Reputable ad blockers — especially open-source ones — are safe to install. The question worth asking is not whether ad blockers in general are safe, but whether the specific ad blocker you’re considering is trustworthy. The wrong choice can expose you to an extension that is worse than the ads it claims to block.
What Permissions Do Ad Blockers Need?
Most ad blockers request the permission “Read and change all your data on all websites.” This sounds alarming, but it is required for any extension that needs to see and modify outgoing network requests — which is exactly what ad blocking requires. Without this permission, an extension cannot intercept requests to ad servers.
Having the permission does not mean the extension uses it to read your data. An open-source ad blocker with this permission that makes no external calls (other than downloading filter lists) is verifiably not collecting your data — you can confirm this by reading the code.
How to Evaluate an Ad Blocker’s Safety
1. Is it open source?
Open-source extensions can be audited by anyone. If an extension claims to not collect data, you can verify that claim by reading the code. Closed-source extensions require you to trust the company’s word.
ProBlocker is fully open source: github.com/theproblocker/adblocker
uBlock Origin is fully open source. AdBlock and Adblock Plus are not.
2. Does it have a history of incidents?
Search for the extension name along with “security” or “data collection” to check if there are documented issues. Some extensions have been caught injecting affiliate links or sending browsing data to third parties.
3. Who owns it?
AdBlock (not Adblock Plus) was acquired by Eyeo GmbH — the same company that runs the Acceptable Ads program. Both AdBlock and Adblock Plus now share the Acceptable Ads whitelist. Ownership and business model matter for evaluating long-term trust.
4. Does it have Acceptable Ads?
Acceptable Ads is not a security issue, but it is a transparency issue. An ad blocker that accepts payment from advertisers to allow their ads through has a financial relationship with the ad ecosystem it claims to block. Some users find this acceptable; others do not.
Ad blockers without Acceptable Ads →
Known Safe Ad Blockers
| Ad blocker | Open source | Data collection | Acceptable Ads |
|---|---|---|---|
| ProBlocker | Yes | None (verifiable) | No |
| uBlock Origin | Yes | None (verifiable) | No |
| AdGuard | Partial | Limited (stated) | Yes (default) |
| AdBlock | No | Unverifiable | Yes (default) |
| Adblock Plus | No | Unverifiable | Yes (default) |
What Makes an Ad Blocker Unsafe?
Red flags to watch for:
- Not available in an official browser store (Chrome Web Store, Firefox Add-ons)
- Very few reviews or recently published with no track record
- Requests permissions unrelated to ad blocking (access to clipboard, camera, microphone)
- Closed source with no transparency report
- Name that closely mimics a well-known ad blocker (e.g., “AdBlock Pro”, “uBlock Plus”)
ProBlocker Safety Summary
ProBlocker is open source, so claims about data collection can be verified by anyone reading the code. It requests the standard extension permission required for ad blocking. It makes no external calls during normal use except filter list downloads. It does not collect browsing history, IP addresses, search queries, or any personal data.
Read ProBlocker’s full transparency report →