Open-Source VPNs - Transparent & Verifiable
Open-source VPNs let anyone inspect the code for backdoors and hidden logging. See which providers are open source, which are audited, and why it matters.
What "Open Source" Means for a VPN
An open-source VPN publishes the source code for its apps (and sometimes its protocol) so anyone can read it. Instead of trusting a company's claims about encryption and logging, security researchers - and you - can inspect exactly what the software does. It's the difference between a sealed box and a glass one.
Why It Matters
- No hidden logging: reviewers can confirm the app isn't quietly recording activity
- No backdoors: the code can't secretly phone home or weaken encryption without someone noticing
- Verifiable encryption: the community can check the crypto is implemented correctly
- Faster bug fixes: more eyes on the code means vulnerabilities get caught and patched
Open source shifts trust from marketing to math. It's most powerful when paired with independent audits - the code says what the app should do, and the audit verifies the running infrastructure matches.
Open-Source VPNs
| Provider | Open Source | Audited By | Jurisdiction | Privacy Score |
|---|---|---|---|---|
| Mullvad | Yes Yes | Cure53, Assured, Radically Open Security | Sweden | 9.7/10 |
| ProtonVPN | Yes Yes | Securitum | Switzerland | 9.6/10 |
| IVPN | Yes Yes | Cure53 | Gibraltar | 9.4/10 |
| ExpressVPN | Yes Yes | KPMG, PricewaterhouseCoopers, Cure53 | British Virgin Islands | 9.4/10 |
| Private Internet Access | Yes Yes | Deloitte | United States | 8.5/10 |
| Windscribe | Yes Yes | Cure53 | Canada | 8.3/10 |
| Mozilla VPN | Yes Yes | Cure53 | United States | 8/10 |
ProtonVPN - Fully Open Source + Swiss
Every ProtonVPN app is open source and audited by Securitum. Combined with Switzerland's strong privacy laws, it earns the highest privacy score in our lineup (9.6/10). If verifiable transparency is your priority, this is the benchmark.
PIA - Open Source + Court-Proven
Private Internet Access publishes fully open-source apps on GitHub and, uniquely, has proven its no-log policy in court when subpoenaed by the FBI. Despite US jurisdiction, that real-world test is stronger evidence than most audits.
ExpressVPN - Open-Source Protocol
ExpressVPN open-sourced its Lightway protocol so the community can audit the core of its VPN connection, and Cure53 has reviewed it. The apps themselves aren't fully open source, but open-sourcing the protocol is a meaningful step.
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Closed-Source (But Audited) VPNs
Closed source doesn't mean untrustworthy. These providers keep their app code private but submit to independent audits, which verify their no-log and security claims:
| Provider | Open Source | Audited By | Privacy Score |
|---|---|---|---|
| NordVPN | No Closed | Deloitte, PricewaterhouseCoopers | 9.5/10 |
| Surfshark | No Closed | Deloitte, Cure53 | 8.7/10 |
| CyberGhost | No Closed | Deloitte | 8.6/10 |
| hide.me | No Closed | DefenseCode | 8.2/10 |
| VyprVPN | No Closed | Leviathan Security | 8.1/10 |
| PrivadoVPN | No Closed | 8/10 | |
| TunnelBear | No Closed | Cure53 | 7.9/10 |
| PureVPN | No Closed | KPMG, Altius IT | 7.8/10 |
| IPVanish | No Closed | Leviathan Security | 7.6/10 |
| ZoogVPN | No Closed | 7.5/10 | |
| FastestVPN | No Closed | Altius IT | 7.4/10 |
| StrongVPN | No Closed | 7.2/10 | |
| Hotspot Shield | No Closed | AV-TEST | 6.8/10 |
NordVPN is the standout here - closed source, but with the most extensive audit history in the industry (Deloitte and PwC) and a 9.5/10 privacy score, just behind the open-source leaders.
Our Verdict
For maximum transparency, choose an open-source VPN with independent audits: ProtonVPN (fully open, Swiss) or PIA (fully open, court-proven). If you prioritize speed and streaming and are comfortable relying on strong audits instead, NordVPN remains an excellent, well-verified choice. Open source is a powerful trust signal - but pair it with audits, and weigh it against your other priorities.