Writing code on a phone, and seeing what it did
Code is the one kind of writing with a column width decided decades ago by hardware, and a terminal that cannot show eighty characters is a terminal that lies about what it is printing.
Eighty columns is not a convention anyone is attached to; it is the width that error messages, diffs, log lines and table output are all still formatted to. Below it, output wraps, and wrapped output is harder to read than output that scrolls — a wrapped stack trace stops looking like a stack trace. This makes a terminal the clearest fixed-size object on the whole site, more exacting than a page or a frame, because the threshold is a specific number and either you are above it or you are not.
The second thing code wants is two panes: the file and the thing it produced. An editor beside a terminal, a diff beside the branch it is on, a pull request beside the discussion about it. Every app here already has both halves and has been showing them one at a time.
The order runs from apps that are two things in one window to apps that are one. None of this is testing — what each entry says it does comes from its own listing.
- 1
Textastic Code Editor
Alexander Blach
Syntax highlighting across more than eighty languages, connections to SFTP, FTP, WebDAV and Dropbox, and a built-in SSH terminal for working on the server directly. An editor and a terminal in the same app is the two-pane case stated outright, and until now one of the two has had to be hidden.
- 2
Git client - Working Copy
Anders Borum
Clones repositories locally, then edits, commits and pushes, with other apps reaching the same files; the listing notes that committing offline matters on a device moving in and out of coverage. Reviewing a diff before committing it is reading two versions of one file, which is a side-by-side job that a single column turns into a memory test.
- 3
SSH Client - Secure ShellFish
Anders Borum
Fuses SSH sessions with remote file access, supports full-screen editing with vim or emacs, and lets filenames be dragged out of the terminal as real files. Full-screen editors draw their own interface in character cells, so they are the strictest consumers of width there are: the editor's layout is the terminal's size.
- 4
Termius - Modern SSH Client
Termius Corporation
SSH, SFTP, Mosh, Telnet, port forwarding and jump servers, with a virtual keyboard covering the special keys a shell needs. The keyboard is the giveaway — it exists because a phone has neither the keys nor the room, and only one of those two problems is solved by opening the screen.
- 5
Prompt 3
Panic, Inc.
A native terminal emulator across the developer's own platforms, with Mosh and Eternal Terminal for holding a session open across bad connections. A session worth keeping alive for hours is a session you will be reading a lot of output from, and output is where the eighty columns are spent.
- 6
Runestone Text Editor
Simon Stovring
A plain text editor with syntax highlighting, line numbers, search and replace and a page guide. The page guide is a vertical rule at a chosen column — an interface element whose entire job is to mark a width, on a device that has not been able to show it.
- 7
GitHub
GitHub
Reading and replying to issues and pull requests, triaging, reviewing and merging, framed by its listing as the work that does not need a full development environment. A review is a diff and a conversation about the diff, which is two panes that the phone has been alternating between.
The selection and the order are ours. Each entry is written from that app’s own App Store listing, linked beside it, and this page from Apple's iPhone Duo product page. Drafted with AI assistance and checked back against those sources before publishing; the disclosure page explains how. The iPhone Duo has been on sale since 23 October 2026 and nothing here has been seen running on one, so what each entry says about the fold is an argument rather than a test.