How to Use Janus for Claude Code

Janus changes the next session, not the one already running

Janus saves the two local parts that make Claude Code recognize an account: the OAuth credentials in the macOS Keychain and the matching Claude settings file. Think of it as a locked key cabinet. Selecting an account puts that account's key and settings back in the live slot, ready for the next process to pick up.

That last phrase matters. A Claude Code process reads its credentials at startup. Switching in Janus does not change a terminal or IDE session that is already open. Quit or stop that process, switch accounts, then start a fresh Claude Code session.

The software does not merge subscriptions, transfer allowance, or create extra usage. Each login keeps its own paid access and limits. Use the separate Claude Code pricing guide for current plan costs. Janus changes login friction, not the plan budget.

This walkthrough is source-verified against Janus v1.1.0. It is not a hands-on reliability benchmark: no claim here depends on a measured switch time or an unreported test on a two-account Mac.

Install Janus only after making the trust decision

Janus supports macOS 13 or later on both Apple silicon and Intel. The pinned v1.1.0 release contains a DMG, a ZIP and SHA256SUMS.txt. The published DMG and ZIP both match that manifest.

The installation limitation is not cosmetic. Janus is ad-hoc signed and not notarized. macOS will identify it as coming from an unverified developer, and the project's installation instructions tell you how to remove the quarantine flag. That bypass is a trust decision because the app handles Claude Code credentials. Review the repository, choose the exact tagged release, and verify the downloaded file before following the quarantine instructions.

On a Mac, download Janus-1.1.0.dmg and SHA256SUMS.txt into the same folder, then verify the manifest:

shasum -a 256 -c SHA256SUMS.txt

Open the DMG, drag Janus to Applications, then follow the release's launch instructions if you accept the risk. The project also documents a Homebrew cask with --no-quarantine; the same trust decision applies.

The reason Janus needs broad local access is also the reason to inspect it. The app is not sandboxed because it must reach Claude Code's Keychain item and settings file. It is MIT-licensed and unaffiliated with Anthropic, but an open license is not a security review.

Save two Claude Code accounts

The clean setup uses two accounts you control and records the active identity at every handoff.

1. Sign in to Claude Code with account A. If Claude Code itself is new to this Mac, complete the normal setup first. The broader Claude Code setup guide covers that starting point.
2. Open Janus and read the current email shown in its window or menu bar. Press Save current account.
3. In Claude Code, sign out of account A and sign in once with account B.
4. Return to Janus. Confirm the displayed email is account B, then press Save current account again.
5. Janus should now list both accounts. Choose account A or B from the window, or use the menu-bar switch action.
6. Stop the existing Claude Code process and start a new one. The old process keeps the credentials it loaded earlier.
7. Before opening a client repository, confirm the email in Janus and run /usage in the new Claude Code session. Match its five-hour and weekly position to the intended account.

Janus saves the displaced account before it restores the selected one. It also obtains the replacement session before touching the live session. The documented failure behavior is conservative: a missing saved session or refused Keychain operation should leave the Mac on the account that was already active.

The two-account verification checklist

Use a low-risk repository for the first switch, not active client work.

• Before switching, note the email Janus marks as signed in and record the visible five-hour and weekly usage state.
• Leave one Claude Code session running so you can test the startup boundary.
• Switch to the second account in Janus and confirm the menu-bar email changes.
• Start a separate, fresh Claude Code process and run /usage.
• Check that the fresh process aligns with the second account's figures in Janus.
• Return to the process that stayed open. It should still behave as the first account's session because it loaded those credentials at startup.
• Switch back, restart again, and repeat the identity and usage checks before trusting the flow with billable work.

The goal is not to prove that a button changed color. It is to prove that the account selected in Janus is the one used by the next process, while the existing process remains unchanged.

Know whether a usage reading is remembered or fetched

Janus can show a correct old reading, which is different from a current reading. Claude Code writes usage into its settings while an account is active. When you switch away, that saved value stops moving. Version 1.1.0 labels the source so you can tell a remembered reading from one fetched from Anthropic.

