* [frp](https://github.com/fatedier/frp) [](https://github.com/fatedier/frp/stargazers) - Comprehensive open alternative to ngrok. Supports UDP, and has a P2P mode. I believe it uses a custom TCP protocol for multiplexing, which can either run over a single TCP connection or a connection pool.
* [ngrok 1.0](https://github.com/inconshreveable/ngrok) [](https://github.com/inconshreveable/ngrok/stargazers) - Original version of ngrok. No longer developed in favor of the commercial 2.0 version.
* [localtunnel](https://github.com/localtunnel) [](https://github.com/localtunnel/localtunnel/stargazers) - Written in node. Popular suggestion.
* [Teleport](https://goteleport.com/) [](https://github.com/gravitational/teleport) - Comprehesive control plane tool, but also supports [accessing apps](https://goteleport.com/docs/application-access/introduction/) behind NATs. Written in Go.
* [Nebula](https://github.com/slackhq/nebula) - [](https://github.com/zerotier/slackhq/nebula) Peer-to-peer overlay network. Developed and used internally by Slack. Similar to Tailscale but completely open source. Doesn't use WireGuard. Written in Go.
* [ZeroTier](https://www.zerotier.com/) - [](https://github.com/zerotier/ZeroTierOne/stargazers) Layer 2 overlay network. They take decentralization seriously, and like to say "decentralize until it hurts, then centralize until it works." Written in C++.
* [sshuttle](https://github.com/sshuttle/sshuttle) [](https://github.com/sshuttle/sshuttle/stargazers) - Open source project originally from one of the founders of Tailscale. Server doesn't require root; client does. Explicitly designed to avoid TCP-over-TCP issues.
* [chisel](https://github.com/jpillora/chisel) [](https://github.com/jpillora/chisel/stargazers) - SSH under the hood, but still uses a custom client binary. Supports auto certs from LetsEncrypt. Written in Go.
* [bore](https://github.com/ekzhang/bore) [](https://github.com/ekzhang/bore/stargazers) - Minimal tunneling solution. MIT Licensed. Written in Rust.
* [expose](https://github.com/beyondcode/expose) [](https://github.com/beyondcode/expose/stargazers) - ngrok alternative written in PHP.
* [rathole](https://github.com/rapiz1/rathole) [](https://github.com/rapiz1/rathole/stargazers) - Similar to frp, including the config format, but with improved performance. Low resource consumption. Hot reload. Written in Rust.
* [go-http-tunnel](https://github.com/mmatczuk/go-http-tunnel) [](https://github.com/mmatczuk/go-http-tunnel/stargazers) - Uses a single HTTP/2 connection for muxing. Need to manually generate certs for server and clients.
* [sish](https://github.com/antoniomika/sish) [](https://github.com/antoniomika/sish/stargazers) - Open source ngrok/serveo alternative. SSH-based but uses a custom server written in Go. Supports WebSocket tunneling.
* [tunnelto](https://tunnelto.dev/) [](https://github.com/agrinman/tunnelto/stargazers) - Open source (MIT). Written in Rust.
* [wstunnel](https://github.com/erebe/wstunnel) [](https://github.com/erebe/wstunnel/stargazers) - Proxies over WebSockets. Focus on proxying from behind networks that block certain protocols. Written in Haskell with executables provided.
* [OpenZiti](https://openziti.github.io) - [](https://github.com/openziti/ziti/stargazers) - Overlay network. The goal of OpenZiti is to extend zero trust all the way into your application, not just to your network. Apache 2.0 license. Written in Go.
* [Crowbar](https://github.com/q3k/crowbar) [](https://github.com/q3k/crowbar/stargazers) - Tunnels TCP connections over HTTP GET and POST requests.
* [boringproxy](https://boringproxy.io/) [](https://github.com/boringproxy/boringproxy/stargazers) - Designed to be very easy to use. No config files. Clients can be remote-controlled through a simple WebUI and/or REST API on the server.
* [tunneller](https://github.com/skx/tunneller) [](https://github.com/skx/tunneller/stargazers) - Open source. Written in Go.
