Axel

Overview

Axel is a lightweight command-line download accelerator that improves download speeds by using multiple simultaneous connections to retrieve files. It supports HTTP, HTTPS, and FTP protocols and works across Linux, macOS, and Windows platforms. Axel is particularly useful for downloading large files over slow or unstable connections.

Installation

Linux (Debian/Ubuntu)

sudo apt-get update
sudo apt-get install axel

Linux (Fedora/RHEL)

sudo dnf install axel

macOS

brew install axel

Linux (Alpine)

apk add axel

From Source

git clone https://github.com/axel-download-accelerator/axel.git
cd axel
./configure
make
sudo make install

Basic Usage

Command	Description
axel URL	Download file using default settings (4 connections)
axel -o filename URL	Download and save with custom filename
axel -n 8 URL	Use 8 simultaneous connections
axel --help	Display help and available options
axel --version	Show Axel version information

Connection Management

Multiple Connections

# Download with 8 connections (faster for large files)
axel -n 8 https://example.com/largefile.iso

# Use 12 connections for maximum speed
axel -n 12 https://example.com/video.mp4

# Single connection mode (useful for unstable servers)
axel -n 1 https://example.com/file.zip

Connection Control

# Set number of connections and search for mirrors
axel -n 10 -S 4 https://example.com/download.tar.gz

# Verbose output showing connection details
axel -v https://example.com/file.bin

# Quiet mode (minimal output)
axel -q https://example.com/package.tar.gz

Output and File Naming

Custom Output Filenames

# Save with specific filename
axel -o myfile.zip https://example.com/download

# Save to specific directory
axel -o /tmp/downloads/file.iso https://example.com/file.iso

# Download multiple files to same directory
axel -o /downloads/ https://example.com/file1.zip
axel -o /downloads/ https://example.com/file2.zip

Progress Display

# Default progress bar with speed and ETA
axel https://example.com/file.tar.gz

# Verbose mode with detailed connection information
axel -v https://example.com/largefile.bin

# Very verbose with debug information
axel -vv https://example.com/download.tar.bz2

Bandwidth Management

Limiting Download Speed

# Limit bandwidth to 1 MB/s
axel -s 1048576 https://example.com/file.zip

# Limit to 500 KB/s (useful for avoiding bandwidth throttling)
axel -s 512000 https://example.com/video.mp4

# Limit to 100 KB/s for background downloads
axel -s 102400 https://example.com/package.tar.gz

Adaptive Speed Control

# Start with 10 connections but limit speed
axel -n 10 -s 2097152 https://example.com/large.iso

# Adjust connections dynamically for stability
axel -n 8 -s 5242880 https://example.com/download.tar.gz

HTTP Headers and Authentication

Custom Headers

# Add User-Agent header for compatibility
axel -H "User-Agent: Mozilla/5.0" https://example.com/file.zip

# Multiple custom headers
axel -H "User-Agent: Mozilla/5.0" -H "Accept-Language: en-US" https://example.com/download

# Referer header for hotlink protection
axel -H "Referer: https://example.com/downloads" https://cdn.example.com/file.tar.gz

Authentication

# Basic HTTP authentication
axel -a username:password https://example.com/secured-file.zip

# Download from private repository
axel -a user:token https://api.github.com/repos/user/repo/releases/download/v1.0/app.tar.gz

