nlang

A build system for executable extensions — files with double extensions (like .html.md, .css.md, .json.js) that get executed at build time to produce their output files.

Write your site content as LLM prompts or JavaScript, and nlang builds it into static files.

How it works

If a file has more than one extension, nlang treats it as executable:

• .md executor — The file contains an LLM prompt. The response becomes the output file.

  • index.html.md → prompts an LLM → produces index.html
  • styles.css.md → prompts an LLM → produces styles.css
  • about.md.md → prompts an LLM → produces about.md

• .js / .ts executor — The file is a script whose output becomes the result.

  • data.json.js → runs the script → produces data.json

Features

• Dependency graph — Files can reference each other with @{path}. nlang scans all files, resolves dependencies, and executes in parallel where possible.
• Dynamic routes — Use bracket notation for parameterized paths: blog/[name].html.md with a corresponding blog/name.json providing the available values.
• Frontmatter config — Configure model, MCP servers, and other options per-file via YAML frontmatter.
• Cron triggers — Set trigger: {cron-expression} in frontmatter to schedule rebuilds.
• Caching — Built-in LLM response cache with configurable TTL to avoid redundant API calls.
• CI/CD integration — nlang init generates a GitHub Actions workflow for automatic builds.

Install

npm install -g nlang-cli

Requires Node.js >= 18.

Usage

# Generate a GitHub Actions workflow for your repo
nlang init

# Build all executable files in the current directory
nlang build

# Build a specific file (and its dependencies)
nlang build -f index.html.md

# Preview what would be executed
nlang build --dry-run

# Build from a specific directory
nlang build -d ./my-site

Project config

Add an nlang.json to your project root (or any subdirectory — more specific configs take priority):

{
  "model": "gpt-5.4-2026-03-05",
  "out": "dist"
}

Example

my-site/
  nlang.json
  index.html.md        # LLM prompt → index.html
  styles.css.md        # LLM prompt → styles.css
  about.md.md          # LLM prompt → about.md
  blog/
    [name].html.md     # Dynamic route template
    name.json           # ["hello-world", "second-post"]
  data/
    stats.json.md      # LLM prompt → stats.json
  dist/                 # Build output

License

MIT