Pressing Refresh asks for current usage once per saved account. For a parked account, Janus can renew an expired access token first and stores the replacement credentials before it uses them. For the account currently signed in, Janus does not renew the token because a running Claude Code process may still be holding it. Claude Code keeps that live token fresh itself.

Reset countdowns now tick while the Janus window is open. When a limit window turns over, the old percentage is cleared and a fetch is triggered. Until a fresh reading arrives, Janus shows a dash rather than guessing. That distinction matters when you are deciding whether the intended work account has room for a long session.

There is one documentation inconsistency in the tagged v1.1.0 repository. The README, release notes and source code describe usage requests to Anthropic, but the tagged SECURITY.md still says the app makes no network requests. The code sends usage requests to api.anthropic.com and token-renewal requests to platform.claude.com. Treat the source and the newer release notes as the operative behavior until that security page is corrected.

Six workflows where the switch pays for itself

The best fit is not someone collecting spare accounts. It is an operator with a legitimate reason to keep two identities separate on one Mac.

Do not use account switching as a way to share credentials or evade a plan limit. The useful pattern is separation among accounts you are authorized to control.

Two products worth building around this gap

Best bet: an account-safe cross-platform launcher

Build a launcher that binds a repository to an approved Claude identity, shows that identity before startup, and opens a fresh Claude Code process only after the user confirms it. The paying user is a consultant, agency operator, or mixed personal-and-work developer who cares more about avoiding the wrong account than shaving another click.

The demand is small but unusually direct. In the United States, claude code multiple accounts records about 90 searches a month, a keyword difficulty of 0 and a $19.94 cost per click. Another 10 searches a month are specifically for claude code multiple accounts windows. Janus is macOS-only, so Windows and Linux are an obvious product gap.

The smallest sellable version needs an operating-system credential-vault adapter, a repository-to-account map, a clear active-account badge and a launch wrapper. It does not need a team dashboard at first. The catch is severe: authentication files and token flows belong to another product and can change, while mishandling them creates a security incident. That risk is also why a trustworthy launcher can earn money.

This is the strongest opportunity. The search volume is lower than general usage-limit demand, but the problem, buyer and missing platform are sharply defined.

A usage provenance and reset monitor

Build a local monitor that always labels each reading by account, source and fetch time, then alerts before a scheduled coding job runs into a reset boundary. A solo power user might buy the personal version; an engineering team might pay for a policy layer that never exports raw credentials.

claude code usage limits records about 1,000 US searches a month, with a $12.71 cost per click. claude code usage limits check adds another 10. The demand is larger than account switching because limit anxiety affects almost every paid user.

The MVP is a menu-bar view, explicit remembered and fetched states, reset timers and a pre-launch warning. The catch is upstream dependence. Janus v1.1.0 uses Claude's OAuth usage and renewal endpoints, and those interfaces can change. A durable product needs graceful failure, no invented numbers, and a fast maintenance loop.

The limits are part of the decision

Janus is useful only if you are comfortable letting an unaffiliated local app move authentication material. Its saved tokens live in the login Keychain under the Janus service. Its settings snapshots live under ~/Library/Application Support/Janus/ with owner-only permissions, but those snapshots can include project paths and history. The security note also says its /usr/bin/security call briefly exposes the credential payload as a hex process argument to the same macOS user and to root.

The app is macOS-only, not sandboxed, ad-hoc signed and not notarized. Each update may prompt for Keychain access again because its ad-hoc signature can change. Usage fetching introduces network behavior that the tagged security page has not yet caught up with. None of this proves the app is unsafe. It does mean that convenience is not enough reason to install it on a shared, unmanaged, or high-risk Mac.

Janus also has a developer-cache cleanup feature, but that is not required for account switching. Keep the first adoption narrow: verify the release, save two authorized accounts, test the startup boundary, and leave cache cleanup for a separate decision.

The Monday move

Pick two accounts you control, download the pinned v1.1.0 release and its checksum manifest, and test the checklist in a disposable repository. Record the active email and usage before and after the switch. Confirm that a newly started Claude Code process changes account while the process you left running does not. Only then make Janus part of the routine you use before client work.

If you want an account-safe launcher or usage workflow built for your team, I can help design and automate it.