uploadmycode

A browser IDE for Uno boards, built for Chromebook classrooms. A student writes a sketch on a website, the sketch compiles on a small server container running arduino-cli, and the browser flashes the resulting hex onto the board over USB with the Web Serial API. Nothing is installed on the student machine — no IDE, no driver, no extension, no account.

It exists because managed Chromebooks cannot run a desktop IDE, and a class of thirty needs the same tool on every desk in under a minute.

• Uno boards only. The board type is hardcoded server-side; there is no board picker.
• Runs on Cloudflare Workers + Containers. About $5/month plus pennies of usage for one classroom.
• Written and maintained by one teacher. The code is kept boring on purpose.

What it does

• Editor — CodeMirror 6 with C++ highlighting, autocomplete for the common board API, and a library dropdown that inserts the right #include.
• Compile — one POST to the server. Compiler errors come back parsed: a clickable row that jumps to the line, and the offending line highlighted in the editor.
• Upload — the browser flashes the board itself over Web Serial (STK500v1 against the Optiboot bootloader, 115200 baud), with a page-by-page progress bar. Upload is only enabled for hex that was built from the exact text on screen.
• Serial monitor — nine baud rates, autoscroll, timestamps, a send box. It hands the port to the flasher when an upload starts and takes it back afterwards, so a student never has to disconnect anything.
• Sketches — named, autosaved to localStorage, downloadable and importable as .ino. No server-side storage, no student accounts, no PII.
• A rolling class phrase — the teacher sets today's phrase, with an expiry, from a /teacher page guarded by a secret. Nobody compiles without it. Students type it once per tab and it dies with the tab.
• Cost caps — one container instance, scale-to-zero, a per-browser rate limit, a global ceiling, a request-size cap and a compile timeout. All of it so a runaway loop cannot run up a bill overnight.
• Libraries — a fixed allowlist baked into the container image, so a compile never touches the network. Servo, LiquidCrystal, LiquidCrystal I2C and Stepper ship by default.

The live site

https://uploadmycode.com is the author's own instance, for one teacher's classes. It is not a public service: every compile needs that day's class phrase, so the site will look broken to anyone who is not in the room. It is up here as a working reference, not as something to sign up for.

To use this, run your own copy. docs/SETUP.md walks a stranger through it end to end: the supported Cloudflare path, and how to run just the compile server with Docker.

Commands

npm install
npm run typecheck   # tsc --noEmit for the Worker and for web/
npm test            # node --test over test/ (Worker logic) and web/test/ (frontend)
npm run dev:web     # Vite dev server for the editor (proxies /api/compile to localhost:8080)
npm run build       # vite build web -> public/
npm run types       # regenerate worker-configuration.d.ts after editing wrangler.jsonc
npm run deploy      # npm run build, then wrangler deploy (needs Docker running)

wrangler deploy builds container/Dockerfile, so Docker Desktop must be running. npm run dev (wrangler dev) also needs it.

Running the compile server without Docker

container/server.js is the same file the image runs, and it runs directly on Windows. Useful for frontend work: npm run dev:web proxies /api/compile to it. Nothing here is committed: tools/ (/api/format proxies here too; Auto indent needs clang-format on PATH locally — without it only formatting fails, compiles are unaffected.) is gitignored, and the versions must match the pins at the top of container/Dockerfile.

$tools = "$PWD\tools"
New-Item -ItemType Directory -Force $tools | Out-Null

# 1. Pinned arduino-cli (same version as the Dockerfile).
Invoke-WebRequest -Uri 'https://github.com/arduino/arduino-cli/releases/download/v1.5.1/arduino-cli_1.5.1_Windows_64bit.zip' -OutFile "$tools\arduino-cli.zip"
Expand-Archive "$tools\arduino-cli.zip" -DestinationPath "$tools\arduino-cli" -Force

# 2. Keep the toolchain inside tools/ instead of AppData.
$env:PATH = "$tools\arduino-cli;$env:PATH"
$env:ARDUINO_DIRECTORIES_DATA = "$tools\arduino-data"
$env:ARDUINO_DIRECTORIES_USER = "$tools\arduino-user"
$env:ARDUINO_DIRECTORIES_DOWNLOADS = "$tools\arduino-downloads"

# 3. Pinned core and the library allowlist (same versions as the Dockerfile).
arduino-cli core update-index
arduino-cli core install arduino:avr@1.8.8
arduino-cli lib install Servo@1.3.0
arduino-cli lib install LiquidCrystal@1.0.7
arduino-cli lib install "LiquidCrystal I2C@1.1.2"
arduino-cli lib install Stepper@1.1.3

# 4. Serve on http://localhost:8080.
node container/server.js

On any platform, building container/ with Docker gets you the same server and none of that setup: see docs/SETUP.md, Part B.

Docs

• docs/SETUP.md — run your own copy. Start here if this repo is new to you.
• docs/DEPLOY.md — the operator manual for the author's live instance: the daily phrase routine, the teacher key, what guards a compile, adding a library, ALLOWED_CIDRS, cost caps and billing alerts. Most of it applies to any instance.
• PLAN.md — architecture, the locked decisions, and the task list the project was built from. Read it before changing anything structural.
• CREDITS.md — every open-source project this tool is built on, with links, verified licenses, and where to support them.
• docs/CHROMEBOOK-CHECKLIST.md — the Web Serial policy conversation to have with school IT before you rely on any of this, plus a one-Chromebook smoke test.
• docs/T2-TEST.md, docs/T3-TEST.md, docs/T4-TEST.md — manual test scripts for the editor, for flashing a real board, and for the serial monitor. The last two need hardware.

Trademarks and licensing

ARDUINO and UNO are trademarks of Arduino SA. This project is not affiliated with, sponsored by, or endorsed by Arduino SA. "Uno" is used here only to describe which board this software is compatible with.

This repository contains no Arduino software. The container image downloads Arduino's open-source toolchain from official sources at build time — arduino-cli (GPLv3), and the AVR core and its compiler toolchain (GPL/LGPL) — and runs it as a separate program, over a command line, exactly as a user would. Nothing from it is copied into, linked with, or redistributed by this repository. If you build the image, you obtain those components directly from their publishers under their own licenses.

The editor is CodeMirror 6, MIT licensed.

This project's own code is MIT licensed — see LICENSE.

Credits

This is a thin shell around other people's work. CREDITS.md lists every open-source project it stands on — the compiler toolchain the container downloads, the four classroom libraries, CodeMirror, the build tooling, and the protocol documents the flasher was written from — with a link and a verified license for each, and a support link wherever the project publishes one. None of those projects endorses this one; being credited is not affiliation.