Block ads and trackers using the hosts file (2026 guide)

Ads and trackers are ubiquitous on the modern web. While browser extensions like uBlock Origin do an excellent job, the hosts file offers a more radical solution: blocking unwanted domains at the system level, before they even reach your browser.

Why use the hosts file to block?

System-level blocking

Unlike browser extensions that only protect the browser, hosts file blocking works for all applications on your Mac:

• Browsers (Chrome, Safari, Firefox)
• Native applications
• Electron apps
• Games with built-in ads

Advantages over extensions

Performance Extensions analyze each request in real-time. The hosts file blocks before the request is even made.

Privacy No third-party extension has access to your browsing. Blocking is 100% local.

Reliability No extension updates to manage, no conflicts with blocker detectors.

What you can block

• Ads: banners, popups, pre-roll videos
• Trackers: Google Analytics, Facebook Pixel
• Malware: known malicious domains
• Telemetry: data collection by applications
• Crypto-miners: mining scripts

If you're not yet familiar with the hosts file, check out our complete guide to the hosts file first.

How blocking works

When you add an entry like:

0.0.0.0    ads.example.com

You're telling your system: "When someone requests ads.example.com, return address 0.0.0.0 instead of the real IP".

The address 0.0.0.0 is non-routable. The connection fails instantly.

0.0.0.0 vs 127.0.0.1

0.0.0.0 (recommended)

• Fails immediately
• No connection attempt
• Faster

127.0.0.1 (localhost)

• Attempts a local connection
• Can create a delay

The best blocklists

Steven Black's Hosts (Recommended)

The reference for consolidated hosts lists.

URL: github.com/StevenBlack/hosts

Contents:

• Base version: ~60,000 domains (ads + malware)
• Extended versions available
• Regularly updated

Other popular lists

Dan Pollock's hosts

• URL: someonewhocares.org/hosts/
• About 14,000 domains
• Maintained for 20+ years

Energized Protection

• URL: github.com/EnergizedProtection/block
• Ultra-complete versions (up to 1M+ domains)

Setting up a blocklist

Manual method

1. Download the list

curl -o ~/Downloads/hosts https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts

2. Back up your current hosts file

sudo cp /etc/hosts /etc/hosts.backup

3. Merge the files

cat /etc/hosts.backup ~/Downloads/hosts | sudo tee /etc/hosts > /dev/null

4. Flush DNS cache

sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

For more details on DNS flushing, check our complete guide to flushing DNS on Mac.

With Locahl

1. Download the list 2. Use the import function 3. Enable/disable individually 4. Automatic DNS flush

Handling false positives

Aggressive blocking can sometimes break legitimate sites.

Common symptoms

• Images not loading
• Login buttons not working
• Videos not playing
• Payment errors

Identifying the problematic domain

1. Open DevTools (F12 or Cmd+Option+I) 2. "Network" tab 3. Filter by "blocked" or look for errors

Unblocking a domain

In the hosts file, comment out the line:

# 0.0.0.0    necessary-domain.com

Optimization for large lists

Automatic update script

#!/bin/bash
BACKUP=/etc/hosts.custom
BLOCKLIST=https://raw.githubusercontent.com/StevenBlack/hosts/master/hosts

# Save custom entries
sudo head -50 /etc/hosts > $BACKUP

# Download and merge
curl -s $BLOCKLIST | cat $BACKUP - | sudo tee /etc/hosts > /dev/null

# Flush DNS
sudo dscacheutil -flushcache && sudo killall -HUP mDNSResponder

echo "Hosts file updated!"

Blocking limitations

What it doesn't block

First-party ads Ads served from the same domain as content (e.g., YouTube) can't be blocked without blocking the entire service.

Dynamic content Constantly changing domains can escape blocking.

Recommended complements

• Pi-hole: Filtering DNS for your entire network
• Little Snitch: Application firewall for Mac
• NextDNS: Cloud filtering DNS

Specific use cases

Basic parental control

0.0.0.0    facebook.com
0.0.0.0    www.facebook.com
0.0.0.0    instagram.com
0.0.0.0    tiktok.com

Focused work environment

0.0.0.0    twitter.com
0.0.0.0    reddit.com
0.0.0.0    youtube.com

Block telemetry

0.0.0.0    telemetry.microsoft.com
0.0.0.0    ic.adobe.io

Conclusion

The hosts file is a powerful tool for blocking ads, trackers, and malicious domains at system level. While more modern solutions exist (Pi-hole, NextDNS), the simplicity of the hosts file makes it an effective first line of defense.

For comfortable management of these thousands of entries, a tool like Locahl lets you import lists and enable/disable individual blocks.