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Crab Fit

Free, open-source availability heat map for group events

FreeCalendarChecked Oct 9, 2026
Visit crab.fit

What is Crab Fit?

Crab Fit is a free tool by Ben Grant for finding a time that suits a group. Someone creates an event with possible dates and a time range and sends the link around; each person marks when they are free, and the results update live as a heat map of the group's availability. No account is needed. The code is open source under the GNU GPLv3 and can be self-hosted, and the project is supported by donations.

Crab Fit is free to use. See every plan

Good for

  • Friends, clubs and coworkers picking a time for a one-off event
  • Groups whose members should not have to create accounts
  • People who want to run their own scheduling poll server

Worth knowing

  • Events are deleted after 3 months of inactivity, so it does not keep a long-term record.
  • The mobile app is for Android only; no iPhone app is listed.
  • Extensions are offered for Firefox and for Safari on Mac. The project's code notes that the Chrome extension was removed.
  • It needs a connection: the app's own message says a Crab Fit does not work offline.

Key features

Events created in one form
Name the event or leave the name blank to have one generated, pick specific dates or days of the week, drag out a time range and choose a time zone. There is no sign-up step.
Live availability heat map
Responses appear live on a heat map where darker cells mean more people are free. Hovering or tapping a slot shows who is available, and names can be clicked to view people individually.
Google and Outlook calendar import
When entering availability you can sync with Google Calendar or Outlook Calendar, or reuse a recent event. Importing overwrites the availability you had already entered.
Time zone handling
Each event stores the time zone it was created in, and a respondent can switch to their detected local time zone. Hours outside the event are greyed out.
Name and optional password per event
Respondents enter a name for each event and can add a password to stop others changing their availability. The site says passwords are hashed.
Open source and self-hosting
The code is published under the GNU GPLv3, and the repository links to a guide for running your own instance.

Crab Fit pricing

Starts at
Free
Free plan
Free with no account. The privacy policy says the service is provided at no cost, and the site asks for donations so that it can stay free for everyone.
Free trial
None listed
Crab Fit$0The complete web tool, the Android app and the Firefox and Safari extensions. Donations are optional.

Read from crab.fit on Oct 9, 2026. Prices change, so confirm with Crab Fit before you buy.

Pricing in detail

Works with

Crab Fit alternatives

All Crab Fit alternatives comparedAll calendar and scheduling apps

Common questions

Is Crab Fit free?

Yes. Crab Fit is free to use. Free with no account. The privacy policy says the service is provided at no cost, and the site asks for donations so that it can stay free for everyone.

How much does Crab Fit cost?

Crab Fit lists one plan. Crab Fit: $0. Prices were read from crab.fit on Oct 9, 2026.

What platforms does Crab Fit work on?

Crab Fit is available on Web and Android. It also has a browser extension.

Does Crab Fit have an iPhone app?

No iPhone app was listed when its pages were read on Oct 9, 2026. Crab Fit is listed for Web and Android.

Does Crab Fit have a Windows app?

No Windows app was listed when its pages were read on Oct 9, 2026. Crab Fit is listed for Web and Android.

Is Crab Fit open source?

Yes. Crab Fit is open source, according to its own site. It can also be run on a server of your own.

What does Crab Fit integrate with?

Crab Fit's listing names Google Calendar and Outlook Calendar. A listing names up to eight integrations, so it may connect to more.

Who makes Crab Fit?

Crab Fit is made by Ben Grant.

What are the alternatives to Crab Fit?

The closest alternatives to Crab Fit in our directory are When2meet, LettuceMeet, Rallly, Timeful and WhenIsGood. Each one has a side-by-side comparison with Crab Fit.

Sources for this page

The prices, plans, platforms and features above were read from these pages on Oct 9, 2026.