Pre-fill your booking form and pass customer data through to Koalendar

One way to make your scheduling experience a bit more convenient and show your link recipients you are willing to do some legwork is personalization. There are two methods for doing this in Koalendar.

Method 1: Create a personalized link

This method is the simplest way to pre-fill the booking form for you invitee. However, only the name and email are pre-fillable this way.

From your dashboard, click "Share" on one of your booking page then "Prefill" on the top right:

(Here we've pre-filled the name as "John" and email as "john@google.com")

Then copy your link and share it with your invitee.

After selecting a date and time on your scheduling page, instead of having the booking fields being empty, they will now automatically be filled with the values you've provided.

Method 2: Prefill data via the query string

If you want to prefill more fields than just your invitee's name and email, you can pass that information in the link query string.

For example:

https://koalendar.com/e/slug?name=John+Doe&email=john.doe@gmail.com

You can pass the following parameters in the query string to personalize the link. All values should be properly URL-encoded.

Property	Description
`email`	The scheduler's email address to prefill.
`name`	The scheduler's first and last name to prefill.
`phone`	The scheduler's phone number to prefill (when using Phone Call as meeting location, otherwise see below how to prefill custom questions). The number should be provided as a numeric string, beginning with the country code (without parentheses, spaces, or dashes). For example, to prefill with the number (800) 555-0100, set the query string to value `+18005550100` .
`month`	The month to show on the calendar view (e.g. `2025-12`).
`date`	The date to select (e.g. `2025-12-24`).
`slot`	The time slot to select, in 24h format (e.g. `19:30`).
`duration`	The meeting duration to select, in minutes (e.g. `15`).
`guests`	The additional guests emails, separated by comma (e.g. `guest1@gmail.com,guest2@gmail.com` .

How to prefill custom questions

You can also prefill answers to custom questions like this: question_code=answer+to+question.

After creating a custom question, click to edit it and find the shorthand code in the header:

Click to copy the code, here "SNNDZ", and add it to your link:

https://koalendar.com/e/slug?name=john+doe&SNNDZ=42+Koa+Avenue

If you want to pass data this way without displaying it to your invitee, select "Hidden" as answer type: