Prefilling Lunacal Booking Form

How It Works

Lunacal supports prefilling booking fields by passing values either:

via URL query parameters
via embed configuration (if you embed lunacal directly on your site)

A sample booking form with various fields prefilled

Step 1 — Find the Internal Label of a Field

Every booking question has an internal label (also called an identifier). This is the key you’ll use in query parameters or embed config. For custom questions you’ve added: Go to Event Settings → Booking Questions, open any question, and copy its Internal Label. For built-in system fields, the internal labels are fixed:

Field	Internal Label
Name (full name)	`name`
First Name	`firstName`
Last Name	`lastName`
Email	`email`
Phone (booking question)	`attendee-phone`
Location (Guest Phone)	`location`
Additional Guests	`guests`
Meeting Notes	`notes`
Meeting Title	`title`

2. Prefill via URL Parameters

Append fields as query parameters to your booking URL: https://lunacal.ai/your-username/your-event?key=value&key2=value2

A. Name

Full name (single field): ?name=Jane%20Smith First name + Last name (if your event uses split name fields): ?firstName=Jane&lastName=Smith

If both firstName and lastName are present, they are combined into a single full name automatically.

B. Email

?email=jane@example.com

C. Phone Number

There are two separate cases for phone, depending on how your event is set up: Case 1 — Phone as a booking question If you added a Phone Number question under Booking Questions, use attendee-phone: ?attendee-phone=%2B919999999999 The + in a country code must be URL-encoded as %2B. Case 2 — Phone as the meeting location (Guest Phone Number) If your event uses Guest Phone Number as the location type, pass a location JSON object: ?location={"value":"phone","optionValue":"%2B919999999999"}

In this case, %2B replaces + in the phone number inside the JSON value.

D. Short Text Question

Use the question’s internal label directly: ?your-internal-label=Your%20answer%20here Example — if the internal label is company-name: ?company-name=Acme%20Corp

E. Long Text / Paragraph Question

Same as short text — use the internal label: ?your-internal-label=This%20is%20a%20longer%20answer%20spanning%20multiple%20sentences.

Pass the exact option value (case-sensitive) that matches one of the dropdown choices: ?your-internal-label=Option%20One Example — if the internal label is meeting-type and the option is "Product Demo": ?meeting-type=Product%20Demo

G. Multiple Choice — Single Answer (Radio)

Same format as dropdown. Pass the exact label of the option you want pre-selected: ?your-internal-label=Option%20Label

H. Checkbox / Multi-Select Question

Pass multiple values for the same key to pre-check multiple options: ?your-internal-label=Option%20One&your-internal-label=Option%20Two Example — if the internal label is topics: ?topics=Design&topics=Engineering&topics=Marketing

Pass true or false: ?your-internal-label=true

J. Additional Guests (Multi-Email)

Pass multiple emails using guests (or the legacy alias guest): ?guests=alice@example.com&guests=bob@example.com

K. Notes / Meeting Title

?notes=Please%20bring%20the%20Q2%20report ?title=Strategy%20sync%20-%20Q3

URL Encoding Rules

Character	Encoded As
Space	`%20`
`+` (in phone)	`%2B`
`@`	`%40`
`"`	`%22`

3. Prefill in an Embedded Lunacal Calendar

When embedding Lunacal with the JavaScript snippet, you can pass prefill values directly in the config object — no query params needed. Use the question’s internal label as the key, and the prefill value as the value.

Inline Embed Example

Lunacal.ai["your-event-slug"]("inline", {
  elementOrSelector: "#your-event-slug",
  config: {
    layout: "",

    // System fields
    name: "Jane Smith",
    email: "jane@example.com",

    // Custom booking questions — use the internal label as key
    "company-name": "Acme Corp",
    "meeting-type": "Product Demo",
    "topics": ["Design", "Engineering"],   // multi-select: pass an array
    "consent": true,                        // boolean: pass true/false

    // Phone as a booking question
    "attendee-phone": "+919999999999",

    // Additional guests
    guests: ["alice@example.com", "bob@example.com"],
  },
  calLink: "your-username/your-event-slug",
});

Lunacal.ai["your-event-slug"]("floatingButton", {
  calLink: "your-username/your-event-slug",
  config: {
    name: "Jane Smith",
    email: "jane@example.com",
    "company-name": "Acme Corp",
  },
});

