Guests and message limits
How to try Phases without an account, what the guest message allowance is, and what signing in adds.
You want to see whether the agent understands your problem before you create an account. You can. Open the site and start typing — no sign-up form, no email confirmation, no trial request.
What happens when you arrive#
The browser signs you in anonymously as soon as the page loads. There is no button to press; the send control stays disabled for the moment it takes and then becomes active. That anonymous identity is what your guest allowance is counted against.
Type your question the same way a signed-in user would. If you want a starting point, the empty chat has a small Suggestions button that reveals four example prompts and drops the one you pick into the composer for you to edit before sending. Your first simulation walks one of them through end to end, and How the conversation works explains what the agent does with your sentence once you send it.
The allowance#
A guest gets 5 messages per 24 hours by default. Both numbers are read from
deployment configuration (GUEST_MESSAGE_LIMIT and GUEST_WINDOW_HOURS), so a
given installation can be set differently. The number you actually have is the
one the product shows you, not the one in this sentence.
Three details are worth knowing, because they are not what most trial limits do:
- The window is fixed, not rolling. It starts at your first message. The count resets to 1 the first time you send a message after the window has fully elapsed — not gradually, one message at a time.
- The slot is taken before the model does any work. A turn that errors, or that comes back empty, still costs a message. There is no refund path.
- The count follows your anonymous identity, not your network. Your IP is stored only as abuse telemetry and never participates in identity, so colleagues on the same office connection do not share one allowance.
Once you have spent at least one message, a small banner above the composer
reads 3 free messages remaining. Sign in for unlimited access. When the
allowance is gone, it is replaced by:
You've used all 5 free guest messages. Sign in to continue the conversation and save your history.
with Sign in and Sign up buttons, and the send control is disabled. If a
message reaches the server after the allowance is exhausted, the request is
refused and the page shows the message Guest message limit reached. Sign in to continue.
If the quota service itself cannot answer, the request is refused rather than waved through — the check fails closed, and no free allowance is granted by accident. Common problems covers what each of these messages means alongside the other refusals you may meet.
What a guest does not get#
The guest view is the conversation and nothing else. The header shows the logo, a Login link and the theme toggle. The controls that open the simulation panel, the materials workbench, the Simulation Runs browser and the chat-history sidebar are rendered only for a registered user, so a guest has no way to browse stored runs or open saved artifacts later. See Sessions, runs and artifacts for what those surfaces do once you have them.
A guest identity also cannot own a workspace — the workspace bootstrap call refuses anonymous users outright — and cannot connect an external agent over MCP, which rejects anonymous callers. See Workspaces and roles and Use Phases from an MCP client.
Signing in#
Sign-in offers email and password, and — where the deployment enables them — a Login with GitHub button and a Continue with Google button. The same page carries a Continue as guest link back to the chat if you are not ready.
Once you are signed in, the guest counter no longer applies to you at all: the allowance endpoint reports the full limit for any non-anonymous user without touching the quota store. You also get:
- persistent chat history in the left sidebar, with search on ⌘K
- a personal workspace created for you on first sign-in
- the Simulation Runs browser and the simulation panel's Results tab
- stored artifacts you can reopen, and shareable conversation links
- workspace materials, so a chemistry you build once is reusable — see Workspace materials
Nothing about the physics changes when you sign in. The solvers, the material resolution rules and the refusals described in Known limits are identical for a guest and for a signed-in engineer. What an account changes is whether the work survives the tab being closed.