How to SSH from an Android phone
Connecting to a server from an Android phone is not something most people plan for. Then the production server goes down at 11pm and your laptop is in another room.
There are two realistic options: an Android SSH app or a browser-based client. Both work. They have different trade-offs.
Option 1: Termux
Termux is a free terminal emulator that runs in Android without rooting the device. It includes a package manager, so you can install OpenSSH directly:
pkg install openssh
Then connect the same way you would from a Linux terminal:
ssh user@your-server
Key management works through files in Termux's storage. You can use ssh-keygen to generate a key pair inside Termux, or transfer an existing private key to the device and reference it with -i.
The typing experience on a touchscreen is rough for anything beyond short commands. Termux works well if you have a Bluetooth keyboard. It is less comfortable for extended sessions without one.
Termux is available on F-Droid. The Google Play version stopped receiving updates and is outdated; the F-Droid version is the one currently maintained.
Option 2: JuiceSSH
JuiceSSH is an SSH client built specifically for Android. It has a proper on-screen keyboard with SSH-specific keys (Ctrl, Escape, Tab, arrow keys), connection management with saved hosts, and supports both password and key authentication.
The free version is sufficient for most use. The paid version adds port forwarding and a few other features.
It is more comfortable to use on a small screen than Termux because the UI was designed for it. The trade-off is that you are trusting a third-party app with your server credentials and private keys.
Option 3: Browser-based SSH
If you have Chrome or Firefox on your Android device, SSHDock works in the mobile browser. The SSH connection runs in the browser tab. No app to install, no key files to manage separately. You paste your private key into the connection form and it is stored in the browser's local storage.
The terminal emulator in SSHDock is touch-friendly. It is not as comfortable as a native app with a purpose-built mobile keyboard, but for quick access without installing anything it is a reasonable option.
Which one to use
Termux is the most capable if you are comfortable with a command line and want a full Linux environment on your phone. JuiceSSH is better if you want a polished mobile SSH experience with saved connections. Browser-based SSH is the fastest path if you just need to connect once without installing anything.
For managing multiple servers regularly from a phone, a dedicated app with saved connection profiles (JuiceSSH or a similar client) will save you time. For occasional access from any device, the browser approach is hard to beat for convenience.
One thing all three have in common: typing on a phone screen is miserable for anything more complex than a handful of commands. If you find yourself doing real work this way, a Bluetooth keyboard makes a big difference.