Quick Reference — All Field Types

Question Type	URL Parameter Format	Embed Config Format
Full Name	`?name=Jane%20Smith`	`name: "Jane Smith"`
First + Last Name	`?firstName=Jane&lastName=Smith`	`firstName: "Jane", lastName: "Smith"`
Email	`?email=jane@example.com`	`email: "jane@example.com"`
Phone (question)	`?attendee-phone=%2B919999999999`	`"attendee-phone": "+919999999999"`
Phone (location)	`?location={"value":"phone","optionValue":"%2B91…"}`	Not supported via config
Short Text	`?internal-label=value`	`"internal-label": "value"`
Long Text	`?internal-label=value`	`"internal-label": "value"`
Dropdown	`?internal-label=Option%20Name`	`"internal-label": "Option Name"`
Radio (single choice)	`?internal-label=Option%20Name`	`"internal-label": "Option Name"`
Checkbox / Multi-select	`?label=Opt1&label=Opt2`	`"internal-label": ["Opt1", "Opt2"]`
Consent Checkbox	`?internal-label=true`	`"internal-label": true`
Additional Guests	`?guests=a@x.com&guests=b@x.com`	`guests: ["a@x.com", "b@x.com"]`
Notes	`?notes=value`	`notes: "value"`
Meeting Title	`?title=value`	`title: "value"`

Common Issues

Q: My dropdown prefill isn’t working. Make sure the value you’re passing exactly matches the option label, including capitalization and spacing. Q: My phone number prefill shows up without the + sign. The + must be URL-encoded as %2B in query parameters. For embed config, pass the + directly as a string (e.g., "+919999999999"). Q: The name field isn’t being filled. Check whether your event uses a single Full Name field or split First Name / Last Name fields. Use ?name= for the combined field, or ?firstName=&lastName= for the split version. Q: Checkbox options aren’t being selected. For multi-select and checkbox fields, each option must be passed as a separate parameter with the same key: ?topics=Design&topics=Engineering. In embed config, pass an array.

4. Prefill via URL Parameters (Scheduling Page & Embedded Page)

You can pre-fill all the booking questions on the booking form by using their corresponding internal label that you can see in the booking question tab. For example, for the question shown in the screenshot below, the question would show up as “What’s the main goal of this meeting?” and its internal label is main-goal. So we would use main-goal as the query param name to prefill the field. Booking question internal label

🔗 Example URL

https://lunacal.ai/your-username/your-event?main-goal=Consultation

{yourFieldIdentifier}

Spaces must be URL-encoded (%20), and + in phone numbers must be URL-encoded as %2B.

5. Pre-filling Phone Number Fields

Phone numbers can be pre-filled in two different ways, depending on how the phone field is set up: 1. Phone as a booking question If you’ve added a Phone Number booking question, use the attendee-phone parameter:

attendee-phone=9999999999

2. Phone as the meeting location (Guest Phone Number) If your event uses Guest Phone Number as the location, pass a location object instead. The country code’s + must be URL-encoded as %2B:

location={"value":"phone","optionValue":"%2B919999999999"}

6. Pre-fill in an Embedded Lunacal Calendar

You can use the same query parameter method in the embed as well. Alternatively, if you prefer not to use query parameters, you can configure the values directly in the embed settings. You have to use the booking question identifier (internal label) as the key.

Inline Embed Example (JavaScript)

Lunacal.ai["your-event-slug"]("inline", {
  elementOrSelector: "#your-event-slug",
  config: {
    layout: "",
    // Add your booking questions here.
    // Use the question's internal label as the key,
    // and set the value to the prefill text you want to pass.
    name: "pre-fill-name",
    email: "pre-fill-email",
    "custom-question": "pre-fill-custom-question",
    check: "pre-fill-check",
  },
  calLink: "your-event-slug",
});

​How It Works

​A sample booking form with various fields prefilled

​Step 1 — Find the Internal Label of a Field

​2. Prefill via URL Parameters

​A. Name

​B. Email

​C. Phone Number

​D. Short Text Question

​E. Long Text / Paragraph Question

​F. Dropdown (Single Select) Question

​G. Multiple Choice — Single Answer (Radio)

​H. Checkbox / Multi-Select Question

​I. Consent Checkbox (Boolean)

​J. Additional Guests (Multi-Email)

​K. Notes / Meeting Title

​URL Encoding Rules

​3. Prefill in an Embedded Lunacal Calendar

​Inline Embed Example

​Popup / Float Embed Example

​Quick Reference — All Field Types

​Common Issues

​4. Prefill via URL Parameters (Scheduling Page & Embedded Page)

​5. Pre-filling Phone Number Fields

​6. Pre-fill in an Embedded Lunacal Calendar

​Inline Embed Example (JavaScript)