GitHub - redraw/rapel: chunked resumable downloads in unstable networks

Chunked HTTP downloader with resume support.

A modern, cross-platform implementation with improved state management and progress tracking.

Installation

Or install directly:

go install github.com/redraw/rapel@latest

Usage

Download a file with default settings (100MB chunks, 1 concurrent job):

rapel download https://example.com/file.bin

Download with custom chunk size and multiple concurrent downloads:

rapel download https://example.com/file.bin -c 50M --jobs 4

Download through a proxy:

rapel download https://example.com/file.bin -x socks5h://127.0.0.1:9050

Download and auto-merge:

rapel download https://example.com/file.bin --merge

Run command after each chunk completes:

rapel download https://example.com/file.bin --post-part 'rclone move {part} remote:bucket/'

Merge chunk files manually:

rapel merge                                    # Auto-detects output name
rapel merge --pattern 'file.*.part'           # Auto-detects as "file"
rapel merge -o output.bin --delete            # Explicit name, delete after merge

Features

JSON state management: Single .rapel-state.json file tracks all chunk metadata
Graceful shutdown: Ctrl+C saves progress and allows resume
Better progress display: Real-time speed, completion status with ANSI formatting
Cross-platform: Works on Linux (amd64, arm64, arm v6/v7), macOS (Intel/Apple Silicon), Windows, and FreeBSD
Raspberry Pi support: Native ARM v7 and v6 binaries for all Raspberry Pi models
Resume support: Automatically resumes interrupted downloads
Concurrent downloads: Download multiple chunks simultaneously
Post-part hooks: Run custom commands after each chunk completes (e.g., upload to cloud)
Smart merging: Auto-detects output filename and handles multiple download sessions

Options

Download command:

-c SIZE          Chunk size (K, M, G suffix). Default: 100M
-x URL           Proxy URL (e.g., socks5h://127.0.0.1:9050)
-r N             Retries per request. Default: 10
--no-head        Skip HEAD request (requires --size)
--size BYTES     Total size in bytes (required if --no-head)
--jobs N         Concurrent chunks. Default: 1
--force          Force re-download even if state exists
--merge          Merge chunks after download (auto-detects output name)
--post-part CMD  Command to run after each part completes
                 Placeholders: {part} {idx} {base}

Merge command:

-o FILE        Output filename (auto-detected if not provided)
--pattern GLOB Pattern for chunk files. Default: *.part
--delete       Delete chunk files after merging