ChatGPT Chat vs Work vs Codex
What each of ChatGPT's three modes is for, where you can use them, and a simple test for picking the right one.
The short version
- Chat
- You want an answer. Questions, ideas, short writing, learning.
- Work
- You want a finished file. Spreadsheets, decks, reports, research write-ups.
- Codex
- You want working software. Apps, tools, websites, bug fixes.
One question decides it: do I want an answer, a file, or something that runs?
Chat: the conversation
The ChatGPT you already know. It's fast and back-and-forth, and it's the default side of the switch in the desktop app. Use the thinking control when a question needs more care.
- Explaining a concept in plain words
- Brainstorming names, angles or hooks
- Rewriting a message so it lands better
- Quick decisions and everyday questions
Explain how a sinking fund works using a $1,200 yearly insurance bill as the example.
Work: the hand-off
Work replaced the old agent mode. You describe the outcome, and it plans the steps, uses your connected apps and files, keeps going in the background and comes back with something finished.
It does its best work with real material and a clear brief: what to produce, from what, for whom, and what done looks like.
- A spreadsheet built from messy exports, with totals and a chart
- A short slide deck that summarizes a report
- A one-page comparison of competitors from web research
From the attached bank exports, build a spreadsheet of last quarter's spending by category with monthly totals, then a 5-slide summary of where the money went and three ways to cut it.
Codex: the builder
Codex writes and runs code for you. Describe the tool or site in plain English; you don't need to know how to code. Open it from the ChatGPT/Codex switcher in the desktop app, or use Codex Cloud for tasks that run on OpenAI's servers.
- A simple website or landing page with a signup form
- A small tool that cleans up or converts files
- Finding and fixing why an existing project won't run
Build a one-page site for my newsletter with a headline, three benefits and an email signup form. Explain how to put it online.
Where you can use each
- Chat
- Every plan, on every device.
- Work
- Free and Go: limited, desktop only. Plus, Pro and Business: desktop, web and mobile.
- Codex
- Desktop app on every plan. Codex Cloud works across devices; local projects need your own computer.
Plans and limits change often. Check the plan page in your ChatGPT settings for what your account includes today.
Starting on desktop, finishing on your phone
New Work tasks can continue on other devices if sync is on before the task starts. Tasks started earlier stay where they began, and any step that needs files on your computer only runs while that computer is on and online.
Your first week
- Install the ChatGPT desktop app so all three modes are in one place.
- Keep using Chat for quick questions. Nothing changes there.
- Give Work one real task you'd normally spend an afternoon on, with the files attached.
- Describe one small tool you wish existed to Codex and let it build a first version.