Changelog Generator

A fast, efficient, native CLI tool to automatically generate changelogs from GitHub tags, merged pull requests, and closed issues. Written in Zig

Features

• Fast, compiled binary (zero dependencies, pure Zig stdlib)
• Generates Markdown changelogs automatically
• Groups merged pull requests by labels (Features, Bug Fixes, Merged Pull Requests)
• Adds a Closed Issues section under each release based on issue close timestamps
• Links to PRs, issues, and contributors
• Smart token resolution (--token flag → env vars → gh auth token CLI)
• Works with any GitHub repository
• Progress output during fetch — per-section headers and page counters keep you informed on large repos
• Optional parallel fetching (--parallel <N>) — fetches releases, PRs, and closed issues concurrently; release and PR pagination use bounded page concurrency
• Fully functional core logic verified with integration tests

Building

Requirements: Zig 0.15+

zig build

Usage

Basic Usage

chlogr --repo [org]/[repo]

With Token

chlogr --repo [org]/[repo] --token ghp_xxxxxxxxxxxx

With Parallel Fetching

chlogr --repo [org]/[repo] --parallel 4

Use --parallel <N> on large repositories with many releases, pull requests, and closed issues to fetch all three streams together while letting release and PR pagination use up to N concurrent page requests per stream.

Options

• --repo (required): GitHub repository in the format [Organization or Username]/[Repository name]
• --token (optional): GitHub API token (falls back to env vars or gh CLI)
• --output (optional): Output file path (default: CHANGELOG.md)
• --since-tag (optional): Start from this tag/version
• --until-tag (optional): End at this tag/version
• --exclude-labels (optional): Comma-separated labels to exclude (e.g., duplicate,wontfix)
• --parallel <N> (optional): Fetch releases, pull requests, and closed issues concurrently; release and PR pagination use up to N page requests per stream

Authentication

The tool will attempt to retrieve a GitHub token in this order:

1. --token flag
2. GITHUB_TOKEN environment variable
3. GH_TOKEN environment variable
4. gh auth token command (GitHub CLI)

If none are available, the tool will display a helpful error message.

Example Output

# Changelog

## [Unreleased Changes]

### Features

- New unreleased feature Y (#126) (@dave)

### Bug Fixes

- Unreleased bug fix (#127) (@eve)

### Merged Pull Requests

- Work in progress change (#999) (@developer)

## [v1.2.0](https://github.com/owner/repo/releases/tag/v1.2.0) (2024-01-15)

### Merged Pull Requests

- Update documentation (#125) (@charlie)

### Features

- Add new feature X (#123) (@alice)

### Bug Fixes

- Fix critical bug (#124) (@bob)

### Closed Issues

- Close onboarding issue (#910) (@frank)

## [v1.1.0](https://github.com/owner/repo/releases/tag/v1.1.0) (2024-01-10)

### Closed Issues

- Close docs issue (#911) (@grace)

Development

Running Tests

zig build test

This runs integration tests with mock GitHub data to verify:

• CLI argument parsing (--parallel and all existing flags)
• JSON parsing of releases, PRs, and closed issues
• Changelog grouping and categorization for pull requests and closed issues
• Markdown formatting
• File output

Project Structure

src/
  ├── main.zig                 # Main orchestration logic
  ├── cli.zig                 # CLI argument parsing
  ├── token_resolver.zig      # GitHub token resolution
  ├── models.zig              # Data structures
  ├── http_client.zig         # HTTP client wrapper
  ├── github_api.zig          # GitHub API integration
  ├── changelog_generator.zig # Core changelog logic
  ├── markdown_formatter.zig  # Markdown output formatting
  ├── test_data.zig           # Mock test data
  └── test.zig                # Integration tests

License

MIT