codeink

Self-hostable web app that converts plaintext code into syntax-highlighted rich text, optimized for pasting into Microsoft Outlook with formatting preserved.

Outlook strips CSS classes from pasted HTML. codeink solves this by walking the rendered DOM, reading getComputedStyle() for every element, and baking the resolved colors and font weights into inline style="" attributes before writing to the clipboard.

Features

• 40+ languages via a vendored copy of highlight.js (no CDN, no external requests)
• 12 themes (dark and light)
• Auto-detect language mode
• Live split-pane preview
• Optional line numbers
• Keyboard shortcuts: Ctrl+Enter / Cmd+Enter to copy, Tab to indent
• Works offline (PWA with service worker)
• No build step — plain HTML/CSS/JS

Quick Start

Docker (recommended)

docker compose up --build
# http://localhost:8080

Pull from GHCR

docker pull ghcr.io/neckbeardprince/codeink:latest
docker run -p 8080:8080 ghcr.io/neckbeardprince/codeink:latest

The image is based on nginx-unprivileged and runs as a non-root user on port 8080.

Local dev (no Docker)

go run main.go
# http://localhost:8080

GitHub Pages

The app is entirely client-side, so it can also be hosted on GitHub Pages. The included pages.yml workflow deploys automatically on push to main.

How It Works

1. You paste code into the left pane
2. highlight.js renders syntax-highlighted HTML in the right pane
3. When you click Copy as Rich Text:
   • inlineStyles() clones the highlighted DOM and walks every node
   • For each <span>, it reads getComputedStyle() and writes color, font-weight, font-style, and text-decoration as inline styles
   • resolveBackground() walks up the DOM tree to find the actual background color (different themes set it on different elements)
   • The result is wrapped in a <pre> with inline styles and written to the clipboard as text/html
4. Paste into Outlook — formatting is preserved

Adding Languages or Themes

Languages: Add the language to the LANGUAGES list in scripts/update-hljs.sh, re-run the script, then add a <script> tag in index.html for the vendored language pack and a corresponding <option> in the language <select>.

Themes: Add the theme to the THEMES list in scripts/update-hljs.sh, re-run the script, then add an <option> in the theme <select> in index.html and a path entry in THEME_PATH in app.js. If the theme is dark, add its value to the DARK_THEMES set in app.js.

Updating highlight.js

highlight.js is vendored under static/vendor/highlight.js/<version>/ so the app makes zero external requests:

scripts/update-hljs.sh 11.11.1   # downloads, updates references, removes old versions

Project Structure

Dockerfile              # nginx-unprivileged (non-root), serves static files
docker-compose.yml      # One-command startup (host 8080 -> container 8080)
nginx.conf              # gzip, caching, security header includes
security-headers.conf   # Shared security headers incl. Content-Security-Policy
main.go                 # Go HTTP server for local dev (binds 127.0.0.1)
go.mod                  # Go module
scripts/
  update-hljs.sh        # Re-vendor highlight.js at a given version
static/
  index.html            # Single-page app
  style.css             # Dark UI theme, responsive grid layout
  app.js                # Highlighting, inline style resolution, clipboard copy
  favicon.svg           # SVG favicon (code brackets + ink drop)
  manifest.json         # PWA manifest
  sw.js                 # Service worker for offline support
  vendor/highlight.js/  # Vendored highlight.js core, languages, and themes
.github/
  workflows/
    docker-publish.yml  # Build + push to GHCR on push/tag
    ci.yml              # Docker smoke test, security header + vendored asset checks
    pages.yml           # Deploy to GitHub Pages
renovate.json           # Automated dependency updates

License

MIT