* [jprq](https://github.com/azimjohn/jprq) [](https://github.com/azimjohn/jprq/stargazers) - Proxies over WebSockets. Written in Python.
* [tunnel](https://github.com/koding/tunnel) [](https://github.com/koding/tunnel/stargazers) - This one is a Golang library, not a program you can just run. However, it looks easy to use for creating custom solutions. Uses a single TCP socket, and [yamux](https://github.com/hashicorp/yamux) for multiplexing.
* [pgrok](https://www.proxy.jetzt/) [](https://github.com/jerson/pgrok/stargazers) - Fork of ngrok 1.0, with more recent commits.
* [SirTunnel](https://github.com/anderspitman/SirTunnel) [](https://github.com/anderspitman/SirTunnel/stargazers) - Minimal, self-hosted, 0-config alternative to ngrok. Similar to sish but leverages Caddy+OpenSSH rather than custom server code.
* [remotemoe](https://github.com/fasmide/remotemoe) [](https://github.com/fasmide/remotemoe/stargazers) - SSH-based, with custom golang server. Does some cool unique things. Instead of just plain tunnels, it drops you into a basic CLI UI that offers several useful commands interactively, such as adding a custom hostname. Also allows end-to-end encryption for both HTTPS and upstream SSH. Doesn't appear to offer non-e2e HTTPS, ie no auto Let's Encrypt support.
* [StaqLab Tunnel](https://tunnel.staqlab.com/) [](https://github.com/abhishekq61/tunnel-client/stargazers) - SSH-based. Client is open source. Server doesn't appear to be.
* [SSH-J.com](https://bitbucket.org/ValdikSS/dropbear-sshj/) - Public SSH Jump & Port Forwarding server. No software, no registration, just an anonymous SSH server for forwarding. Users are encouraged to use it for SSH exposure only, to preserve end-to-end encryption. No public ports, only in-SSH connectivity. Run `ssh ssh-j.com` and it will display usage information.
* [Ngrok-operator](https://github.com/zufardhiyaulhaq/ngrok-operator) - Ngrok but integrated with Kubernetes, allows developers on private kubernetes to easily access their services via Ngrok.
* [ngrok 2.0](https://ngrok.com/) - Probably the gold standard and most popular. Closed source. Lots of features, including TLS and TCP tunnels. Doesn't require root to run client.
* [CloudFlare Tunnel](https://developers.cloudflare.com/cloudflare-one/connections/connect-apps/install-and-setup) - Excellent free option. Nicely integrates tunneling with the rest of Cloudflare's products, which include DNS and auto HTTPS. Client [source code](https://github.com/cloudflare/cloudflared) is Apache 2.0 licensed and written in Golang.
* [Tailscale](https://www.tailscale.com/) [](https://github.com/tailscale/tailscale/stargazers) - Built on WireGuard. Easy to use. Doesn't include an HTTPS proxy on the public side, but could be combined with nginx/Caddy/etc. Client [code](https://github.com/tailscale) available with a BSD3 license + separate patents file.
* [Loophole](https://loophole.cloud/) - Offers end-to-end TLS encryption with the client automatically getting certs from Let's Encrypt. QR codes for URL sharing. Client is open source. Can serve a local directory over WebDAV. MIT License. Written in Go.
* [Packetriot](https://packetriot.com) - Comprehensive alternative to ngrok. HTTP Inspector, Let's Encrypt integration, doesn't require root and Linux repos for apt, yum and dnf. Enterprise licenses and self-hosted option.
* [Hoppy](https://hoppy.network/) - WireGuard-based. Provides static IPv4 and IPv6 addresses for your machines, which is a simple and useful level of abstraction. Targeted towards self-hosters and people behind NATs.
* [gw.run](https://gw.run/) - Specifically focusing on securely exposing internal web apps to a group of people; not for publicly facing apps. Share access via email address then allow users to log in with common login providers like Google.
* [inlets](https://inlets.dev/) - Used to be [open source](https://github.com/inlets/inlets-archived); now focused on a polished commercial offering. Designed to work well with Kubernetes.
