a-Shell is the open-source on-device Unix shell for iOS. It runs locally on the device via the ios_system project, vim, grep, python, lua, git, basic Unix tooling, all sandboxed inside a single iOS app. It is free, it is well-loved, and it does something genuinely useful: a real shell environment in your pocket without a server. ShellDrop is the inverse: it does nothing locally, exists only to talk to a remote machine over SSH, and is tuned for managing AI coding agents in tmux on that remote machine.
The two apps don't really compete. They share a category and aim at orthogonal use cases. Still, the comparison comes up. Here it is.
| ShellDrop 5 | a-Shell | |
|---|---|---|
| Primary role | Remote SSH client for driving agents | Local, on-device terminal |
| Voice dictation | Built in. On-device Apple speech free, or your own Groq key. | Not a listed feature |
| Paste a screenshot into a remote session (uploads, path at the prompt) | Yes. Any image, multi-image; agent reads them on the server | N/A. Local terminal, no remote session; use scp yourself |
| Attach a file to a remote session (uploads, path at the prompt) | Yes. Files, photos or video; agent reads them on the server | N/A. Local terminal, no remote session; use scp yourself |
| Pricing model | Free. No account, no in-app purchases | Free, open-source (BSD) |
| Persistent, background-kept-alive remote sessions | Yes. Opt-in keep-alive plus auto-reconnect | No. Plain ssh, no mosh or Tmux bundled |
| Platforms | Native on iPhone and iPad, Vision Pro with version 5, macOS coming soon | iPhone, iPad, Mac, visionOS |
| Account required | No | No |
| Telemetry | None | None |
| SSH | First-class client, with manager and keys | Bundles ssh, scp, sftp, ssh-agent at the prompt |
| On-device languages (Python, C, LaTeX, WebAssembly) | No, it runs nothing locally | Yes. A real on-device dev environment |
| Public-key auth (SSH keys) | Yes. Ed25519 in-app and Secure Enclave P-256 | Yes. Standard ssh keys via bundled ssh-agent |
| Secure Enclave hardware keys | Yes. P-256 private key never leaves the Secure Enclave | No |
| Tmux single-finger scroll | Yes | No bundled Tmux |
| iPad layout (incl. 13" iPad Pro M4) | Universal app, full-canvas landscape, centred toolbar | Universal app, iPad supported |
| Custom command shortcut | One Tap toolbar button | Shell aliases |
| Open source | No | Yes (GitHub) |
Copy an image anywhere on the phone and paste it into the session. Your agent reads it on the server. Multi-image paste works too. The same toolbar has a paperclip button for files: pick one from Files, or a photo or video from the library, upload over SSH, and the path lands at the prompt. a-Shell is a local, on-device terminal, so there is no remote session to paste an image or attach a file into; moving anything to a server means running scp yourself. For anyone feeding screenshots to a coding agent all day, that is the gap between one paste and a five-step detour.
The clipboard works the other way too. Ask the agent to write something, tell it to copy the result, and it lands on the phone's clipboard ready to paste into another app. It is opt-in and takes about ten seconds to set up. Terminal text selection is now a dedicated mode: toggle it on, long-press a word, drag the handles, copy. And Nerd Fonts (FiraCode and JetBrains Mono) ship bundled, so the glyphs nvim and LazyVim rely on render the way they should.
ShellDrop is built around the SSH connection manager. Save hosts, keys, sync via iCloud CloudKit, hop between sessions in tabs, and keep a remote session alive in the background with auto-reconnect. a-Shell bundles ssh, scp, and sftp commands you can run from its prompt, so it can reach a remote host, but the connection is a plain one with no mosh or tmux bundled to keep it persistent. The workflow stays at the shell level rather than the app level.
Single-finger swipe through tmux scrollback without entering copy mode. The toolbar carries Esc, Ctrl-C, arrow keys, Shift-Tab, and a tmux detach button at all times. If most of your remote work is inside a tmux pane attached to a coding agent, that is the difference.
ShellDrop generates P-256 keys inside the iPhone Secure Enclave. Private key cannot be exported, even by the app. a-Shell uses standard software ssh-keygen.
Universal app, full landscape, hardware-keyboard friendly. Toolbar centres on the big canvas.
ShellDrop adds Voice Drop, a built-in mic on the keyboard toolbar. It transcribes on-device with Apple speech at no cost, or through your own Groq API key for whisper-large-v3-turbo, and drops the words at the cursor without sending Return. Dictating a long prompt to an agent is the kind of input a phone keyboard is worst at, and it is where ShellDrop puts the least friction.
Version 5 also added custom key bindings for the keyboard toolbar: create your own Tmux-aware keys in Settings, Ctrl plus a key with an optional follow-up, and arrange them like any stock key.
This is the whole point of a-Shell. You can write code, run Python or Lua scripts, edit files in vim, use git, all on the device, without an SSH session. If you want to learn Unix tooling, prototype quickly without a server, or have a usable shell when you're offline, a-Shell is built for that. ShellDrop has none of this.
a-Shell is open-source on GitHub. ShellDrop is closed-source.
a-Shell has done interesting work integrating Python, Lua, JS, and WebAssembly tooling into the on-device sandbox. There is a genuine little Unix world inside it.
a-Shell runs on Apple Silicon Macs via the iPad-on-Mac path. ShellDrop is native on iPhone and iPad, the Vision Pro app arrives with version 5, and a macOS app is coming soon.
Running both is the right answer for many people. a-Shell when you're offline or learning, ShellDrop when you're SSH-ing into your real machine.
Yes. Open-source and free on the App Store. ShellDrop is also free.
a-Shell is an on-device Unix shell that includes an ssh binary. ShellDrop is a dedicated SSH client app with a connection manager, key store, tmux scrollback, and One Tap.
Yes. a-Shell ships a sandboxed Python and many Unix tools. ShellDrop does nothing locally; it only connects out over SSH.
Yes. Ed25519, ECDSA P-256/P-384/P-521 paste-import, plus Secure Enclave-backed P-256 keys.
ShellDrop. The whole app is built around remote tmux sessions attached to coding agents. a-Shell can SSH but is not optimised for that workflow.
Yes. a-Shell bundles ssh, scp and sftp, so you can reach a remote host from its prompt. It is a local-first terminal, though, with no mosh or persistent, background-kept-alive sessions. ShellDrop is the remote-first tool, built for keeping a tmux agent session alive over SSH.
ShellDrop is on the App Store. Universal iPhone and iPad, iOS 17+. Free, no subscription.
