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Cheap Yellow Monster · NM-CYD-C5 · Classic CYD · WS-C5-28
Web Serial flasher powered by esptool-js. Select your board, then flash firmware directly from your browser — no software install required.
Control
Channel
Board
Ready to connect.
Erase does a full flash erase before writing the images. Use it only when recovering from bad partitions, bootloops, or stale NVS config. Normal updates do not need it.
Serial monitor
Independent UART terminal mode for reading and writing serial data directly from the browser.
Monitor disconnected.
Release info
Loading manifest.
- ROM mode: hold BOOT, plug the board in via USB-C, then release BOOT.
- Close serial hogs: quit any terminal monitors or apps holding the COM port before connecting.
- Stuck? Unplug, click Connect, then plug in again while holding BOOT.
- After flash: press RESET if the board does not auto-reboot. Insert a FAT32 MicroSD card (≤ 32 GB) before booting.
- Power: use a clean 5 V USB supply rated ≥ 500 mA. Undervoltage is the most common cause of reset loops during WiFi scanning.
Direct downloads
Same binaries used by this flasher.
Browser support
Chrome or Edge on desktop over HTTPS. Web Serial is required for both flashing and monitor mode. Firefox and Safari are not supported.
Support this project
If you find this toolkit useful and would like to support its continued development, consider buying the developer a coffee!