GPIO(2) Dir:GPIO(4) UART1 ... Addr:1 ...] [MSG:Z Axis motor Trinamic TMC2209 Step:GPIO(33) Dir:GPIO(32) UART1 ... Addr:2 ...] [MSG:X Axis limit switch on pin GPIO(25)] [MSG:Z Axis limit switch on pin GPIO(39)] Grbl 1.3a ['$' for help] [MSG:Ready] ``` (Full serial capture: `evidence/bootlog.png`.) `Grbl_ESP32` is the name of the upstream project. `1.3a` is its version. `20211103` is its build date. `Using machine:` is Grbl_Esp32's own machine-definition mechanism. ### 2.2 Corroborating evidence: strings inside the binaries Every firmware image the vendor distributes (see §3) contains the project's own identifying strings. Representative examples extracted directly from the binary: ``` Grbl_ESP32 Ver %s Date %s Grbl %s ['$' for help] [VER:%s.%s:%s] [OPT: Grbl_Esp32/src/I2SOut.cpp <- upstream source path baked into the binary ) # FW target:grbl-embedded # FW HW: '$H'|'$X' to unlock ``` The string `Grbl_Esp32/src/I2SOut.cpp` is a path from the upstream project's own source tree, embedded by the compiler — direct evidence the binary was built from Grbl_Esp32 source. The build also leaks ESP-IDF / Arduino-ESP32 toolchain paths of the form `/home/runner/work/esp32-arduino-lib-builder/...`, identifying the standard ESP32 build environment used. The firmware's entire configuration system uses Grbl_Esp32's setting-key vocabulary — e.g. `Homing/Feed`, `Homing/Pulloff`, `Spindle/Delay/SpinUp`, `GCode/LaserMode`, `Stepper/IdleTime`, `X/StepsPerMm`. These match the upstream `SettingsDefinitions.cpp` exactly. ### 2.3 Decisive evidence: exact version-constant match The upstream Grbl_Esp32 source (`Grbl_Esp32/src/Grbl.h`) defines: ```c const char* const GRBL_VERSION = "1.3a"; const char* const GRBL_VERSION_BUILD = "20211103"; ``` The LOKLiK device reports `Ver 1.3a Date 20211103`. The version **and** the build-date string are identical, down to the character. This establishes that the LOKLiK firmware was compiled from the upstream Grbl_Esp32 source at that exact version — not an independent or coincidental implementation. ### 2.4 The license Every Grbl_Esp32 source file carries the standard GPL header: > "Grbl is free software: you can redistribute it and/or modify it under the terms of the > GNU General Public License as published by the Free Software Foundation, either version 3 > of the License, or (at your option) any later version." Source: (`Grbl_Esp32/src/Grbl.h`). **Conclusion of Finding 1:** the LOKLiK iCraft firmware is a build of GPLv3-licensed Grbl_Esp32 1.3a. --- ## 3. Finding 2 — It is a *modified* build, distributed in eight versions LOKLiK's standalone FlashTool downloads and stores **eight** firmware versions for this machine (internally labelled `LOKLIK_CRAFTER_2`, versions v01–v08). All eight: - identify as `Grbl_ESP32 Ver 1.3a`, - target the machine definition `LOKLiK_iCraft` / `LK_iCraft`, - and contain a vendor-added settings namespace, **`SJConfig`**, that does **not** exist anywhere in upstream Grbl_Esp32. The `SJ` prefix matches the vendor's software namespace `com.sjtech`, used in their desktop application's data directories — tying the modification to the vendor's own toolchain. ### 3.1 The vendor's modification layer: `SJConfig` These vendor-added settings keys were extracted from the binaries. None appear in the upstream `SettingsDefinitions.cpp`: ``` SJConfig/SN SJConfig/ProductName SJConfig/BlueName SJConfig/BTRATE SJConfig/MateDist SJConfig/MateLoadSpeed SJConfig/PointSet SJConfig/XPulloffDist SJConfig/AxisOffset_X/Y/Z SJConfig/AxisCompens_X/Y SJConfig/LeftPenOffset_X/Y SJConfig/RightPenOffset_X/Y SJConfig/SPSOffset_X/Y ``` These reveal vendor-specific functionality grafted onto the GPL codebase: a stored serial number and product name, Bluetooth naming/rate, dual-tool ("left/right pen") offsets, material-load distance and speed, and per-axis offset and compensation. ### 3.2 The modification is actively maintained and growing Versions v07/v08 expand the `SJConfig` axis-compensation feature from a single value per axis into an **11-point compensation table** per axis (`AxisCompens_X0` … `AxisCompens_X10`, and the same for Y), growing the `SJConfig` key set from 18 keys (v01–v06) to 62 keys (v07–v08). This is ongoing, deliberate development of a derivative work — exactly the kind of modification the GPL requires be released as source. ### 3.3 A note on the v06→v07 size change v01–v06 are ~1.56 MB; v07–v08 drop to ~1.22 MB. A raw byte comparison of the two builds is uninformative (different builds relocate essentially all code). The meaningful, named-symbol difference is the **expansion** of the `SJConfig` calibration subsystem described above — the firmware did not lose vendor features; it gained them. --- ## 4. Finding 3 — Distribution without source, attribution, or offer - **Binary-only distribution.** Firmware reaches customers exclusively through the login-gated LOKLiK IdeaStudio application and the standalone FlashTool updater. No source accompanies the binaries. - **No written offer.** Neither application, nor the product, nor the vendor's website provides the Corresponding Source or a written offer to supply it, as GPLv3 §6 requires for binary distribution. - **No attribution.** The product packaging, the marketing, and the application make no mention of Grbl, Grbl_Esp32, or the GPL. The desktop application *does* ship license notices for various other open-source components it uses — demonstrating the vendor is aware of, and capable of, open-source attribution — yet the GPLv3 firmware that is the machine's actual brain is absent from those notices. The combined effect is that a customer cannot learn the firmware is free software, cannot obtain its source, and is steered to use only the vendor's application. --- ## 5. The obligation under GPLv3 By conveying Grbl_Esp32 (a GPLv3 work) to customers in binary form inside a product, LOKLiK is bound by the GPLv3, including: - **§6 (Conveying Non-Source Forms):** must provide the **Complete Corresponding Source** for the exact binary conveyed — including the modified Grbl_Esp32 sources (the `SJConfig` layer and the `LOKLiK_iCraft` machine definition), and the **scripts and configuration** needed to build and install a working equivalent on the device. - **§5 (Modified Source):** the modified work must itself be licensed GPLv3 and carry appropriate notices. - **§4 / §10:** license and warranty-disclaimer notices must be preserved and conveyed; recipients automatically receive a license from the original licensors. The Corresponding Source obligation runs to **each recipient** of the binary. The author, as a lawful purchaser, is entitled to it. --- ## 6. The ask LOKLiK should come into compliance by releasing the **Complete Corresponding Source for the firmware of the LOKLiK iCraft ecosystem** — all distributed versions (v01–v08 and any successors), including the modified Grbl_Esp32 tree, the `LOKLiK_iCraft` machine definition, the `SJConfig` subsystem, and the build/flash scripts and configuration — under the GPLv3, with proper attribution to the upstream authors. The preferred outcome is cooperative and simple: **publish the source.** It costs the vendor nothing they are entitled to keep, and it is what the license they chose to build on requires. --- ## 7. Methodology — how to reproduce every finding All findings are independently reproducible from a retail device, using only free tools. 1. **Read the firmware** from the ESP32 (no flash encryption is in use): ``` esptool read_flash 0 0x800000 loklik_fw_backup.bin ``` Or obtain the per-version images the vendor's FlashTool downloads to its `resources` directory. 2. **Confirm the image identity and segment layout:** ``` esptool --chip esp32 image-info firmware_v06.bin ``` 3. **Extract identifying strings** (`strings`, or any binary string extractor) and observe the `Grbl_ESP32 Ver`, `LOKLiK_iCraft`, `SJConfig/*`, and `Grbl_Esp32/src/...` strings. 4. **Compare to upstream** at — the version constants in `Grbl.h` and the setting names in `SettingsDefinitions.cpp`. 