Claude Code, Codex and Antigravity, running side by side
Should I use Claude Code, Codex or Antigravity, and can I use all three?
What each agent CLI is good at, where they differ in practice, and what it takes to keep all three running at once on one machine.
Most comparisons of these three try to pick a winner. That is the wrong shape for the question, because the people asking it usually already pay for two of them.
They are more alike than the marketing suggests
All three are terminal agents. You describe what you want, they read your project, edit files, run commands, and report back. All three are signed in against a subscription rather than metered by an API key. All three keep one account per machine.
The differences that matter day to day are smaller and more practical than the benchmark charts imply.
How much they show you
Claude Code and Antigravity stream their work as it happens. You watch the reasoning and the edits arrive, so you can tell working from stuck without doing anything.
Codex is quiet while it works and shows you the result when it finishes. On a long task that is a genuinely different feeling. Nothing is wrong, but you have less to go on while you wait.
How they take a large job
Given something big, all three will decompose it. They differ in how much they check back in, how much they will change without asking, and how they behave when a step fails partway.
There is no ranking here that survives contact with your codebase. This is the axis to test on your own project rather than read about.
What they cost when you have all three
If you already pay for two or three, the marginal question is not which one to buy. It is what you get from having them at once, and by default the answer is almost nothing, because only one can be signed in per tool per machine and you can only watch one terminal at a time.
The real constraint is one account per machine
Every one of these tools stores its credential in one place under your user account. Sign in a second time and the first sign-in is replaced.
That is fine for one person with one plan. It is the binding constraint the moment you have a work account and a personal one, or a client's account you need kept away from everything else, or three plans and one afternoon.
The workarounds are a second macOS user, a container, or signing in and out. Each of them works. Each of them costs enough friction that most people quietly stop switching and leave capacity idle.
What having all three at once is actually worth
Once several accounts really do run at the same time, a few things become possible that are not possible one at a time.
- Different tools on different parts of one job. The split does not have to be by tool, but it can be, and you learn quickly which one you prefer for which kind of change.
- Capacity that survives a usage limit. When one account hits its window, the others keep going. Held work restarts itself when the window comes back.
- A comparison worth trusting. Same repository, same goal, same moment, three agents. That tells you more about which tool suits your codebase than any benchmark.
- Accounts kept genuinely apart. A client's account never sees your personal history or settings, because the sessions cannot reach each other.
The setup
Nuvoa runs these three as panes in one macOS window, each pane signed in as an account of its own. You can run one of each, or three accounts of the same tool, or any mix. Each pane gets its own branch and working copy, so they can all work on the same project without overwriting each other.
The sidebar shows what each account has left of its usage window. You give one goal to whichever pane you put in charge, it splits the work across the others, and the results come back on a single branch for you to read.
Some honest notes. Codex panes stay quiet while they work here too, because that is the tool's behaviour and not something an app can change. The pane doing the planning spends quota on its own account. And splitting a goal well is a judgement call that is usually right rather than guaranteed.