Claude · answer→Codex · critique
See the plan before you send.
The plan strip turns your wording into steps. Click a step to change the agent or its job. You always have the final say.
BUILT FOR YOUR MAC. OPEN SOURCE.
Two minds.
One thread.
You, Claude Code, and Codex.
A conversation where the best idea wins.
Let one answer and the other challenge it. Give them different jobs. Keep the whole conversation in one place, with the CLI subscriptions you already have.
Apple Silicon & Intel · No API keys · No extra account
One question. A better answer.Relay ↗
THE PLAN1 · Claude answers→2 · Codex critiques
Ask a follow-up, or bring a new perspective…
＋ / Relay⌄
Two perspectives. Shared context. You in control.Illustrative conversation
Official CLIs. Your existing logins.
Threads stored on your Mac.
One app. Both perspectives.
01 / THE CONVERSATION
Different minds.
A shared train of thought.
You set the direction. They bring the perspectives. Choose how the conversation unfolds.
THE HANDOFF
You→Claudeanswers→Codexcritiques
An answer is a starting point.
One agent takes the first pass. The other reads it, challenges the assumptions, and adds what’s missing. Swap the roles whenever you like.
TRY SAYING
@chat respond and @claude critique itA preview of the workflow. Agents run in the installed app.
02 / YOUR DIRECTOR’S CHAIR
Orchestrate.
Don’t copy and paste.
Less shuffling between windows.
More room to think with both.
Claude Model⌄ Codex Effort⌄
Set the mind. Set the effort.
Choose the model and thinking effort for each agent from the composer. Different jobs can call for different settings.
/Your skills.
Both agents.
Both agents.
Bring your own context.
Use existing Claude and Codex skills, attach files, and save shared memory. Code, HTML previews, and Mermaid diagrams render inline.
03 / A LITTLE MORE FREEDOM
Same conversation.
Smaller screen.
Step away from the desk, keep the thread. Turn on Phone access on your Mac, scan the QR code, and add tandem to your iPhone Home Screen.
Set up your iPhoneYour Mac stays awake and connected.
Your iPhone is a window onto it.
04 / GET STARTED
A new app.
The logins you already have.
Install tandem on a Mac. Sign in to Claude Code and Codex once. Bring them together.
tandem for Mac
Apple Silicon & Intel · Latest release ↗
Not sure which Mac? Open Apple menu → About This Mac. “Chip” means Apple Silicon; “Processor: Intel” means Intel.
OR INSTALL FROM TERMINAL
curl -fsSL https://raw.githubusercontent.com/ankitkapooor/tandem/main/install.sh | bashDownloads the latest Mac app to Applications.
- 1
Give your agents a home.
Install Claude Code and Codex CLI, then sign in from Terminal. Both are needed for two-agent workflows; one is enough for Solo.
claude then /logincodex loginUses your existing subscriptions and their usage limits. No separate tandem account or API key.
- 2
Download. Drag. Open.
Open the DMG and drag tandem to Applications. The app is currently unsigned: right-click it and choose Open on the first launch, then confirm if macOS asks.
The Terminal installer handles installation too. No Node or npm needed for the Mac download.
- 3
Check the dots. Start a thread.
Open Settings and check that your installed agents show green status dots. Type a question, choose a mode, and review the plan before you send.
Updates are offered in the app. Your threads and notes stay in
~/.tandem.
Add tandem to your iPhone ＋
- In tandem on the Mac, open Settings and turn on Phone access.
- Scan the QR code with your iPhone and open the link in Safari.
- Tap Share → Add to Home Screen, then launch tandem from the new icon.
Keep the Mac awake and on the same Wi-Fi. For access away from home, use Tailscale. The QR link contains a secret token: anyone with it can use your connected agents while Phone access is on. Turn it off when you’re done.
05 / A CLEAR PICTURE
Your Mac is the home base.
⌂
Local files. Direct connections.
Threads, notes, and uploads live in ~/.tandem. Prompts go to Anthropic and OpenAI through their official CLIs. tandem adds no hosted server in between.
↗
Built in the open.
Read the source, see how plans are made, or run it yourself. The Mac app includes its runtime; source development requires Node 20+.
Explore the repository ↗Do I need both subscriptions?＋
Use at least one installed and signed-in CLI with access to its provider. Solo works with one agent. Relay, Parallel, and Debate need both. tandem uses those tools’ existing authentication and usage limits; it does not include a model subscription.
Is this page the app?＋
This is the download and setup page. The actual application runs on your Mac, and optional iPhone access connects to that Mac. There is no hosted chat app on this domain.
What should I know before installing?＋
The Mac app is currently unsigned. Replies appear when each agent’s step finishes, rather than streaming word by word. Codex may not see attached images in resumed conversations, though it receives their file paths. Windows and Linux are not packaged yet.
My agent says “not logged in” or “CLI not found.”＋
Install the missing CLI and sign in in Terminal: run claude and then /login, or run codex login. Restart tandem afterward. Login slash commands belong in the CLI, not in tandem’s conversation.
How do updates work?＋
tandem checks GitHub for updates when it opens and every six hours. When an update is available, you can choose Update now or Later. You can also select Check for Updates in the tandem menu. Threads and notes are kept.