5. **Read the code** in Ghidra: import as Raw Binary with language `Xtensa:LE:32:default`, lay out the six esptool segments at their load addresses (DROM `0x3f400020`, DRAM `0x3ffbdb60`, IRAM `0x40080000`/`0x40080400`/`0x4008b9c4`, IROM `0x400d0018`), then auto-analyze. The boot-banner and `SJConfig` strings cross-reference directly into the vendor's modified functions. --- ## 8. Evidence appendix ### 8.1 Integrity hashes (SHA-256) of the eight distributed firmware images ``` 2091abe2949bc5a19ba1baebda5dcd7b1173fcbd1af43fe0575b578b2905ca1c firmware_v01.bin (1,562,832 B) 218426d65c6057940f03fd80e165c11d5268fb5c0a94bd209e709a04cef6864d firmware_v02.bin (1,563,824 B) 8648ca52a90fe5c31ac668e3a0f4a3642f40d28c5fea3204c91430a5f801cd53 firmware_v03.bin (1,565,200 B) 8bd858845cdbf8b0d3d6373a674ac2cf4a1a5bcb512af781d88766c10e97ea83 firmware_v04.bin (1,565,232 B) 57d3e4dafdb08fa4652a5e72ea6b4b0575bd0d973527701107d9769a093c07a9 firmware_v05.bin (1,565,664 B) 7a30fc95315b5c442ef9aaf7a37efe65ebf4b058f0d96e0d80512e279bbac23c firmware_v06.bin (1,565,728 B) 0380548b95299aa98e24cf02308924a5d579356a0aa7114c550524db76e97ff1 firmware_v07.bin (1,219,808 B) 9f8d03d1ff7cbee238b5a5ba03f901ddc7a4617fd586e400dbe14eada6cec098 firmware_v08.bin (1,219,744 B) ``` Full-flash readback of the author's own device: ``` da647a9ab5048efef5a252b4060fe4911f79f65180f4f6c1a1df948a43920e73 loklik_fw_backup.bin (8,388,608 B) ``` ### 8.2 esptool image layout (firmware_v06.bin) ``` ESP32 image, version 1, entry 0x400837b0, 6 segments, Chip ID 0 (ESP32) Seg 0 0x3f400020 0x40d90 DROM Seg 1 0x3ffbdb60 0x03884 DRAM Seg 2 0x40080000 0x00400 IRAM Seg 3 0x40080400 0x0b5c4 IRAM Seg 4 0x400d0018 0x11f3a8 IROM (bulk of code) Seg 5 0x4008b9c4 0x0f034 IRAM Validation hash: valid ``` ### 8.3 Per-version identification summary | Version | Size (B) | Grbl ver | Machine | `SJConfig` keys | |---|---|---|---|---| | v01 | 1,562,832 | 1.3a | LOKLiK_iCraft | 18 | | v02 | 1,563,824 | 1.3a | LOKLiK_iCraft | 18 | | v03 | 1,565,200 | 1.3a | LOKLiK_iCraft | 18 | | v04 | 1,565,232 | 1.3a | LOKLiK_iCraft | 18 | | v05 | 1,565,664 | 1.3a | LOKLiK_iCraft | 18 | | v06 | 1,565,728 | 1.3a | LOKLiK_iCraft | 18 | | v07 | 1,219,808 | 1.3a | LOKLiK_iCraft | 62 | | v08 | 1,219,744 | 1.3a | LOKLiK_iCraft | 62 | ### 8.4 Photographic evidence - `evidence/board.jpg` — the controller board (silkscreen `MAIN-CUT-G2 V1.0`, `2024-07`), showing the Espressif ESP32 module and the three Trinamic TMC2209 stepper drivers. - `evidence/bootlog.png` — full serial-console capture of the power-up boot log, including the `Grbl_ESP32 Ver 1.3a Date 20211103` and `Using machine:LOKLiK_iCraft` banner lines. - `evidence/firmware_v01.bin` … `firmware_v08.bin` — the eight distributed firmware images (GPLv3), matching the SHA-256 values in §8.1. - `evidence/ghidra_strings_grbl.png` — Ghidra string listing: the `Grbl_ESP32` banner strings and the leaked `Grbl_Esp32/src/I2SOut.cpp` build path. - `evidence/ghidra_sjconfig.png` — Ghidra strings filtered to `SJConfig`, the vendor-added settings layer. - `evidence/ghidra_path_i2sout.png` — the leaked upstream source path in context. - `evidence/ghidra_decompiler.png` — the firmware open in Ghidra (Xtensa) — listing + decompiler. - `evidence/flashtool_versions.png` — LOKLiK's FlashTool listing versions v01–v08 with update dates (2024-09 through 2026-01). - `evidence/flashtool_models.png` — the FlashTool model picker (Crafter / iCraft / iPaint / iEngrave), showing the shared firmware tooling across the product line. ### 8.5 References - Upstream project: - Version constants: `Grbl_Esp32/src/Grbl.h` → `GRBL_VERSION "1.3a"`, `GRBL_VERSION_BUILD "20211103"` - Stock settings (no `SJConfig`): `Grbl_Esp32/src/SettingsDefinitions.cpp` - Original Grbl: (Sungeon "Sonny" Jeon) - GNU GPL v3: --- *This report concerns software-license compliance. It documents that a GPLv3 work is being distributed in a product, and asks the vendor to meet the obligations of the license they built upon. The author would prefer a cooperative resolution.*