Open-source VPN software
Besides WireGuard and OpenVPN, the following are some of the most widely-known and commonly used open-source VPN protocols or implementations (roughly ranked by real-world relevance).
Think of this as a “map” of the open-source VPN ecosystem: legacy enterprise-grade standards, corporate compatibility layers, and the newer overlay networks that replace parts of traditional VPN usage.
Top tier (modern mainstream)
1. WireGuard®
- Why it matters: minimal, fast, and modern cryptography; widely adopted
- Best for: mobile usage, roaming networks, modern consumer VPNs
2. OpenVPN
- Why it matters: long-standing, flexible, very mature ecosystem
- Best for: enterprise compatibility, complex network requirements
Top tier (legacy but still widely used)
1️⃣ IPsec (strongSwan / Libreswan)
- Open-source: fully open-source implementations
- Background: long history; widely used in enterprise, government, and router deployments
- Common implementations: strongSwan (most popular), Libreswan
⚠️ Downsides
- Complex configuration
- Average UX under NAT and mobile networks
One-line take
A “proper” engineering standard, but not friendly for typical consumers
2️⃣ SoftEther VPN
- License: GPL
- Origin: developed at the University of Tsukuba (Japan)
- Multi-protocol support: its own protocol, OpenVPN, L2TP/IPsec, SSTP
- Known for: strong traversal capability; once very popular in academia and related communities
One-line take
A “Swiss army knife” VPN, but with a heavier architecture
Second tier (famous in specific circles)
3️⃣ OpenConnect
- Purpose: started as a compatible alternative to Cisco AnyConnect
- Later support: Palo Alto GlobalProtect, Fortinet, and more
- Focus: enterprise VPN compatibility, not consumer-grade usage
One-line take
A powerful compatibility replacement for enterprise VPN clients
4️⃣ Tinc
- Type: Mesh VPN (peer-to-peer)
- Common use: multi-datacenter networking, internal connectivity
- Emphasis: networking/overlay rather than “bypass” usage
One-line take
A favorite among ops and network engineers
New era: “beyond VPN” overlays (very important)
5️⃣ Nebula (by Slack)
- Type: overlay network for zero-trust style connectivity
- Note: not a classic VPN, but replacing parts of VPN use cases
- Comparable to: Tailscale, ZeroTier
One-line take
A next-generation shape of “VPN-like” networking
6️⃣ ZeroTier (core open-source)
- Open-source: core protocol is open-source (commercially operated)
- Form: P2P virtual LAN
- Known for: extremely easy setup and usage
One-line take
Not quite a VPN, but often more usable than a VPN
One-sentence summary
The only open-source VPN technologies historically recognized on the same “tier” as WireGuard / OpenVPN are IPsec (strongSwan) and SoftEther.
The rest are either enterprise compatibility replacements or the newer generation of post-VPN overlay networking tools.