Proxy Support

HTTP/HTTPS Proxy

# Download through HTTP proxy
axel -p http://proxy.example.com:8080 https://example.com/file.zip

# Proxy with authentication
axel -p username:password@proxy.example.com:8080 https://example.com/download

# HTTPS proxy
axel -p https://proxy.example.com:8443 https://example.com/largefile.iso

Environment Variables

# Set proxy via environment variable
export http_proxy=http://proxy.example.com:8080
axel https://example.com/file.zip

# Set proxy for HTTPS
export https_proxy=http://proxy.example.com:8080
axel https://secure.example.com/file.tar.gz

# Unset proxy
unset http_proxy https_proxy

Resume Downloads

Resuming Interrupted Downloads

# Resume incomplete download
axel https://example.com/largefile.iso

# Axel automatically detects partial files and resumes
# If download was interrupted, run same command again

# Force resume even if file seems complete
axel -a https://example.com/file.zip

Cleanup Partial Downloads

# Remove partial download and restart fresh
rm largefile.iso.st
axel https://example.com/largefile.iso

# List partial downloads in current directory
ls -la *.st

# Remove all partial downloads
rm *.st

Advanced Usage

Configuration Files

# Axel reads config from ~/.axelrc
cat ~/.axelrc

# Set default number of connections
# In ~/.axelrc: num_connections=8

# Set default output directory
# In ~/.axelrc: outdir=/home/user/downloads

Batch Downloads

# Create file list
cat > downloads.txt << EOF
https://example.com/file1.zip
https://example.com/file2.tar.gz
https://example.com/file3.iso
EOF

# Download all files
while read url; do
    axel -n 8 "$url"
done < downloads.txt

Combining Options

# Maximum speed with 12 connections, custom filename, verbose output
axel -n 12 -o /tmp/download.zip -v https://example.com/file.zip

# Bandwidth limited, authenticated, through proxy with custom header
axel -n 8 -s 1048576 -a user:pass -p proxy:8080 \
  -H "Referer: https://example.com" https://example.com/secure-download.tar.gz

Comparison with Other Tools

Axel vs wget

# wget - single connection, simple
wget https://example.com/file.zip

# axel - multi-connection, faster
axel https://example.com/file.zip

# axel typically 2-4x faster for large files

Axel vs curl

# curl - primarily for APIs and single transfers
curl -O https://example.com/file.zip

# axel - optimized for large file downloads
axel https://example.com/file.zip

Axel vs aria2

# aria2 - more features, steeper learning curve
aria2c -x 16 https://example.com/file.zip

# axel - simpler syntax, lightweight
axel -n 16 https://example.com/file.zip

Practical Examples

Download Large ISO Files

# Download Linux distribution ISO with 10 connections
axel -n 10 https://releases.ubuntu.com/22.04/ubuntu-22.04-desktop-amd64.iso

# Download and verify
sha256sum ubuntu-22.04-desktop-amd64.iso

Background Download with Speed Limiting

# Limit bandwidth to avoid network congestion
axel -n 6 -s 2097152 https://example.com/largefile.tar.gz &

# Check progress in background
jobs

Resume Failed Download

# Initial attempt
axel -n 8 https://example.com/software.bin

# Connection dropped? Simply re-run the same command
# Axel detects the partial file and resumes automatically
axel -n 8 https://example.com/software.bin

Download from Mirror Sites

# Download with fallback sources
axel -n 8 https://primary-mirror.example.com/file.zip

# If primary fails, manually try mirror
axel -n 8 https://backup-mirror.example.com/file.zip

Troubleshooting

Connection Refused

# Server may block multiple connections
axel -n 1 https://example.com/file.zip

# Try with fewer connections
axel -n 4 https://example.com/file.zip

Slow Downloads

# Verify bandwidth isn't limited
axel -v https://example.com/file.zip

# Try increasing connections
axel -n 16 https://example.com/file.zip

# Check network conditions
ping example.com

File Already Exists

# Axel won't overwrite; rename or remove existing file
rm existingfile.zip
axel https://example.com/file.zip

# Or save with different name
axel -o file-new.zip https://example.com/file.zip

Tips and Tricks

Speed up Downloads Across Networks

# Optimal settings for most scenarios
axel -n 8 -H "User-Agent: Mozilla/5.0" https://example.com/file.zip

Monitor Download in Real-time

# Use watch command to monitor file size
watch -n 1 'ls -lh largefile.iso'

# In another terminal, run axel
axel -n 8 https://example.com/largefile.iso

Save Bandwidth with Partial Downloads

# Stop download with Ctrl+C
axel https://example.com/largefile.tar.gz
# Press Ctrl+C to interrupt

# Resume continues from where it stopped
axel https://example.com/largefile.tar.gz